John Wolff's Web Museum

Rebuilding the Facit Pinwheel Calculator - Models TK, NTK, and C1-13.


 

Contents

Reference pages

C1-13, mid-1960s.
Facit C1-13, mid 1960s.

Introduction

These notes give a detailed step-by-step procedure for a complete disassembly and rebuilding of the Facit 13-digit hand-cranked calculators, models TK (1936-54), NTK (1954-57), and C1-13 (1957-72). The earlier Model T (1932-36) is not included as I have never seen one here in Australia.

Readers should be aware that the model names refer primarily to the external styling, and are only loosely related to the internal mechanism. While all Facits are the basically the same, there were a great many mechanical changes and technical improvements made during the 40-year development of this 13-digit family. Some were coordinated with the model or styling changes, but many others were introduced gradually as the need or opportunity arose. The Mechanical Changes page shows some of the more important variations. Further changes may have been made in maintanance during the working life of the machine, or more recently by collectors or enthusiasts. It is difficult to predict exactly what will be found in any particular Facit when you remove its covers.

In the procedures following, individual steps or sometimes whole sections have been marked for particular versions. Steps not marked apply to all versions (or all that I have seen so far). Please read each step in full before you start to do it, and ensure that it is relevant to your machine. If a marked step does not seem to match, please check the corresponding step(s) for the other versions. Please be aware that your machine may not correspond exactly to any of the versions described. Be sure to take your own notes of any differences.

The notes are intended to be read in conjunction with the C1-13 Technical Description page, the Facit 13 Mechanical Changes page, and the more general information in the Notes on overhauling a mechanical calculator in the Technical section. The Technical Description explains the operation of the basic Facit mechanism and illustrates most of the major components and assemblies. The Mechanical Changes page shows some of the alternative constructions that you may encounter, while the Notes on Overhaul describe more general techniques for disassembly, cleaning, and rebuilding. Please study this material carefully before commencing your overhaul and refer back frequently as you proceed, especially for the illustrations.

Rebuilding a C1-13 requires patience, care, and attention to detail. It does not require any special tools, beyond an ability to deal with tapered pins (as described in the Notes on Overhaul). A machine in reasonable condition can be be completely disassembled in about 3-4 hours. A difficult machine might take a couple of days. Washing and initial cleaning will take about 4 hours. Detailed cleaning, checking, minor repairs, and preparation for re-assembly will take anywhere from 3 hours upwards, depending on the extent of the problems encountered. The final assembly of the machine from a set of fully-prepared parts can be completed in about 4 to 6 hours, but I often find that many of the parts were not as "fully prepared" as I had thought. Double all of these estimates if this is your first major rebuild.

The procedure following has been prepared and refined during the complete rebuilding of a significant number of Facit machines. It works well for me, and I hope it will provide a useful guide to anyone faced with a similar task. It comes with no guarantees, and no responsibility will be taken for any consequences arising from the use of these notes by others.

My thanks go to Mr David Hoskins of Sydney for his many helpful comments and observations while using an early draft of these notes to rebuild his C1-13. I would welcome any further comments, suggestions, or advice of significant variations via the enquiry form.


Disassembly

Please review the material in the Technical Description of the Facit mechanism and the Notes on overhauling a mechanical calculator before you begin. Be careful to record the dimensions of all coil springs (diameter, length, wire thickness) so that they can be returned to their original positions. It is recommended that you print a copy of these notes and tick off each step as it is completed. Proceed as follows:

  1. Covers - TK
  2. Remove the top and back covers, the three clearing levers, and the side covers (24 screws). Removal of the right-hand cover requires the handle to be turned so that the end of the handle stop can be removed (one screw through the centre). If the handle is stuck, the usual cause is that the two small intermediate gears at the right-hand rear (which drive the carry rotor) are stuck tight to their fixed pivot pin. Apply solvent to the gears, work them until the handle can be turned, then remove the handle stop and side cover.
  3. Temporarily replace the accumulator clearing lever on the left-hand side.
  4. Remove the fixed masking plates in front of the rotor and registers, but leave the sliding position indicator in place.
  5. Invert the machine. Remove the four large screws and lift off the retainer plate and the rubber mat.

  6. Covers - NTK and C1-13
  7. Remove the three clearing levers. Observe that there are two small spring clips resting on the bottoms of the left-hand and right-hand-rear clearing lever holes. Press inwards on the clips and lift off the cover. Use a wooden or plastic tool to press the clips, and be careful not to slip and scratch the paint.
  8. Collect the small rubber mouldings from the four corners of the base.
  9. Invert the machine. Remove the four screws in the round rubber bushings and lift off the base. Note the arrangement of the rubber mountings.
  10. Remove the small right-hand cover if the winding handle will turn, otherwise leave it until later.
  11. Temporarily replace the accumulator clearing lever on the left-hand side.
  12. Remove the slotted backing plate behind the keyboard, and the fixed masking plates in front of the rotor and registers. Leave the sliding position indicator in place.
  13. Disassemble the base and top cover and set aside for cleaning.

  14. Pinwheel rotor removal
  15. Unhook the large rotor positioning spring from the post at the left-hand rear corner of the base plate. Hold the loop of the spring firmly with pliers and release it gently.
  16. Note how the positioning carriage under the rotor is supported by a 7mm round shaft underneath and a flat bar across the front of the machine. Work the round shaft free and remove it to the left. The TK shaft is retained by the side covers; the NTK and C1-13 have a retainer (flat washer) and screw at the left-hand side.
  17. Remove the two screws holding the flat carriage support bar across the front of the machine. Ease the bar out and down to clear the dowel pins, unhook the wire link to the division setup key, and remove the bar. Unhook the two springs on the bar to assist in cleaning.
  18. Remove the tension spring from the lever assembly behind the right-shift key. On very early TKs, unhook the torsion spring around the lower pivot. Pull out the pivot pin and remove the levers. If the pin is stuck it can be pushed out from behind. Remove the small roller and circlip (if present) at the end of the upper arm.
  19. Disconnect the long positioning arm from the pin at the left-hand end of the carriage. The pin usually has a circlip groove, but the clip is often missing.
  20. Note the vertical rotor clearing arm at the front right-hand side. The arm has a guide plate and post at the top and a small return spring through the side plate. Remove the short pin securing outer end of the spring, remove the post and guide plate, then undo the shouldered pivot screw and remove the arm.
  21. Remove the screws in the rotor bearings at each side and carefully ease out the bearings. Note and recover any shims on the ends of the rotor shaft or stuck to the inside of the bearings.
  22. Lift the rotor and pull out the carriage. If the carriage is blocked by the latch lever on the front key guide (early TK and C1-13), lift the rotor and carriage together and move them to the left. Let the rotor shaft sit in the bearing housings.
  23. Remove the two screws from the bar which supports the sliding indicator plate above the rotor. Note the type of screw used: some models have special shouldered screws, some have countersunk screws, others have plain M3. Push the rotor shaft to the left to provide clearance, then pull the bar and indicator plate forward and lift out.
  24. Lift out the rotor from the left-hand end and set aside.

  25. Carry rotor removal
  26. Remove the screw and spring washer securing the bell.
  27. Remove the screws and ease out the carry rotor bearings. Remove the rotor from the left-hand end. Check for shims on the ends of the shaft or stuck to the inside of the bearings, and set aside.

  28. Register preliminaries
  29. Unhook all of the register detent springs. The spring tails are at the top rear of the machine, just behind the slotted cross-bar at the back of the registers. Push the spring tails forward and to the right to release them from the tabs on the detent levers. Note that early TKs have a left-handed detent lever and spring at the far right of the counter register.
  30. Check that all the register wheels can be turned by hand. The numeral wheels are often stuck together side-to-side, and can be separated by placing a screwdriver blade between them and gently twisting. The star wheels below are sometimes stuck tight to their shaft. Coat the star wheels with solvent and work them loose. The wheels don't have to be completely free, just movable. Avoid getting solvent on numeral wheels or setting rings. The painted numbers are easily damaged, especially if long affected by oil, and the calculator is useless without them.

  31. Accumulator register
  32. Free up the accumulator shaft, pinion, and clearing lever so that they are able to move.
  33. Accumulator lever hold-down tool Press the accumulator clearing lever fully down and secure it in this position. The NTK and C1-13 have a service hole at the front of the side plate to receive a simple hold-down tool (a short length of round rod with a 5mm pin in the end, as shown opposite).
  34. Remove 2 screws from the cam plate at the left-hand end of the accumulator shaft and lift off the plate. Early machines also have a small dowel pin.
  35. To remove the accumulator shaft, its keyway must be aligned with invisible slots in the housing and in the numeral wheels. The keyway itself is not visible in early machines, but it is always aligned with the pin which engages with the cam plate.
  36. Very early TK: Rotate the shaft so that the keyway (or pin) faces vertically upwards. Rotate the dials by hand to bring 2.5 to the normal position (ie, halfway between 2 and 3 in line with the hole in the central support).
  37. All others: Rotate the shaft so that the keyway is horizontal and facing to the rear. Rotate the dials by hand to bring the zeros to the normal position (aligned with the hole in the central support).
  38. Withdraw the shaft to the left and collect the dials. Adjust the shaft and dial positions as necessary to keep the slots aligned.
  39. TK and NTK: Remove the compression spring from the shaft. It is not necessary to remove the fixed gear or pin unless repairs are needed.
  40. C1-13: Carefully disassemble and record the gear, springs, and washers remaining on the shaft.
  41. Leave the clearing lever held down.

  42. Counter register - TK and NTK
  43. Free up the counter register shaft, pinion, and clearing sector so that they are able to move.
  44. Remove the rubber buffer attached to the underside of the top cross-bar, just behind the counter clearing sector. Most machines had a neoprene buffer, but some had polyurethane which has almost always disintegrated. Push the clearing sector fully to the rear.
  45. Remove the small retainer plate on the detent cross-bar above the counter carry levers. Lift the levers and place a support under them so that their lower ends are held clear of the register.
  46. Carefully remove the screw holding the bearing retainer plate at the right-hand end of the counter register shaft. Remove the plate, shaft bearing, and compression spring.
  47. If available, insert a long M3 screw or shaft extension tool (see below) into the threaded end of the register shaft to provide a handle.
  48. Rotate the shaft so that the keyway is horizontal and facing forward. Set the dials by hand to bring 3.5 to the home position (ie, halfway between 3 and 4). In some early TKs the keyway must be turned to the rear and the dials set to 0.
  49. Gently withdraw the shaft as far as possible, adjusting the shaft and dial positions as necessary. This will allow removal of the two leftmost dials. Angle the shaft forward to remove the remaining dials, then withdraw the shaft from the housing. It is not necessary to remove the fixed gear or pin unless repairs are needed. In some early machines it may be difficult or impossible to bring the shaft forward with the detent levers still in place. In this case, complete the next section "Register detent and carry levers", then finish removing the register.

