Ray Mackay


There are Web sites throughout the world containing pictures of mechanical calculating machines. Not many such sites have details of the internal workings of such machines, although collectors and hobbyists like to endeavour to restore them. Without specific information this task can be risky and damage to the machine may result. The enclosed pictures and drawings The enclosed pictures and drawings cover a model WM (War Model) Comptometer and are provided to assist such hobbyists and enthusiasts. The information should be used in conjunction with information at

The author wishes to thank Philips for allowing the use of a Digital camera for the pictures. It is worth noting that the largest problem encountered was the removal of pivot shafts that had been bonded to the parts by years of inactivity. These were removed as the job progressed by copious use of CRC 2.26 or CRC 5.56 sometimes leaving the shaft and its parts to soak overnight. The shafts were then gently hammered through with a similar size 'follow through shaft', or one a size smaller. After removal the shafts were cleaned of all residue using very fine Wet and Dry Emery Cloth soaked in oil. The shafts were then replaced and dismantling of the area concerned continued in the normal way with follow through shafts 'borrowed' from earlier in the process. Vagabond is not sending me some follow through shafts to assist me in other projects.

compt01.jpg (6941 bytes)This image shows the machine with case removed ready for starting on the disassembly. The thumbnail pictures, although of poor quality illustrates the content of the larger JPEG image for those who wish to collect and modify the images

GET 'Larger images of the thumb nails are approx. 20~25K size', an important factor to know if you are grabbing any of them,

compt02.jpg (7560 bytes)The Numeral wheel shutters and subtraction cut off lever were removed and placed in order in front of the machine. These will later be moved in order to one side so that we can continue the saga.

GET 'details of machine with Numeral wheel shutters and Sub-cut-offs removed'

compt03.jpg (6643 bytes)The safety shaft, a suitable piece of flower wire of approximately the right gauge, was inserted into the rackframe actuating cranks. The front toggle shaft was removed in preparation for the removal of the rock-frame. All the Intermediate gears were dropped down alongside the Carrying gears and the Rockframe and Intermediate Gear shafts and follow through rod removed. This allowed the rock frame to toggle forward as in this image. The two blank intermediate gears were deliberately moved from the two right positions to the left positions for the purpose of clarity.

GET 'Show larger image of Rockframe forward'

compt04.jpg (7214 bytes)By rocking the 'RockFrame" on the front Rockframe toggles it pivots under the frames front upper spacers. It should toggle freely and can be pivoted backwards and forwards a number of times to allow familiarisation to give you the feeling for removal. Once confident rock the frame forward and remove it; as illustrated. Very likely the carrying gear shaft and locking dogs will be gummed up but this does not concern us at this time. If you remove the intermediate gears you can turn the Rockframe about in your hands, quite safely to examine it. Later we will describe its function. You will note in this image the first four numeral wheels and numeral wheel shutters have been removed. This was done merely to illustrate that the Rock-Frame can be removed with or without the Numeral wheels in the machine.

GET 'Rockframe is removed and placed on bench top'

compt05.jpg (5638 bytes)All the numeral wheels have been removed and placed to one side with the parts removed earlier and we are moving in to position to remove the Carrying Bell Cranks, Latch Lifters, Backstops and Backstop Springs. Look into the mechanism as this time and note the backstop springs pivot on the shaft inside the actual backstop bearing. The springs are under tension and if the shaft was to be removed with due care the springs would fly all over the place. You can if you wish unlatch all the spring ends from under the frame. I elected to use a follow through shaft place my hand over the front of the column I was working on and slid the shaft out. Almost invariably the spring would hit my finger, the backstop would drop under the machine with the sprint, the Bellcrank would swing forward on its spring and the latch lifter would also fall out. Carefully unhook the Bellcrank spring at the bellcrank, or if you wish use a follow through shaft and release the top end of the spring (this is harder). Place the parts in columnar order at one side. If you wish you can check if the rollers on the bellcrank turn freely. The hair springs are easily pulled of the pivot stud but this is not necessary.

