Replacing a pin with an M2 screw on the Mignon index typewriter

To take apart the actuator arm of a Mignon index typewriter, a soft-steel pin has to be removed from the hollow main actuator rod. This 2mm pin holds the 'plug' with the ball-on-a-needle that is the vertical type-alignment bearing. Only when that is removed, can the parts be taken apart further; the actuator arm in bits:

This pin is in an awkward position. Pins are unpleasant to remove anyways, but this pin is very close to the delicate casting of the arm-assembly. Any stray hammer-tap on that part and it would shatter for sure. 

Also the horizontal bearing-tube is concerning; this also seems to be a fragile Zamac casting. Over time the material can swell and the part will then be very hard to slide out of the cast-iron forked-lever. On this machine only filing down of the centre-section was needed to get it out.

Putting it all together again, the needle-plug was fixed in the actuator-rod not with the pin, but with an M2 screw and nut. 

The brass M2 screw is a very tight fit (scraping), leaving no play between the parts. (Any play would introduce vertical type-alignment variation.) This screw is not authentic, but is normally not visible from the outside. More importantly; an M2 screw won't need hammering close to fragile Zamac castings and will make future repairs so much easier.

Also the soft pin that locks the horizontal-rod (right-end) was replaced with an M2 screw. The M2 nut is an exact fit in the slot of the horizontal-rod, making it an easy replacement. Again not authentic, but not very noticeable and much easier for future servicing. (Well, if there ever would be any, of course).

Most index typewriters were low-cost flimsy affairs, but the Mignon actually has a heavy cast-iron frame and is overall solidly-built.

It does have far fewer parts than a standard typewriter (and was about a third of the price), but it does have a similar build-quality. (Just wish that they hadn't used Zamac and pins!)

American Typewriters catalogue, but who is it from?

A 'prospectus' or catalogue of 'Amerikaansche Schrijfmachines', i.e. American Typewriters.

And that's what it is, showing standard office typewriters from the major American makers. The booklet opens with the point that instead of only one make they sell all brands, so are better positioned to recommend the machine most suitable to your specific business needs.

The pages that follow have an illustration of a machine with a paragraph explaining that machine's commendable aspect. The major brands and types are all there, including even the Demountable and an Oliver. From the machines and features shown, the catalogues will date from about 1923.

Notable that the Woodstock has the briefest paragraph; unlike all other machines it gets no mention of a differentiating feature. It's a typewriter.

For private use or for small firms, also one portable machine is included; the Corona 3 folding portable.

This booklet may have lost an outer cover, because nowhere is mentioned who this office supply company is! There is no name or address anywhere. The staples however are tight around the current set of pages, no hint that a page or card cover is missing. When being given out back in 1923, it would have been accompanied by a letter, business-card or company circular - but even so, it seems strange to not have any mention of the trading company anywhere on the 16 printed pages.

There is on corners a medallion logo with an L, C, M and an '&'. That may well have been the initials of the trading company, but am mystified who that could have been.

This LC&M (or L&M C or etc...) becomes even more mystifying when seeing that this same logo is also on the back-cover of a ~1920 Comptometer instruction manual. 

To my best understanding Felt & Tarrant had their own offices in Amsterdam to sell and service Comptometers. The manual also is clear that it's by the Felt & Tarrant company in Amsterdam.

Was the Amsterdam office of Felt & Tarrant in reality a local dealership, i.e. a trading company also masquerading as a local F&T office? Or was the Felt & Tarrant office in Amsterdam selling a sideline in typewriters too - they already had a sales staff visiting larger offices and had repair capabilities. (Or is the logo merely a printer's way of making his mark?)

Either way; it's a nicely illustrated catalogue of American standard typewriters with their differentiating points - now available on The Archive. 

And it's also a little mystery; who was this published by? 

With archives being placed online, perhaps another booklet or newspaper advertisement will show up in time to clarify the logo :)

Refurbished Comptometer model H

This Comptometer model H got refurbished, again, in 2023 :)

The old, drab paint from a late 1930ies or 1940ies re-build was stripped from the panels.

The top-panels were re-painted in a matching brown copper-colour.

New keys were manufactured.

The new keys were fitted to cleaned key-stems.

The decimal-markers riveted back on the front display-cover.

The top-cover place back onto the mechanism and keys re-mounted.

New window and feet improvised and fitted.

And then the whole machine is put together again, clean and cosmetically very acceptable.