  50. Counter register - C1-13
  51. Free up the counter register shaft, pinion, and clearing sector so that they are able to move.
  52. Remove the rubber buffer attached to the underside of the top cross-bar, just behind the counter clearing sector. Most machines had a neoprene buffer, but some had polyurethane which has almost always disintegrated. Push the clearing sector fully to the rear.
  53. Carefully remove the screw in the spring retainer plate at the right-hand side of the counter register. In some early machines the plate is keyed to a thick metal sleeve around the spring. In this case, remove the retainer plate but leave the spring in place. Otherwise, remove the plate, spring, and thin plastic or metal sleeve.
  54. Locate the steel cam plate set into the sub-frame where the counter shaft passes through. In some early machines the cam plate is keyed to and retained by the thick metal sleeve; in later machines it has a locating tab and a large U-shaped spring clip immediately to the left of the sub-frame. If present, hold the clip firmly with pliers and pull it straight out. Keep any solvent clear of the numeral wheels.
  55. Rotate the counter shaft so that the keyway is horizontal and facing forwards. Set the dials by hand to bring 3.5 to the home position (ie, halfway between 3 and 4). Withdraw the shaft a short distance, twisting slightly and adjusting the dial positions as necessary. Push the cam plate to the right until it is clear of the sub-frame, revealing an opening for the shaft. Lift the complete register assembly up and out through the cutout in the frame.
  56. Remove the dials, then carefully disassemble and record the clearing components remaining on the shaft.

  57. Register detent and carry levers
  58. Free up the carry lever detent pins (in the top rear cross-bar) so that the levers will move up and down. The captive pins are sometimes stuck tight in the detent bar. Note that there is no detent pin on the leftmost counter carry lever (except on early TKs).
  59. If not done already, remove the small retainer plate on the detent cross-bar above the counter carry levers. Lift the levers and place a support under them so that their lower ends are held clear of the slots in the star wheel shaft.
  60. Remove the screw holding the star wheel shaft retainer bracket to the lower front face of the cantilevered support between the two registers. From the rear, push the retainer forward and out. Early TKs have a special retainer screw and no bracket.
  61. Star wheel shaft extension tool If you have the facilities, take a moment to make a star wheel shaft extension tool by fitting a M3/0.5 screw onto a length of 5mm rod, as shown opposite. Allow a good 25mm of rod between the screw and the handle. Otherwise, obtain a long M3 screw, or borrow a shorter one from the top of the carry lever detent bar. Screw the extension into the left-hand end of the star wheel shaft. Tap the shaft to the right and work it free, then pull it out to the left. Rotate the shaft if the accumulator carry levers catch in the slots. Collect the 21 star wheels. In early TKs the rightmost star wheel has a very narrow hub on the right-hand side; otherwise the star wheels are all identical.
  62. Late TK and NTK: Remove the set screw for the carry lever shaft from the top edge of the left-hand side plate. The end of the screw may have been deformed by the drilling for the adjacent dowel pin.
  63. C1-13: Remove the screw, flat retainer washer, and small triangular locating plate (if preent) at the left-hand end of the detent and carry lever shafts.
  64. Free up the (larger) carry lever shaft, remove it towards the left, and collect the carry levers. The accumulator and counter levers are different and easily distinguished.
  65. Roll the machine onto its back. Remove the detent lever shaft, and collect the detent levers and springs. Early TKs have a left-handed detent lever and spring at right-hand end of the counter register; otherwise the parts are all identcal.
  66. From the top, remove 3 screws and lift off the upper carry lever guide.
  67. From the rear, locate the light horizontal spring along the back of the quotient coupling. Note carefully how this is attached at each end so that the spring lies flat along the coupling. In early TKs the spring can be removed easily; in later machines it is best to detach the slotted guide plate from the cantilevered support, remove the plate, and then unhook the spring. Check that the coupling is free to slide along the counter drive shaft.
  68. Remove the two screws at each end of the carry lever detent bar. Ease the bar off its dowels and remove, then remove the centre support. Do not remove the centre support first, as downward pressure on the screws may damage the unsupported die-cast cross-bar.
  69. Release the accumulator clearing lever.

  70. Right-hand side plate
  71. Remove two screws under the base. Ease the side plate up off its dowels and disengage it from the interlock shaft. Lift out the entire side plate assembly complete with counter drive shaft and quotient coupling plate.
  72. Remove the sliding quotient coupling and the counter drive pawl from the counter drive shaft.
  73. Remove the counter clearing handle, trim sleeve (if present), circlip (if present), and spring, then remove the clearing arm and sector. It may be necessary to assist the sector to clear the housing.
  74. Back off the 3 large sub-frame screws and tap them inwards to loosen the sub-frame, then remove the screws and slide the sub-frame and the large gear off the counter drive shaft. Remove the gear.
  75. Remove the small detent pin from the bushing at the bottom of the sub-frame. Early models have a leaf spring which can be lifted and carefully turned aside; later models have a coil spring and circlip.
  76. Note that the small indicator lever at the top of the sub-frame is permanently staked in place. On C1-13s, remove the spring and wire retainer to avoid loss during cleaning. The TK and NTK have a spring on the indicator flag instead of on the lever.
  77. Locate the pivot point of the V-shaped counter reversing reset lever. TK and NTK have two levers on a screw-in pivot which is staked to the sub-frame. Early C1-13s have one lever with a fixed pivot and circlip attached to the sub-frame; late C1-13s have a removable pivot attached to the side plate. Disassemble the levers and pivots according to the arrangement found.
  78. TK and NTK: Remove the small spring from the rotor interlock arm at the front of the sub-frame. Support the collar on the spring-loaded latching pin and drive out the rolled pin. Remove the compression spring, flat washer, and latch pin, then undo the shouldered screw and remove the interlock arm.
  79. The counter drive shaft is held by a captive detent ball inside the large bearing in the side plate. Pull out the shaft, gear, and spacer bracket together. Remove the outer gear from the bearing (if it doesn't fall out), and remove the screw-in locating pin for the spacer bracket. Early machines have a fixed pin.
  80. NTK and C1-13: If the winding handle was previously stuck, it should now be possible to turn the handle and remove the filler plate.
  81. Remove the counter drive shaft bearing. The early TK has the detent ball and spring in a cut-away at the top. Be careful that the spring does not fly out as the bearing is withdrawn. Later machines have the ball, spring, and a short retainer screw in a cut-away at the bottom. Remove two screws, withdraw the bearing, and recover the tiny coil spring and detent ball.
  82. Remove the rotor clearing handle, trim sleeve, spring, and the shaft and roller assembly.
  83. Remove the shouldered pivot screw and keyboard interlock lever at the bottom front of the side plate. TK and NTK also have a spring to a post above.
  84. Support the hub of the winding gear and drive out the tapered pin, usually towards the front. Remove the gear and withdraw the handle.
  85. Note the arrangement of the full-cycle pawl on the back of the driving gear, then extract the wire circlip and remove the pawl and spring.
  86. Disassemble the winding handle and spring-loaded pin. In early TKs the pin is retained by a screwed collar at the outer end of the handle; later models have a plain collar with a rolled pin. To remove the rolled pin, take a piece of thin card or shim about 15x30mm and cut a slot 4 wide and 10 deep in one end. Push the pin outwards until the collar is clear of the handle, then slip the card in behind to retain. Support the collar and drive out the pin.
  87. Remove the long handle bearing and the handle stop pillar (where possible) from the side plate. On late C1-13s, remove the eccentric adjusting cam set into the handle stop mounting plate.
  88. TK only: Remove the large screw securing the intermediate gear pivot post from the outside. Press out the post and remove the gears. Some versions of the pivot post have splines pressed into the side plate, so do not attempt to turn the screw head on the inside of the post.
  89. NTK and C1-13: Carefully extract the wire clip securing the two small intermediate gears to their fixed post. Keep a finger on the post so that the clip does not fly off when released. Remove the two gears.

  90. Left-hand side plate - TK and NTK
  91. Loosen the lock nut and remove the pivot for the rear interlock shaft. Early TKs have a plain bearing with a retainer washer and screw instead of an adjustable pivot.
  92. Remove two screws under the base and ease the side plate up off its dowels. Lift the rotor interlock arm clear of the keyboard mechanism and withdraw the side plate. Recover the 2mm thick spacer washer from the end of the front key shaft (not present on early TKs).
  93. Remove the rotor interlock arm with one screw and flat washer from the outside.
  94. Remove the triangular locating plate for the carry and detent shafts (inside top, not present on early TKs).
  95. Remove the accumulator clearing arm, guide plate, spring, and rubber buffer.
  96. It is best not to remove the rotor buffer pin or the adjustable stops.

  97. Left-hand side plate - C1-13
  98. Loosen the lock nut and remove the pivot for the rear interlock shaft.
  99. Remove two screws under the base and ease the side plate up off its dowels. Lift the rotor interlock plate clear of the front key guide and remove the side plate.
  100. Remove the circlip, guide screw, and rotor interlock plate.
  101. Remove the accumulator clearing arm, spring, and rubber buffer.
  102. It is best not to remove the rotor buffer pin or the adjustable stops.