GET 'Showing numeral wheels removed'

compt06.jpg (6419 bytes)The accumulators can now be removed by roving the shaft to the left one column at a time. In this image we show four accumulators dropped down ready for placing at one side in columnar order. Before removing the ALL the accumulators it is worth while dropping three, or four as in this case. Pull the accumulator apart and note it consists of a pinion and ratchet, and lantern wheel (or pin wheel) attached to a second gear. The pinion and accumulator are held together by a 'sintered bronze', I assume, tube. The ratchet is attached to the body of the accumulator and a fine spring provides the tension. Note also A VERY IMPORTANT POINT the Pinion has a deep tooth. This tooth must be one tooth forward of top dead centre on reassembly; when the segment levers are up. Familiarise yourself with the deep tooth and its position before removing all the accumulators. NOTE also the bellcrank springs, take care not to catch these on your clothes and stretch them.

Four accumulators are dropped and deep tooth examined for future ref...

compt07.jpg (6703 bytes)The accumulators safely out of the way we can now tackle removal of the keys and keyplate. The keys are held in place by keypieces with a key piece spring that also works at the return spring for the individual keys. NOTE the springs have different tensions in each position, thus a nine key spring is much lighter than a one key. The springs can also inflict considerable damage should they hit the face or eye as you work. So wear specs' or 'safety goggles' as you remove the keyspring or flex the keypieces. It is well to note that the keypieces themselves do not have to be removed to remove a key. With a pair of fine short nose pliers you can grab the left-hand leg of the keypiece with the spring inside the frame piece and tilt the keypiece the key can then by lifted out of the plate. This is repeated until you have all the keys removed. In this case four rows have been removed. The machine was stood on its rear end during removal of these rows. Vagabond often refers to the numeral fill oozing from the keytops; note this on the No 2 Keytop.

Shows four columns of keys removed'

compt08.jpg (9193 bytes)Once all the keys are removed you will find the top plate is held down on to the frames by three shafts with folded ends, in the case of ex-sterling machines, and two shafts in the case of machines that were always decimal. Removing these shafts allows the keyplate to be removed (on an 'F' 'H' or 'J' machine you simply remove the keyplate screws, after removing the keys, and trip the toggle on either side of the keyplate at the rear. It should be noted that model 'H' and 'J' are easier to work on as the square frame does not tend to want to go its own way and the machine fall over backwards. On the 'F; the accumulators section is somewhat different, Vagabond is to send me a machine to refurbish and this may be a future project. All the manual Comptometer machines are similar and once you have seen the workings of one the rest are not so difficult. As the models climbed up the alphabet they got progressively more complex and the WM in this project is a difficult as you are going to get, the 3D11 being the last manual Comptometer made was the next model.

A 'shot' showing all those things you wanted to see but always remained hidden...

It is the authors plan to continue this project and explain the removal of Segment lever, Keystop levers and Trigger mechanism including showing how to check the adjustment of the various parts. To prepare you for the next run some images are attached for those wishing previews without any text. Later I will add the text. As you will note the machine was pulled right down to its frame and reassembles adjusting and checking as the machine was refurbished. For those who had doubts it now clicks over like a fine watch although it still has the dreadful smell of rancid oil. Normally all the parts would have been washed out in mixture of Kerosene & Shellite or some similar cleaning fluid. Although the challenge was there my desire to avoid getting filthy dirty was greater than the desire clean the parts to provide the information.

Later more images will be added. It is also planned to do a similar project using a Walther and who knows maybe Busicom and some electronic machines, starting from basics. THE FUTURE IS AHEAD and retirement may give me the time, although current indication suggest it will not

Clearing handle side removed...

Segment lever springs and trigger bell crank...

Segment Lever coming out from under machine...

Segment Lever Out...

Segment Lever and Part Keystop Lever...

View from above showing all rows same or similar on left are the trigger bell cranks and springs on centre horizontal retainers and right accumulator locking hooks, accumulator pinion ratchets...

It now time to finish for the day. I will continue later. The eyes and mind get tired. For those who use Telepro they can download all the images and have a preview. Some images still have to be uploaded and this will be done as soon as time allows For others who are especially interested they tell me patience is a virtue.

Section last updated 16th May 1999 by Ray Mackay


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