  103. Base plate and keyboard
  104. Extract the rear interlock shaft towards the right. Lift the setting arm and turn the forked arm downwards to pass it under. The shaft can be removed easily with proper manipulation.
  105. TK and NTK: Remove the small spring from the riveted lever at the top of the detent plate at the right-hand end of the interlock shaft.
  106. C1-13: Remove the small lever and spring at the bottom of the detent plate at the right-hand end of the shaft.
  107. Note the arrangement of the small lever and torsion spring between the 3 and 4 keys. Unhook the spring from under the post on the lever.
  108. Unhook the torsion spring on the side of the left shift key. On early TKs, unhook the similar spring on the division shift key.
  109. Unhook the vertical spring near the centre rear of the rocking escapement plate. Leave the bottom end attached to the wire retainer under the baseplate.
  110. Back off the locking screw for the front key shaft on the top of the left-hand pillar. Note that this is usually a plain screw, not a grub screw. The end may be deformed from contact with the shaft, and undoing it further than necessary may damage the tapped thread in the pillar.
  111. TK and NTK: Remove the three locating pins in the front key shaft. TKs have plain or tapered pins which were inserted from the top. If the pins need to be driven out, rotate the shaft half a turn and support the underside through the cut-outs in the base. NTKs usually have rolled or serrated pins which can sometimes be pressed out with pliers. Be very careful not to bend or damage the shaft.
  112. TK and NTK: Withdraw the front key shaft to the left. Recover two thin flat washers from the right-hand end, one from the left of the escapement plate, and one torsion spring, washer, and light compression spring from the left-hand side. Early TKs have another torsion spring on the division shift key.
  113. C1-13: Remove the circlip from the right-hand end of the front key shaft. Tap the front key shaft slightly to the right to work it free, then withdraw it to the left. Be careful not to damage the circlip groove.
  114. Back off the locking screw above the rear key shaft about 2-3mm to clear a groove in the shaft. Work the shaft free and remove it to the left.
  115. TK and NTK: Remove the bridge over the shift keys at the left-hand side.
  116. Lift out the rocking escapement plate and remove the pawls (C1-13) and spring. The TK and NTK have riveted pawls; the C1-13 has replaceable pawls with circlips.
  117. Lift out the lever and spring between the 3 and 4 keys.
  118. Lift out the three shift keys, and remove the spring from the small lever on the left-shift key. Lift the number keys, disengage them from the setting arms, and lift them out.
  119. Unhook the spring from the curved setting interlock lever (between the setting arms) to the wire retainer under the base plate. Remove the lever, then remove the retainer and the larger spring. This setting interlock is not present in early TKs.
  120. Unhook the two springs from the setting arms and push the springs and retainers out through the baseplate. Early TKs have wider springs which must be disconnected separately.
  121. Back off the locking screws in the three rear pillars, push out the short pivot shafts, and remove the setting arms.
  122. TK only: Remove the key backrest from behind the three rear pillars.
  123. Remove the small spring behind the left-hand end of the front key guide plate, and another on the small latching lever (where present) near the right-hand end. The latching lever was used on some early TKs, then deleted, then reinstated on the C1-13.
  124. Remove two screws securing the sliding aperture plate(s) to the front key guide. The TK has shouldered screws; the NTK and C1-13 have plain screws and bushes. Very early TKs and the C1-13 have two aperture plates and a spring friction plate at the left-hand side. Note the arrangement, then remove the plates and bushes.
  125. Remove the front and centre key guides.
  126. Remove the large pivot screw at the left-hand rear, and the circlip on the roller arm assembly at the front right. Lift out the roller arm, connecting link, and carriage positioning arm and disassemble.

  127. Carry rotor disassembly
  128. Support the hub of the outer gear and drive out the tapered or rolled pin. Remove the gear and lift the counter carry rotor from the shaft. Recover any shims between the two rotor sections, at the ends of the rotor shaft, or stuck to the inside of the bearings.
  129. Wrap a rag around the carry rotor, hold firmly, and undo the nut with a 15mm ring spanner. Alternatively, grip the nut gently in a vice, hold the rag firmly with two hands, and unscrew. Remove the discs, noting numbers, shims, and the arrangement of the alignment rods (if present). Repeat for the accumulator section.

  130. Pinwheel rotor disassembly
  131. Support the hub of the left-hand flange and drive out the pin. Tapered pins were generally inserted from the rear; rolled pins can be driven out in either direction. Be very careful to keep the left-hand end upright and under firm control when the pin is out.
  132. Remove the return spring from the rotor clearing wedge.
  133. Remove the screw and spring washer securing the rotor cross-bar to the left-hand drive flange. Hold the shaft upright with the flange at the top. Remove the flange, hold the ball sleeve so that it stays on the shaft, then lift off the rotor and cross-bar and set aside. Immediately replace the end flange, or tie a retainer through the hole at the end of the shaft to keep the bearing together.
  134. Study the notes on reassembling the linear bearing in Appendix 1 and decide how to proceed. Provided that the shaft is in good order, the tabs at the right-hand end of the bearing sleeve are not broken, and the rubber buffer disc at the right-hand end is still flexible, the bearing can sometimes be washed out well enough in place. Otherwise, hold the bearing vertically over a dish, lift out the shaft, and collect the 1/8" balls. Remove the rubber disc from against the right-hand flange.
  135. Slide the rotor cross-bar over to the right. Pull the clearing wedge to the right and down, then remove both parts.
  136. Wrap a heavy rag around the rotor, hold firmly with both hands, and unscrew the nut with a 24mm ring or socket spanner. In the absence of a suitable tool (or a third hand), place the rotor nut in a vice and tighten just enough to hold. Any significant pressure will distort the inner sleeve and destroy the calculator. Hold the rag and rotor with both hands and unscrew. The nut will usually be very tight.
  137. Lift off the end plate and remove the setting rings, pins, and pinwheel discs one at a time. Use plenty of solvent (and patience) if the pinwheels are stuck to the central core, but keep solvent away from the painted numerals. Note the corresponding numbers on the discs and rings, and the order of assembly.
  138. Remove the right-hand end plate(s)from the core, and remove the key from the keyway.
  139. Do not attempt to remove the driving gears from the rotor shaft.

Cleaning

Please review the general information about cleaning and checking in the Notes on overhauling a mechanical calculator, and proceed as described.

Be particularly careful of painted numbers on the setting rings and numeral wheels. The calculator is useless without them. The white paint is easily destroyed by alcohol or ammonia-based cleaners, but is generally not affected by a short wash in kerosene or hydrocarbon de-greasers.

Initial washing of the disassembled parts will take about 3 hours.


Reassembly

Please review the material on Reassembly in the Notes on overhauling a mechanical calculator.

Moving parts should be lubricated sparingly as they are assembled. Apply a thin film of oil to steel parts with a (slightly) oily rag to prevent rust, and apply light oil to gears, pivots and bearings. The pinwheels and setting rings should not receive any further oil.

In the notes following, screws listed as (eg) M3x8 are 3mm diameter, standard pitch (0.5mm), and 8mm overall length. Tension springs listed as (eg) 3x10x0.3 are 3mm outside diameter, 10mm closed coil length, and 0.3mm wire diameter. Spring sizes were changed often, and springs were not always replaced correctly in previous repairs. Use your own discretion if your machine differs from the sizes shown below.

  1. Base plate and keyboard
  2. TK and NTK: Check the front key shaft carefully. The shaft can easily be bent during insertion and removal of the three small pins, and can be expanded sideways if the pins have been driven in too far. Repair any damage so that the whole of the shaft will pass easily through the three supporting pillars on the baseplate, and through the close-fitting pivot sleeve on the right-shift key.
  3. Fit the centre key guide into its locating holes with the vertical fingers toward the rear. Fasten with 2 screws M3x8. Check that the fingers are all in a straight line.
  4. Insert the larger wire spring retainer through the base and into the large hole in the bottom of the key guide. Attach the escapement plate return spring 6x6.5x0.5 with the open side of the top loop facing forward. Early TKs have a larger spring 9x6x0.6.
  5. Fit the front key guide into its locating holes and fasten with 2 (or sometimes 3) screws M3x8. Check that the fingers are all in a straight line and that the swinging interlock arms all move freely.
  6. Fit the setting arms, pivot pins, and screws M3x8. The straight setting arm mounts on the left, and above the offset arm. If the pivot pins have a reduced centre section, the longer end of the two outer pins should go to the inside.
  7. Fit the wire retainers to the two 4x9x0.25 springs, push them up through the baseplate, and attach them to the setting arms. Early TKs have larger springs which must be connected from above.
  8. If the keytops have become detached, replace them to agree with the numbers stamped on the keys. Insert the numeric keys, starting with 1 in the leftmost slot in the central guide plate. Keys 1 to 4 and 0 go on the left; 5 to 9 on the right. Early TKs will have a blank space in the central guide plate between the 0 and 5 keys; later machines will have an empty slot. The small hooks on the sides of the keys go behind the central guide plate with the hooked end upwards.
  9. Fit the spring to the pivoted arm on the left shift key. Early springs are 1.7x4x0.15; later are 3x4x0.25. Then place the three shift keys in position. In the C1-13, ensure that the short pivoted lever on the division shift key is pointing upwards.
  10. Place the curved setting interlock lever in position between the 0 and 5 keys, with its spring 3x5x0.3 into the small hole below. This lever is not present in early TKs. Check that the escapement spring in the larger hole is not caught under the keys.
  11. Place the short lever and torsion spring in position between the 3 and 4 keys. The pin on the side of the lever goes to the front and to the right. The longer end of the spring lies against the top of the lever and points forwards, while the short end points down at the rear. Ensure that the rear of the lever and the spring are above the central guide plate and are not caught under. Keep the lever in (approximate) position by mounting it on a short (50-70mm) rod or wire inserted through the front key shaft holes.
  12. Fit the pawls and 3x10x0.3 spring to the escapement plate and check that they move freely. The pawl with the chamfered end goes at the front. The long end of the of the thin lever across the top of the plate rests in front of the rear pawl.
  13. Check that the long end of the torsion spring (between 3 and 4) is still at the top and facing forwards, then set the escapement plate in position above the keys. The short end of the top lever sits in front of the pivoted vertical arm on or beside the division setup key.
  14. TK and NTK: Place the bridge in position over the shift keys at the left-hand side. The tab on the right of the bridge rests on the edge of the escapement plate.
  15. Insert the plain end of the rear (shorter) key shaft from the left, as far as the 3 key. Lift the right-hand end of the escapement plate and look in to ensure that the shaft passes behind the short tail of the torsion spring. Continue to feed the shaft through the curved interlock lever and the rest of the keys. In the C1-13, check that the right-hand end of the shaft passes through the broad fork in the pivoted arm on the division setup key.
  16. TK and NTK: Insert the long end of the front key shaft through the left arm of the bridge, then fit the small compression spring, flat washer, and the torsion spring for the left-shift key with its tail downwards. Continue to insert the shaft through the shift keys. Fit a flat washer between the bridge and the escapement plate, then continue through to the 9 key, pushing out the temporary wire. The wire can be removed when the 3-4 lever is properly mounted on the shaft. Fit the torsion spring for the division shift key (if present), then continue through the escapement plate.
  17. C1-13: Insert the shouldered end of the front key shaft from the left, pushing out the temporary wire. The wire can be removed when the 3-4 lever is properly mounted on the shaft. Engage the end of the shaft with the escapement plate.
  18. Check that all the hooks on the keys are still pointing upwards, and correct as necessary.
  19. Push down firmly on the forward end of the torsion spring between 3 and 4 and hook the spring under the pin on the lever. Operate the lever a few times to settle it, then check that the spring is not causing any stiffness in the 3 or 4 keys.
  20. When all seems well, check again that the key hooks are still pointing upwards, and that the cross-ways lever on the escapement is still positioned correctly. Check that the rear escapement pawl is pushed rearwards when the division setup key is pressed.
  21. TK and NTK: Check that the plain end of the left-shift key spring points downwards betwen the two key shafts, then hook the front end under the key.
  22. C1-13: Place the left-shift key spring over the front key shaft, with its plain end downwards between the two shafts. Hook the front end under the key.
  23. TK and NTK: Fit the three pins to the front key shaft. Keep the small spring and washer to the left of the leftmost pin, and the central flat washer between the escapement and the centre pin. Fit the remaining flat washers at the right-hand end to provide minimal free movement. The pins can usually be pressed in well enough with pliers. The centre pin is the most important, as it carries the impact forces from the escapement as the rotor steps to the left. Do not drive the pins without providing solid support directly below (through the cutouts provided in the baseplate). Be very careful not to bend or damage the shaft.
  24. TK and NTK: Tighten the locking screw in the front key shaft and check that the escapement plate rocks freely. Adjust the pins or shim washers to correct any stiffness. Release the locking screw when completed.
  25. C1-13: Fit the circlip to the right-hand end of the front key shaft.
  26. Position the rear key shaft so that it extends about 1mm to the right of the division setup key, then tighten the rear set screw in the left-hand pillar. Do not tighten the front screw.
  27. Attach the spring from the curved setting interlock lever (if present) to the wire retainer under the baseplate, then attach the larger spring to the tab or cross-bar on the escapement plate above. Check that the springs are clear of the keys and adjust as necessary.
  28. Fit the small roller and circlip (if present) to the right-shift lever assembly, then temporarily install the levers, pivot pin, and 4x24x0.4 spring near the left of the front key guide. Very early TKs also have a torsion spring on the pivot shaft.
  29. TK only: Fit the backrest bar under the rear of the keys with 2 screws M2x9 and spring washers.
  30. Hold down the front of the setting interlock lever (behind the 5 key) and check that all the numeral and shift keys operate smoothly.
  31. Early TK only: Fit the angle bracket for the rotor clearing arm to the front right-hand corner of the baseplate.
  32. Attach the slotted connecting link to the lower arm of the carriage spring assembly and pass it under the keys from the left. Fit the roller arm to its post at the right-hand front, and engage it with the slot in the link. Fit the circlip and the large pivot screw. Check that the mechanism swings freely. Do not attach the spring.
  33. Very early TK: Check that the sliding keyboard aperture plates are not bent or twisted. Stand the base upright and install the plates onto the front key guide with 2 shouldered screws. Fit the spring friction plate near the left-hand end of the inner plate.
  34. Most TK and NTK: Check that the sliding keyboard aperture plate is not bent or twisted. Stand the base upright and install the plate onto the front key guide. The TK has shouldered screws; the NTK has stepped bushes and screws M3x7. Longer screws may foul on the right-shift lever.
  35. C1-13: Check that the two sliding keyboard aperture plates are not bent or twisted. Stand the base upright and install the plates and spacer bushes onto the front key guide. Ensure that the wider ends of the plates are located under the fixed pin at the left of the key guide. Fasten with two screws M3x7. Longer screws may foul on the right-shift lever. In early machines the left-hand screw has a flat washer; the right has an asymmetrical bush with a thin wave washer under the outer plate to provide friction. Later machines have a spring-steel friction plate at the left and a flat washer at the right.
  36. Fit the spring to the small latching lever (if present) at the right of the front key guide, near the division setup key. Early TKs have 1.7x5x0.15 springs; C1-13s have 3x4x0.25.
  37. Late TK and NTK: Attach the 3x4x0.25 spring to the posts behind the left-hand end of the aperture plate. Lift the division setup key and check that the plate slides and returns freely.
  38. Early TK and C1-13: Attach the 3x4x0.25 spring to the posts behind the left-hand end of the rear aperture plate. Lift the division setup key and check that the rear (or only) plate slides, latches, and releases freely. Check that the front plate (C1-13 only) moves easily but stays where it is put.
  39. TK and NTK: Fit the 1.7x5x0.15 spring to the pivoted lever at the top of the right-hand detent plate on the rear interlock cross-shaft.
  40. C1-13: Fit the small lever, circlip, and 3x4x0.25 spring to the bottom front of the right-hand detent plate on the rear interlock cross-shaft. The pointed tail of the lever faces forward.
  41. Install the interlock shaft above the keys at the rear. Lift the right-hand setting arm and feed the shaft in from the right. Turn the offset arm downwards to pass it under the setting arms, then back upwards. The smaller interlock plate (if present) should face upwards between the two setting arms.

  42. Left-hand side plate
  43. Check that the spring-loaded buffer pin at the centre front is free to move. The spring is quite strong.
  44. Fit the accumulator clearing arm, handle, spring, rubber buffer, and sector guide plate (if present). The TK/NTK spring is 6x15x0.7; the C1-13 is 4.5x25x0.6. If the polyurethane buffer has disintegrated, a new one can be punched from 3mm neoprene sheet. The outside diameter is 12mm, with a 5mm hole offset by 2mm to provide an eccentric adjustment. Set the narrow side against the clearing arm and the broad side facing inwards to be clear of the bell.
  45. Late TK and NTK: Fit the triangular locating plate over the carry and detent shaft holes at the inside top of the side plate. The locating plate is not present in early TKs.
  46. TK and NTK: Fit the rotor interlock arm and fasten with 1 screw M3x6 and flat washer from the outside.
  47. C1-13: Fit the rotor interlock plate, front guide screw, and circlip.
  48. Early TK: Fit the flat washer retainer and screw M3x8 to the plain bearing for the rear interlock shaft.
  49. All others: Start the pivot screw for the rear interlock shaft. Early machines have a standard M6 thread; later have a fine M6x0.5.
  50. Early TK: Place the side plate in its (approximate) position on the base. Engage the rear interlock shaft with its plain bearing. Lift the rotor locking arm clear of the keyboard mechanism and slide the side plate into position. Engage it with the dowels and fasten with 2 screws M5x13 from underneath.
  51. Late TK and NTK: Insert a temporary wedge to hold the bridge over the shift keys fully to the right. Place the thick (2mm) spacer washer over the left-hand end of the front key shaft. Place the side plate in its (approximate) position on the base. Lift the rotor locking arm clear of the keyboard mechanism and slide the side plate into position. Engage it with the dowels and fasten with 2 screws M5x13 from underneath. Screw in the adjustable pivot to engage with the interlock shaft.
  52. C1-13: Place the side plate in its (approximate) position on the base. Lift the rear interlock shaft into line with its pivot and clear of the rotor locking plate. Engage the front of the locking plate with the leftmost slot in the front key guide. Ease the side plate down onto the dowel pins and fasten with 2 screws M5x13 from underneath. Screw in the adjustable pivot to engage with the interlock shaft.
  53. Push the front key shaft to the left until it contacts the stop pin in the left-hand side plate. This stop sets the position of the escapement, and hence controls the alignment of the rotor with the registers and the setting mechanism. Remove the temporary wedge (if fitted). Tighten the set screw, then back off slightly to allow adjustment later.

  54. Right-hand side plate
  55. TK only: Fit the larger intermediate gear to its pivot post, then the smaller gear in the same orientation. Align the splines (if present) on the post with those in the side plate, press in, and fasten with 1 screw M4x10 and spring washer from the outside. Check that the gears turn freely.
  56. NTK and C1-13: Fit the smaller intermediate gear to its fixed post, thin end down, then the larger gear. Check that the wire retainer ring is not loose or twisted and install. Check that the gears turn freely.
  57. TK and NTK: Fit the keyboard interlock lever and shouldered screw at the bottom front. The plain end faces forward, with the chamfered edge down. Attach the spring 4x8x0.4 to the post above.
  58. C1-13: Fit the keyboard interlock lever and shouldered screw at the bottom front. The forked end faces upwards and towards the rear at about 45°.
  59. Late C1-13: Fit the removable pivot for the counter reversing reset lever and fasten with the flat washer retainer and 1 screw M3x6.
  60. Attach the winding handle bearing and the handle stop post (if removed) with screws M3x8. On C1-13s, fit the eccentric adjuster and set it to the centre of its range.
  61. Assemble the winding handle, compression spring, stop pin, and retaining collar.
  62. Place the drive gear on the bench with the grooved side up. Place the large end of the full-cycle pawl spring in the groove. Note that the pawl is not symmetrical. Place it over the spring with the long pointed tooth facing downwards, and the side with the more evenly-spaced teeth on the left. Fit the retainer ring.
  63. Fit the winding handle and drive gear. Check that the tapers face in the same direction (usually towards the rear), then start the gear onto the shaft. Turn the full-cycle pawl so that the long tooth faces towards the centre of the rotor bearing. Insert the pin by hand and check that the pawl swings (approximately) equal distances up and down as the handle is turned. Support the hub of the gear and drive in the tapered pin.
  64. Fit the rotor clearing lever and roller assembly, and engage the pin with the interlock lever at the bottom front. Fit the trim sleeve and clearing handle on the outside. Attach the 5x47x0.5 spring from the clearing lever to the post at the rear of the side plate.
  65. Assemble the counter drive shaft bearing and fit it into its housing. In early TKs, place the 3/32" detent ball and spring into position and press the spring down as you ease the bearing into the housing. In later machines, assemble the ball, spring, and M3x4 retainer screw in the bottom of the bearing. Insert the bearing and fasten with 2 screws M3x8.
  66. Fit the pointed detent pin to the bushing at the bottom of the sub-frame plate. Early machines have a leaf spring; others have a compression spring and circlip.
  67. Rotor locking arm and latch TK and NTK: Fit the rotor locking arm and shouldered screw to the sub-frame. Fit the latching pin, flat washer, compresion spring, and retaining collar and press in the plain pin. The photo opposite shows the correct assembly (click to enlarge). Attach the spring 3x7x0.3 from the arm to the post below. This mechanism prevents incomplete rotor clearing operations. The arm is raised and latched as soon as the clearing handle starts to move, and is not released until the rotor returns fully home and presses on the latching pin.
  68. C1-13: Fit the 3x3.5x0.2 spring and wire retainer to the small indicator lever at the top of the sub-frame. Early machines have a spring on the indicator flag instead of on the operating lever.
  69. TK and NTK: Place the large counter drive gear in position on the sub-frame plate. Place the counter reversing reset lever in position below the gear with the V fork to the front. Place the offset L-lever on the same centre with the forked end downwards. Repair the staking damage to the thread on the pivot post, then screw in the post. Do not stake (or preferably Loctite) the thread until the resetting tests have been completed.
  70. Early C1-13: Place the large counter drive gear in position on the sub-frame plate. Fit the counter reversing reset lever to the fixed pivot pin on the sub-frame with the V fork to the front. Fit the circlip to retain.
  71. Late C1-13: Place the large counter drive gear in position on the sub-frame plate. Fit the counter reversing reset lever to its removable pivot on the side plate with the V fork to the front.
  72. Fit the screw-in retainer pin for the gear spacer bracket, immediately below the top sub-frame screw. Early TKs have a fixed pin.
  73. Locate the timing mark on the (smaller) outer gear. On early TKs it is a dot on the cam surface; on later machines it is a dot on the tip of one tooth (or two opposite teeth). Set the winding handle in its stop, align the timing mark with the dot or V on the side plate, engage with the driving and intermediate gears, and insert the hub of the gear into the counter drive shaft bearing. Check the timing marks again and correct as necessary.
  74. Note the two detent grooves in the short end of the counter drive shaft and the small centre dimple between. Start the short end of the shaft through the outer gear and into the bearing. Point the centre dimple towards the detent ball. Place the spacer bracket over the wedge gear and start it onto its locating pin. Align the wedge with the slot in the outer gear, then push the shaft in over the detents and fully home.
  75. Pass the long end of the drive shaft through the large gear and the sub-frame. Lift and hold the rotor clearing handle as you slide the sub-frame into position. Engage the rotor clearing shaft, keyboard interlock lever, high-heeled boot (TK/NTK only), removable pivot (late C1-13 only), and the three supporting pillars and push home. Ensure that the three sub-frame pillars are sitting flat and even against the side plate, then fasten with three large-headed screws M4x10. Operate the rotor clearing handle and check that the related levers operate correctly.
  76. TK and NTK: Check the starting pawl and spring at the top of the counter clearing sector and ensure that the pawl moves freely. Fit the clearing arm to the frame. Engage the pin with the fork at the rear of the reversing reset lever. Fit the circlip (if present) to the shaft, then attach the spring 5x31x0.5 to the post at the bottom rear. Fit the trim sleeve (if present) and clearing handle.
  77. C1-13: Fit the counter clearing arm and handle. Engage the pin with the fork at the rear of the reversing reset lever. Attach the spring 6x22x0.8 to the post at the bottom rear, then fit the clearing handle. In some machines there will be no tension on the spring until the rubber buffer holds the segment forward.
  78. Large gear timing marks Observe the timing mark (dot or line) on the hub of the large gear and align it with the corresponding mark on the sub-frame plate. Steel sub-frames have a dot; cast sub-frames have a small V. The photo opposite (click to enlarge) shows the timing marks in a C1-13. The TK/NTK gear has a plain hub and may have two (equivalent) timing marks.
  79. Check that the centre wedge gear can be pushed left and right to engage with the inner and outer gears. Push the shaft to the left, then carefully operate the counter clearing handle. Watch as the gear returns towards the centre position, and ensure that it engages with the centre detent. If the centre detent can not be clearly felt, rotate the shaft half a turn and try again. Repeat for the right. If either side fails to return fully it is likely that the reversing reset lever or its pivot is loose, or has been bent or twisted from forcing. Remove the lever and correct as necessary.
  80. Early TK: Attach the spring 4x6.6x0.4 to the small latch lever at the right-hand end of the quotient coupling. Check that the latch moves freely.
  81. All others: Assemble the small buffer pin, compression spring, and circlip on the right-hand end of the quotient coupling.
  82. Fit the counter drive pawl into the slot at the top right of the quotient coupling with the pawl tooth on the left. Align the internal tooth with the keyway and slide the coupling onto the shaft. With the wedge engaged with the outer gear and the handle in its stop, the pawl tooth must point down and slightly rearwards.
  83. TK and NTK: Place the completed assembly in (approximate) position on the base. Engage the bar behind the quotient coupling with the forked arm on the interlock shaft, then engage the end of the counter drive shaft with its plain bearing in the left-hand side plate. Lift the right-hand end of the interlock cross-shaft and engage the shorter pin on the detent plate with the plain bearing in the side plate. Ease the side plate down onto the dowel pins and fasten with 2 screws M5x13 through the base.
  84. TK and NTK: From the front, look down between the sub-frame and the side plate and locate the long pin at the bottom front of the detent plate. Lift the rotor clearing handle slightly for a better view. Observe the plain end of the offset L-lever against the side plate, near the back of the handle stop pillar. Lift the lever so that its lower forked end comes forward, and engage the fork with the pin.
  85. C1-13: Place the completed assembly in (approximate) position on the base. Engage the bar behind the quotient coupling with the forked arm on the interlock shaft, then engage the end of the counter drive shaft with its plain bearing in the left-hand side plate. Lift the right-hand end of the interlock cross-shaft and engage the long pin on the detent plate with the forked lever on the sub-frame. Engage the shorter pivot pin into the plain bearing below. Engage the keyboard interlock lever at the bottom front of the side plate with the slot at the end of the front key guide. When all is in position, ease the side plate down onto the dowel pins and fasten with 2 screws M5x13 through the base.
  86. Adjust the threaded pivot pin (if present) to provide a small amount of end play for the interlock shaft. Check that the detent plate is clear of the rightmost setting arm pivot pin, and adjust the pin if necessary. Check that the shaft moves easily between its three detent positions. Tighten the lock nut.
  87. Rotate the shaft so that the detent plate is in its lowest position. Release the small latch at the top right of the front key guide plate (if present), press the division setup key, and check that the detent plate rises to the centre position. Press the left shift key and check that the plate rises to the top position. Operate the rotor clearing handle and check that the plate returns to the lowest position.

  88. Register preliminaries
  89. Check that all the pins in the carry lever detent bar move freely. Note that there is no pin in the innermost slot on the counter side (except on early TKs).
  90. Attach the cantilevered support to the bar with 2 screws M3x16, then attach the bar to the sides with 4 screws M4x17.
  91. Insert the hold-down tool made during disassembly (or equivalent) to hold the accumulator clearing lever fully down.
  92. Repair any damage to the star wheel, carry lever, and detent lever shafts. Insert the shafts from the left and check that they pass easily through the three supports. The die-cast alloy sometimes creeps slightly with age, so it may be necessary to ease some of the bearing points. Remove the shafts when satisfactory, but leave the hold-down tool in place.
  93. Early TK: Insert the wire retainer into the recessed hole on the left-hand side, just below the counter drive shaft. From the rear, attach the quotient coupling spring 6x28x0.35 to the retainer and to the pin on the coupling. Position the lower carry lever guide plate over the coupling, then insert the star wheel shaft far enough to locate the two upper mountings. Fasten the guide plate to the centre support with 1 screw M3x12, spring washer and nut. Check that the coupling slides freely, then remove the star wheel shaft.
  94. All others: Quotient coupling spring From the rear, attach the small loop on the 6x12x0.3 quotient coupling spring to the right-hand end of the coupling. Attach the larger loop to the small hole in the lower carry lever guide plate. Position the plate over the quotient coupling, then insert the star wheel shaft far enough to locate the upper mountings. Ensure that the spring lies flat and even along the coupling and under the guide plate. The photo shows the correct installation (click to enlarge). Fasten the guide plate to the centre support with 1 screw M3x8 and spring washer. Check that the coupling slides freely, then remove the star wheel shaft. Note that the spring draws the coupling in the opposite direction in the early TK.
  95. Attach the slotted upper guide plate to the top front of the machine with 3 screws M3x6. If the plate has dowels or locating pins the screws should be tightened; if it has screw slots for lateral adjustment leave the screws loose.

  96. Accumulator register
  97. Examine the clearing teeth on the accumulator shaft and repair as necessary. If the end of the shaft has an internal thread, attach the extension tool to provide a handle.
  98. Ensure that the accumulator clearing lever is held fully down.
  99. TK and NTK: Place the compression spring 8.5x20x0.75 onto long end of the accumulator shaft.
  100. C1-13: Place the clearing gear onto long end of the accumulator shaft so that the notch engages with the broad pin near the end. Follow with the small spring and the small flanged washer, concave side first. Fit the washer over the spring, compress the spring, then fit the C clip into the groove. Place the plastic sleeve (if present) over the long end of the shaft, flanged end first. Follow with the large dished washer, concave side first, then the large spring.
  101. Very early TK only: Face the keyway vertically upwards and insert the shaft through the housing in the left-hand side. Place the numeral wheels onto the shaft with 2.5 facing forward. Adjust the position of the wheels as necessary. Engage the end of the shaft into the centre support, press in against the spring, and turn a wheel to retain the shaft.
  102. All others: Face the keyway horizontally to the rear and insert the shaft through the housing in the left-hand side. Place the numeral wheels onto the shaft with the zeros facing forward. Adjust the position of the wheels as necessary. Engage the end of the shaft into the centre support, press in against the spring, and turn a wheel to retain the shaft.
  103. TK and NTK: Temporarily fit the cam plate at the left-hand end and fasten with 2 screws M3x8 and dowel pin.
  104. C1-13: Fit the cam plate at the left-hand end and fasten with 2 screws M3x8.
  105. TK and NTK: Pull the top of the clearing gear forward until the shaft springs outwards into its home position. Remove the packing and allow the clearing lever to rise.
  106. C1-13: Insert a screwdriver into the end of the keyway and turn the shaft anti-clockwise until it springs outwards into its home position. From the front, reach in with a small hook and pull the bottom of the small clearing gear forward to set the end of the notch against the pin.
  107. C1-13: Turn the shaft anti-clockwise until the keyway points to the 12 o'clock position. Hold the clearing lever, remove the packing, and allow the lever to rise. Help the gears into engagement if necessary. The shaft will spring out into its home position as the lever begins to move, and the gear will spring back onto the pin at the end of the travel.
  108. Operate the clearing lever and check that the shaft makes a full turn on the forward stroke and remains stationary on the return. The operation may block until the detents are installed; in this case turn the dials and try again. In the C1-13, be careful that the gear and sector do not become disengaged at the end of the forward stroke. Sector travel will be limited by the rotor end flange when fully assembled.
  109. Adjust the rubber buffer so that there is just a little free movement at the end of the return stroke.

  110. Counter register - TK and NTK
  111. Push the counter clearing sector fully rearwards, so that it enters the slot in the carry lever detent bar.
  112. Examine the clearing teeth on the counter shaft and repair as necessary. Attach the shaft extension tool or long M3 screw to provide a handle.
  113. Face the keyway vertically upwards in very early TKs, or horizontally forwards in later models. Insert the shaft through the housing in the right-hand side. Place the numeral wheels onto the shaft, keeping the numbers in alignment. Engage the end of the shaft into the centre support and turn a wheel to retain.
  114. Remove the extension tool. Place the compression spring over the end of the shaft, then the outer bearing and its L-shaped retainer plate. Fasten with 1 screw M3x14.
  115. Operate the clearing lever and check that the shaft makes a full turn on the forward stroke, and remains stationary on the return.
  116. Fit the rubber buffer to the underside of the top crossbar and adjust so that there is just a little free movement at the end of the return stroke.

  117. Counter register - C1-13
  118. Push the counter clearing sector fully rearwards, so that it enters the slot in the carry lever detent bar.
  119. Examine the clearing teeth on the counter shaft and repair as necessary.
  120. Place the clearing gear onto short end of the counter shaft so that the notch engages with the broad pin. Follow with the small spring and the small flanged washer, concave side first. Fit the washer over the spring, compress the spring, then fit the C clip into the groove.
  121. Place the steel cam plate onto the long end of the shaft, dished side first. In very early C1-13s the cam plate is keyed to a thick sleeve which covers the gear and is then keyed to the retainer plate. Assemble this version so that the home position on the cam is towards the front, and the longer slot in the sleeve faces the clearing sector. Later machines have a separate cam plate with a locating tab.
  122. Assemble the numeral wheels onto the shaft, leaving about 3mm clearance from the cam plate. Keep the keyway and the 3-4 figures to the front.
  123. Place the assembly in position, with the cam plate on the right of the sub-frame and the tab (if present) facing forward. Ease the cam plate into its housing, then engage the shaft into the centre bearing.
  124. Check that the keyway is facing forward, the shaft is fully to the left, and the notch in the gear is engaged with the pin.
  125. Place the plastic sleeve (if present) over the short end of the shaft, flanged end first. Follow with the large dished washer, concave side first, then the large spring.
  126. Fit the retainer plate at the right-hand end, press in against the spring, and start the M3x8 screw. Temporarily insert the 5.5mm carry lever shaft from the right to locate the top of the retainer, centre the lower hole over the register shaft, and tighten the screw. Remove the temporary shaft.
  127. Draw the top of the small gear forward to take up the slack in the notch. Bring the clearing sector forward and engage it with the gear. Fit the rubber buffer to the underside of the cross-bar with the narrow side forward.
  128. Operate the clearing lever and check that the shaft makes a full turn on the forward stroke.
  129. Adjust the rubber buffer so that there is just a little free movement after the gear clicks back onto the pin at the end of the return stroke.
  130. Fit the retainer clip (if present) onto the inner face of the cam plate.

  131. Register detent and carry levers
  132. Early TK only: Locate the left-handed detent lever and spring, and the star wheel with the two short hubs, and set them aside for the last place in the counter register.
  133. TK and NTK: Temporarily remove the accumulator cam plate to provide access for the carry and detent lever shafts.
  134. Attach the extension tool (or long M3 screw) to the end of the star wheel shaft.
  135. Press the accumulator clearing handle down and start the star wheel shaft into the hole under the register shaft. Insert a 5mm pin into the service hole (if present) to hold the handle in position, or let the clearing sector return and rest against the star wheel shaft.
  136. Turn the machine upside down with the back towards you and support it at a suitable angle. For the remainder of this section only, left/right and up/down directions will refer to the machine as you now see it.
  137. From the left, start the plain ends of the detent and carry lever shafts into their holes below the accumulator. Leave the ends flush with the inside of the side plate.
  138. Take the carry lever with the bell hammer attached. Place the tail under the first slot in the detent cross-bar and engage the body of the lever with the first slot in the two guide plates. Push the lower shaft inwards through the hole in the bottom of the lever. Depress the pin in the detent bar and ease the tail up and over, then back slightly so that the star wheel shaft can be pushed into the upper hole. Leave the star wheel shaft flush with the lever, and the lower shaft just short of the next slot in the guide plate.
  139. Roll a star wheel into position on the first numeral wheel, with the longer hub to your right. Push the star wheel shaft inwards until flush with the end.
  140. Place a detent lever into the next slot, with the two teeth against the gear on the dial and the spring hook at the upper right. Push in the detent shaft and leave flush.
  141. Fit the next carry lever in the same manner as the first.
  142. Take a detent lever spring, hold the long end upwards and the short end towards you, and place it between the first detent lever and the second carry lever. Push the detent lever shaft inwards so that it passes through the coil of the spring. The short end of the spring must sit above the carry lever shaft.
  143. Proceed in similar manner to the end of the accumulator. Rotate the star wheel shaft if the carry levers catch in the slots. The process becomes more difficult as spring pressure on the shafts increases. Finish the accumulator side with a star wheel and spring, but engage the bottom shaft with the centre bearing before fitting the spring.
  144. Check that all the detent lever springs are properly located on the shaft, with their long vertical ends free and their short tails above the carry lever shaft.
  145. Feed the star wheel shaft through into the space above the counter register. Fit the remaining star wheels onto the shaft, long hubs to the right, so that they engage with the gears on the dials.
  146. Push the star wheel shaft into the right-hand bearing. Adjust its position so that there is a slot immediately to the left of every star wheel, and a slot for the retainer plate (if present) at the right of the centre support. Rotate the shaft so that the slots face towards the carry lever shaft.
  147. Continue to install the carry levers, detent levers, and springs in sequence across the counter register. Engage the bottom shaft with its bearing before finishing with the last spring. In early TKs, fit the left-handed detent lever and spring in the last position. Engage the upper shafts in the right-hand bearings.
  148. Stand the machine upright and remove the blocking pin from the accumulator clearing handle.
  149. From the front, position the star wheel shaft retainer around the central support and engage its longer right-hand end into the slot in the star wheel shaft. Fasten with 1 screw M3x6, then remove the extension tool. Early machines have a special screw and no bracket.
  150. NTK only: Fit the carry lever shaft retainer screw into the top edge of the left-hand side plate.
  151. TK and NTK: Re-fit the cam plate at the end of the accumulator register. This also acts as the retainer for the detent lever shaft.
  152. C1-13: Push the detent and carry shafts nearly home. Fit the triangular plate (if present), flat washer retainer, and M3x8 screw at the left-hand side.
  153. If the upper guide plate has been left loose, push it side to side and let it find its centre. Tighten the three screws.
  154. Fit the small retainer plate above the counter register carry levers and fasten with 2 screws M3x6. The lip faces downwards onto the levers. Press and reset all the carry levers, and verify that they click easily over their detents.
  155. Test all the dials by hand and verify that they turn easily and the detent levers rock freely.
  156. Facit detent spring tool Make a detent lever spring tool from a suitable piece of 1/16" (1.5mm) steel or brass rod. Use a jeweller's saw or a fine cut-off wheel in a Dremel tool to cut a deep V-groove across the end, as shown opposite.
  157. Invert the machine again and attach the detent lever springs. Place the V of the tool over the tail of the spring and press down. At the same time, press down on the register end of the detent lever to raise the spring anchor tab, then hook the spring under.
  158. Turn all the dials by hand and verify that they click over the detents. Avoid touching the painted numerals.
  159. Operate the register clearing handles and verify that the dials return to zero.

  160. Pinwheel rotor assembly
  161. Examine the pinwheels and ensure that the 5-pin arm and the zero latch move freely, and that the latch spring is properly attached. Check the guard plates and springs on the early TK rotor discs.
  162. Examine the setting rings and remove any burrs on the dished side caused by the action of the clearing wedge. The burrs will sometimes carve a matching groove in the underside of the next pinwheel and lead to a stiff setting action.
  163. Fit the key to the central core and ensure that it is held firmly in the flange at the end. Stand the core upright on its end.
  164. Fit the right-hand end plate(s), recessed side down. Early machines have a pressed steel plate followed by a flat plate; later models have a single die-cast plate.
  165. Place the #1 pinwheel onto the core with the pin slots upwards. Place four pins into the slots, leaving the ends slightly outside the edge of the pinwheel. Place the #1 setting ring in position with the flat side down. Engage the pins and 5-pin arm with the setting slot, then engage the zero latch.
  166. Repeat for pinwheels 2,3,4,5,5,4,3,2. Note that disc #1 and the first #5 have guide pins in the cut-away section to assist the clearing wedge. Some machines have guide pins on both #5 discs.
  167. Fit the end plate with the cut-away section facing towards the setting arms. Fit the nut with the hexagon side down. Tap the assembly on the bench to settle the discs, and tighten with fingers only.
  168. Verify that all the pinwheels operate freely. Use any suitable tool to simulate the operation of the setting arms. Press inwards to release the zero latch and turn the setting ring fully in each direction. There are no detents, so the rings should move perfectly freely. Correct any stiffness or stickyness, then tighten fully and check again.
  169. When all is working smoothly, place the rotor cross-bar in position from the left and insert the clearing wedge from the opposite side.
  170. If the rotor linear bearing has been disassembled, refer to Appendix 1 for instructions on reassembling the balls, sleeve, and shaft. Return here and continue.
  171. Place the rotor onto the bearing and fit the left-hand flange into position. Engage the cross-bar with the slot in the right-hand flange, and attach it to the left with 1 screw M3x7 and spring washer.
  172. Align the pin holes, support the hub of the flange, and drive in the tapered pin from the rear. Some versions have rolled pins.
  173. Attach the return spring 4x30x0.4 to the clearing wedge and check that it moves freely. The attachment at the right-hand end (wire retainer and/or holes) keeps the spring parallel to the clearing bar and inside the circumference of the end disc.

  174. Pinwheel rotor installation
  175. Check the fit of the two rotor bearings into their mountings. Ease any scrapes or nicks around the bearing or the housings in the side plates. The thinner (6mm) bearing goes on the left-hand side, the 7mm on the right. Remove the bearings.
  176. Temporarily remove the right-shift lever arm, spring, and pivot at the left of the keyboard.
  177. Set the winding handle in its stop. If the stop is fitted with the eccentric adjusting cam, set it to the centre of its travel. Check that the timing mark on the outer gear on the counter drive shaft is still aligned with the corresponding mark on the side plate.
  178. Align the timing mark on the large gear with the corresponding mark on the sub-frame plate.
  179. Check that the counter drive shaft can be pushed side-to-side through its detents, so as to engage the centre gear with either the large or small driving gears. Leave the shaft engaged with the outer gear.
  180. Hold the rotor with the cross-bar just forward of top. Insert the right-hand end of the shaft into the bearing housing, then lower the left-hand end into position. Engage the gears and start the two bearings into their housings.
  181. Check the rotor home position by lifting the interlock arm on the inside of the left-hand side plate. The arm should engage fully with the notch in the rotor end flange. If not, withdraw the right-hand bearing, disengage the gears, and turn the rotor to correct.
  182. Check that the timing mark on the large gear is still aligned with the mark on the sub-frame. If not, remove the right-hand rotor bearing, disengage the gears, and turn the large gear to correct. Repeat until the rotor position and gear timing are both correct. Push the rotor bearings home.
  183. Set the counter drive shaft to the centre position. Hold the rotor fully to the right to avoid fouling on the registers, and give the winding handle one turn clockwise. Note that the centre gear moves outwards. Carefully operate the counter clearing lever and check that the gear returns to the centre detent. If there is any resistance, stop immediately and repeat the alignment procedure. Repeat the test for anti-clockwise turns.
  184. When properly set, the machine will be able to turn clockwise, clear, anti-clockwise, clear, then clockwise again without any trace of sticking or jamming. Conversely, if the mechanism does stick or jam, it is not assembled correctly. Go through the alignment procedure again, and do not proceed until this test can be completed with no sign of trouble. Adjustment of the handle stop position (late C1-13 only) is rarely needed.
  185. Align the rotor bearing mounting holes and fasten with 3 screws M3x8. C1-13s have an adjustable cover plate at the left-hand end and 3 screws M3x9. Adjust the end stop (or shims at the right-hand end) so that the rotor shaft has a small amount of end play.
  186. Place the offset vertical arm which operates the rotor clearing wedge into position at the front right-hand corner of the base plate, and fasten with the shouldered screw. Draw the 3.5x4x0.4 spring through the adjacent hole in the side plate and insert the straight wire retainer into the recess.
  187. Fit the vertical arm support bracket to the frame with the slotted end down. Fasten with 1 screw M3x9 next to the rotor bearing (early TKs have 2 screws M3x10), and 1 screw M3x16 through the upper hole and into the round post. Check that the arm moves and returns freely.
  188. Attach the 3x10x0.3 spring to the locking pawl on the vertical arm of the rotor carriage.
  189. Operate the rotor clearing lever (or push the quotient coupling rearwards) to reset the interlock shaft to its first position.
  190. Push the rotor carriage positioning arm fully to the left. Place the rotor near the centre of its travel, and offer up the carriage with its vertical arm aligned with the groove in the rotor right-hand end plate. Lift the front of the locking pawl, then swing the carriage down and back into position. When properly engaged with the keyboard escapement, the front of the carriage should sit evenly about 6mm behind the front key guide.
  191. Attach the positioning arm to the pin and link at the left of the carriage. Obtain a replacement if the circlip is missing.
  192. Insert the plain end of the 7mm carriage support shaft from the left. Pass it through the carriage bearings and into the right-hand side plate. The TK shaft is retained by the side covers and may fall out until assembly is completed. In later machines, secure the shaft with a flat washer retainer and 1 screw M3x6 at the left-hand side.
  193. Refit the right-shift lever, pivot, spring, and torsion spring (early TK only) at the front left-hand side.
  194. Observe the locating pins at each end of the flat front cross-bar. Some machines have separate dowel pins, some have pressed dimples. Knock back the dowel pins (if present) to leave about 1mm on the inside face.
  195. Attach the 4x8x0.4 spring vertically between the front cross-bar and the long riveted arm behind, and attach the 3x10x0.4 spring between the arm and the small latch lever.
  196. Connect the double-ended wire hook between the division setup key and the the bottom of the vertical arm extending below the front cross-bar. Several combinations of attachment holes and posts may be found. In some machines the wire just hooks under the key, usually in front of the guide plate. Lift the cross-bar up to engage with the arm on the carriage, check that it is clear of the spring buffer at the left, align the dowels, and fasten with 2 screws M3x8.
  197. Hold the division setup key down and push the rotor fully to the left. Attach the large carriage spring to the post at the left rear corner of the baseplate.
  198. Operate the rotor clearing lever and check that the rotor returns correctly. Operate the left and right shift keys and check that the rotor steps correctly in both directions. Press and hold the division setup key, and check that the rotor runs fully to the left and is caught and held by the latch under the front cross-bar until the key is released.
  199. Check that the locking lever on the carriage vertical arm aligns with the slots in the underside of the front cross-bar. If these are reasonably well aligned, step the rotor a few places to the left and turn the handle slowly to check the alignment of the pinwheel pins and the register star wheels. Check that the setting arms move freely between the pinwheels without fouling on the rotor discs or setting rings. The rotor position can be adjusted if necessary with the threaded stop at the left-hand end of the front key shaft. Note that the adjuster will only push the shaft to the right - if the screw is loosened, the shaft must be pushed to the left by hand from the right-hand end.
  200. Clear the rotor and check the setting mechanism. Set a full row of each digit in turn to verify all positions. The mechanism should operate quickly and easily. It may be necessary to make further fine adjustments to the escapement position to provide clearance for the setting arms.
  201. When all is working correctly, tighten the lock nut on the escapement adjuster and the set screw on the front key shaft.

  202. Carry rotor assembly - pressed discs with separate cams
  203. Observe that the carry rotor discs and cams are numbered. Parts with are the same numbers are the same in both sections. The accumulator side has discs 1 to 12, while the counter side has 13, 1 to 4, and 9 to 11.
  204. Start with the counter section. Fit the key to the keyway and stand the shaft upright. Fit the end plate 13 with recessed side down (towards the drive gear). Follow with cam 1, two spacer rings, and disc 1 with recessed side down.
  205. Fit the remaining cams, spacers, and discs in the same manner. Fit the second 11 cam at the end, then the nut. Check that the carry pins and cams all proceed in sequence, and that the pins move and return easily. Tighten fully, but do not over-stress the brass core.
  206. Assemble the accumulator section in the same manner on the large shaft, starting with cam 1, two spacers, and disc 1 with the recessed side first. Finish with the small un-numbered cam and nut. Check that the carry pins and cams all proceed in sequence, the that the pins move and return easily. Tighten fully, but do not over-stress the brass core.
  207. Place the counter drum and drive gear onto the shaft. Observe that one tooth on each gear has a small dot on on the tip of one tooth. Line up the high points of the cams in each section, then rotate the outer gear to align the two marked teeth. Align the pin holes, support the hub of the gear, and press in the rolled pin. Check that the counter drum turns freely.

  208. Carry rotor assembly - one-piece pressed discs
  209. Observe that the carry rotor discs are numbered. Parts with are the same numbers are the same in both sections. The accumulator side has discs 14 to 25, while the counter side has 14 to 17 and 23 to 25.
  210. Start with the counter section. Fit the key to the keyway, then the end plate with recessed side down (towards the drive gear). Follow with a thick spacer ring and disc 14, recessed side down. Fit the remaining discs and rings in the same manner.
  211. Fit the tabbed washer and nut. Insert the alignment rod from the nut end, tap the assembly on the bench to settle the discs, and tighten the nut. Fit the C-clip to the end of the alignment rod.
  212. Assemble the accumulator section in the same manner on the large shaft, starting with a tabbed washer and disc 14, recessed side first.
  213. Place the counter drum and drive gear onto the shaft. Observe that one tooth on each gear has a small dot on on the tip of one tooth. Line up the alignment rods on each section, then rotate the outer gear to align the two marked teeth. Align the pin holes, support the hub of the gear, and press in the rolled pin. Check that the counter drum turns freely.

  214. Carry rotor assembly - die-cast discs
  215. Observe that the carry rotor discs are numbered. Parts with are the same numbers are the same in both sections. The accumulator side has discs 1 to 12, while the counter side has 1 to 4 and 10 to 12. The half-round bar is pinned to disc 4 in both sections.
  216. Start with the counter section. Place the shims onto the hollow shaft, then fit the end plate with recessed side towards the drive gear.
  217. Place discs 1 to 4 onto the shaft with the flat sides towards the gear. Note that the keyway is angled slightly to ensure that the discs can not be fitted upside down.
  218. Place the half-round carry lever reset bar edgewise into the cut-outs, twist it into position, and push it towards the gear to engage the pin with the slot in disc 4.
  219. Fit discs 10 to 12. Check that pins all proceed in sequence, then fit the washer and nut and tighten.
  220. Assemble the accumulator section in the same manner on the large shaft, starting with the shims and disc 1.
  221. Fit the smaller shim onto the thin end of the shaft, then place the counter section and drive gear into position.
  222. Observe that one tooth on each gear has a small dot on on the tip of one tooth. Line up the reset bars on each section, then rotate the outer gear to align the two marked teeth. Align the pin holes, support the hub of the gear, and press in the rolled pin. Check that the counter drum turns freely without end play, and adjust the shims if necessary.

  223. Carry rotor installation
  224. Check the fit of the two rotor bearings into their mountings. The bearings are both 7mm wide; the right-hand bearing may be marked with a dot. Ease any scrapes or nicks around the ouside of the bearings or in the housings in the side plates. Remove the bearings.
  225. Set the winding handle in its stop.
  226. Reset all the carry levers by pressing them down at the rear detent bar.
  227. Fit the original shim(s) to each end of the carry rotor shaft.
  228. Locate the timing dot or the inverted V on the inside of the right-hand side plate, just above the housing for the carry rotor bearing.
  229. Hold the rotor with the two marked gear teeth upwards. Insert the right-hand end into the bearing housing, align both marked teeth with the inverted V, engage the gears and start the bearings. Check the alignment and repeat as necessary.
  230. Adjust the shims and end stop (if present) so that the resetting cams on the carry rotor are aligned with the carry levers (best seen from above). Check that the carry discs are not rubbing on the sides of the levers. Align the bearing mounting holes and fasten with 3 screws M3x8, or M3x9 for the adjustable cover plate at the left-hand end of the C1-13. Leave the rotor shaft with a minimum amount of end play.
  231. Clear the setting rotor and counter and turn the handle forward. Note that the two carry drums rotate in the same direction and the counter counts forward. Clear the counter, turn backwards, and note that the drums turn in opposite directions but the counter again counts forward.
  232. Clear the rotor and registers. Set a 1 into the rotor and give the handle one backwards turn. Check that the accumulator ripple carry proceeds smoothly to the end. Turn clockwise twice and check that the accumulator resets and the counter carries to all 9s.
  233. Attach the bell to the rear of the left-hand side with 1 screw M3x8 and spring washer. The mounting hole is usually off-centre so that the bell can be turned to adjust the tone. Adjust the bell hammer if necessary by bending the wire.

  234. Finishing off
  235. Exercise the machine extensively and confirm that all functions are operating as expected. Correct any defects as necessary.
  236. TK: Invert the machine. Fit the rubber mat and retainer plate and fasten with 4 large shouldered screws.
  237. NTK and C1-13: Attach the rubber feet to the bottom cover. Attach the short spring clip on the left-hand side and the long clip on the right. (On the NTK the low side is the front; on the C1-13 the nameplate is at the front). Glue the four corner mouldings in place.
  238. NTK and C1-13: Fit four rubber bushes and spacers into the bottom cover from underneath, then fit the remaining four from the top, flanged side down. Invert the machine and attach the base with 4 screws M4x22 and dished washers. The screw heads go in the dished side of the washers.
  239. NTK and C1-13: Lay the machine on its back and attach the keyboard backing plate with 4 screws M3x6.
  240. Fit the register mask and engage the red indicator flag with its operating lever. Check that the flag is hidden when the counter is cleared, and fills the window after an initial negative turn. Bend the lever slightly if adjustment is needed. Fasten with 1 screw M3x6.
  241. Set a row of 9s in the rotor and press the division setup key.
  242. Examine the operating arm on the sliding position indicator plate. Note the forked end and the offset vertical tab below. Insert the arm at the right of the rotor, so that the fork sits around the counter drive shaft and against the right-hand side of the quotient coupling. The offset tab passes through the cut-out in the quotient coupling end plate and sits against the left-hand side, so that the indicator plate will follow the movement of the coupling in both directions.
  243. Engage the supporting cross-bar with the tabs on the top front of the indicator plate and fasten with 2 screws M3x8 (or the special countersunk or shouldered screws if originally fitted).
  244. Slide the rotor mask up under the indicator plate. Align the cut-out with the numerals and fasten with 2 screws M3x6.
  245. TK: Cut and fit new register windows from suitable clear plastic packaging.
  246. TK: Fit the side, back, and top covers and the clearing handles.
  247. NTK and C1-13: Fit the right-hand filler plate over the winding handle. Remove the clearing levers and fit the top cover. Ensure that the three tabs on the filler plate are properly engaged around the cut-out. Press down firmly to engage the clips, then replace the clearing levers.

Appendix 1 - Assembling the rotor linear bearing.

Rotor linear bearings

The photo opposite shows the two styles of ball sleeves used in the Facit linear bearings (click to enlarge). The TK and NTK have a perforated sleeve with five parallel rows of balls. The C1-13 has a solid sleeve with the balls arranged in a spiral. The perforated sleeve can be assembled fairly easily. Three different methods are provided for the solid sleeve. In all cases the work should be done over a large tray or dish so that dropped balls can not escape. Although the shaft is metric 9mm, lost balls are Imperial 1/8 inch.

Perforated sleeve (simple).

  1. Drill a 9mm hole in a block of wood and stand the rotor shaft upright.
  2. Plug the pin hole at the end of the shaft so that it cannot trap the balls. Use a chip of wood or a strip of rolled paper, and leave it level with the sides of the shaft.
  3. Place the rubber buffer disc against the end flange. If the disc is hard or broken, a new one can be cut from 1.5mm neoprene sheet.
  4. To assist in holding the ball sleeve centred on the shaft, a simple split sleeve can be made up from any suitable material. Alternatively, wrap a strip of paper around the end of the shaft until it it is thick enough to hold the flanged end of the ball sleeve centred.
  5. Slide the sleeve(s) down until the first row of holes is just above the end of the shaft. Insert the balls through the adjacent holes and roll them into position.
  6. Slide the sleeve down and repeat for the remaining rows. The paper centreing strip can be removed when the first two rows are in place.
  7. The "special tool" method (below) can also be used with the perforated sleeve, but the balls need to be inserted one row at a time.

Solid sleeve - basic method (difficult).

  1. Drill a 9mm hole in a block of wood and stand the rotor shaft upright.
  2. Plug the pin hole at the end of the shaft so that it cannot trap the balls. Use a chip of wood or a strip of rolled paper, and leave it level with the sides of the shaft.
  3. Place the rubber buffer disc against the end flange. If the disc is hard or broken, a new one can be cut from 1.5mm neoprene sheet.
  4. Apply a small amount of thick grease to the inside of the first 6-8 holes in the flanged end of the sleeve. Hold the sleeve vertically and place the first ball into position from below. Use tweezers, a greased stick, or lightly magnetised screwdriver. Repeat for as many balls as will stay in place (at least the first 5 or 6).
  5. Carefully lower the sleeve onto the shaft until the top of the shaft is level with the bottom of the next hole. Roll in the next ball, lower the sleeve, and continue to the end. Be careful that the balls do not roll out through the two larger holes.
  6. It is necessary to keep the sleeve centred on the shaft and to avoid tilting. It gets easier after the first six balls are in place.
  7. Wash out the thick grease and apply light oil on completion.

Solid sleeve - simple tool method (easier).

Sleeve bearing tool 1
  1. Plug the pin hole at the end of the shaft so that it cannot trap the balls. Use a chip of wood or a strip of rolled paper, and leave it level with the sides of the shaft.
  2. Place the rubber buffer disc against the end flange. If the disc is hard or broken, a new one can be cut from 1.5mm neoprene sheet.
  3. To assist in holding the ball sleeve centred on the shaft, a simple split sleeve can be made up from any suitable material. The split sleeve should fit easily between the shaft and the ball sleeve. A small notch at the top allows the tool to be inserted around the first ball to provide deeper engagement.
  4. Place the split sleeve around the shaft and tape the two halves together. The sleeve should slide smoothly along the shaft without binding.
  5. Place the ball sleeve over the split sleeve so that the first hole aligns with the small notch. Tape the two sleeves together, without covering any of the ball holes.
  6. Slide the sleeves up until the top of the shaft is level with the bottom of the first hole.
  7. Hold the shaft on a 45° angle with the first hole at the bottom, then roll the first ball in from the top. Be careful that the balls do not roll out through the two larger holes.
  8. Lower the sleeve to the next hole, rotate 60° to bring the second hole to the bottom, and roll in the next ball. Continue to the end.
  9. Remove the tape and split sleeve.

Solid sleeve - special tool method (simple).

Sleeve bearing tool 2
  1. The easiest way to assemble the bearing is to make a special service tool. The sleeve and balls are assembled on the tool, and then transferred onto the rotor shaft.
  2. Turn a length of metal, wood, or plastic rod to fit neatly inside the ball sleeve. Drill one end 9mm diameter and deep enough to cover the tapered pin hole when placed over the shaft. Cut six grooves lengthwise for 150mm from the drilled end. The grooves should be about 4mm wide and 2mm deep, so that the diameter across the bottom of the grooves is the same or just slightly larger than the rotor shaft (about 9.2mm is a good fit). The plain end is then chamfered to produce the 6-pointed star at the front. The tool does not need to be very precise. The wooden example illustrated was cut with a 4mm round burr in a Dremel tool mounted on the toolpost of the lathe, and indexed by guesstimation from the chuck jaws. (Some years after inventing this tool, after many tedious overhauls, I was surprised to find a very similar tool illustrated in a Facit service manual).
  3. Place the rubber buffer disc against the end flange. If the disc is hard or broken, a new one can be cut from 1.5mm neoprene sheet.
  4. Hold the tool vertically over a tray with the pointed end up. Start the flanged end of the ball sleeve onto the tool so that the first hole aligns with the top of one of the grooves. Drop a handful of balls into the sleeve and push the tool upwards. With a little bit of jiggling, the balls will magically appear in the correct holes.
  5. Place the drilled end of the tool over the shaft so that it covers the tapered pin hole, then slide the ball sleeve off the tool and onto the shaft.


Original text and images Copyright © John Wolff 2008-2022.
Use at own risk; beware of errors; suggestions for improvement welcome.
Last Updated: 10 June 2022 - major revision.

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