However, the column 6  had been malfunctioning - caused by sticky old lubricant. Closely watching what was going wrong to identify the cause (peering into the mechanism, operate machine, use flash-light). Then some prodding with a wooden skewer to get suspect parts unstuck. This fortunately confirmed that old grease was the cause. Hopefully with frequent exercise the problem will be solved, exercise is anyways important for all mechanical calculators. (Am not confident to take a Comptometer mechanism fully apart to get at the levers inside the 6th column!)

The view from the side gives a pretty good indication of the density of levers, rods and springs throughout the whole machine. It is amazing in its complexity, very clever - mechanically rather marvellous :-)

For example the holes-pattern in the intermediate gear in the register (only a small section visible) is functional (less mass, more speed) - it also is a mechanical detail that's just very nice to see.

This particular model H had been bought (cheaply) in a rather bad condition. On the (bad lighting) images of the listing it had looked fine, but seeing it in daylight after picking it up its drab finish was clear.  That, with  its decaying J-model plastic-keys were evidence that this was older rebuild.

It probably was rebuilt and re-sold already in the late '30s or 1940s. The calculator itself has serial number 209,945 and dates from around 1921. These were expensive office-machines (entry-model was about twice the price of a large standard typewriter). There was a market for rebuilt Comptometers, both by the manufacturer and third-parties. Rebuilding was especially common in the immediate post-war period, but also happened in the 1930s - the F&T company even advertised that they would not guarantee rebuilds by others.

The internal mechanism of this specimen had luckily survived quite well; almost no rust and clean with relatively little gummed-up old lubricant. Overall, Comptometers are amazingly durable - especially considering their complexity and the amount of fine-adjustments in the mechanism. 

So, after the initial disappointment of buying a badly-ageing rebuild machine; now it's a shiny clean Comptometer model H that calculates just fine. Perhaps almost as clean and as fast as it was back in 1921 :-)

Improvising new feet for the Comptometer and a window-sheet

Comptometers have feet - although today many are sat flat on the table like a shoebox, they'd originally have had rubber feet. These feet were press-fits into holes in the bottom of the case, found in grey or black and usually completely decayed. They're either completely lost or pressed flush with the base of the machine, the rubber being pushed with a bulge into the interior. (Remnants of a foot can also sometimes be found floating about the inside of a case. Or stuck to the cork lining.)

To make a quick-fix set of feet, these were built-up from rubber. Of itself, the feet could be a good candidate for 3D printing replacements (FDM, PU rubber), but disk-stacking works gooed-enough. Using small drops of cyanoacrylate glue, disks of 10mm (one), 16mm (one) and 18mm (several) were glued together in a stack.

Using hole-punches, disks are cut from a sheet of 2mm rubber. Place dot of glue, place disk on top, centre properly and then press together firmly. As final element, self-adhesive felt-pads to get 'dampening' feet. 

These improvised feet are almost a press-fit into the recessed holes with the 10mm disk (10.5 would've been good, but no such hole-punch :-). To keep them in place, some extra hobby-glue is good enough (not cyanoacrylate!). This stacked method is a quick, improvised alternative to 3D printed feet. They simply work and Comptometer feet are not too visible anyways.

The windows over the numeral-wheels are covered with a single sheet of celluloid. The original sheet of celluloid on this machine was very yellow. Now that the keys were bright again, also wanted to have clear windows over the numeral wheels. A strip of 0.2mm thick clear-plastic was cut from a sheet - it was sold as 'mica-sheet' for crafting. No idea what plastic it really is, but it's fairly clear and can be cut easily. It is also flat, the window must be curved to fit under the front window-panel.

To create the curvature needed, it was placed over a ~33mm diameter tube held in place with elastic-bands. A hair-dryer then was used to heat the new window-strip to have it relax and settle in a curve. This sort-of worked; it is correctly curved, but it got some extra 'wrinkles' as well from the elastic bands. 

With better clamping of the sheet and better temperature control (oven?) this method could probably be improved on, but the quickly improvised new window looks fine. More importantly, it works: gives a clear view of the numerals and will stop dust and dirt getting into the mechanism.

August 2023 typewriter ^D^D books safari

Last weekend's tour of the local thrift stores yielded 'the usual suspects'. The same gathering of Erika's that's been hanging around one store, and a couple of wedges at another store that have been there for ages.

Also having a browse through the books-section (as always), this time there were some neat and unexpected finds there! A pristine 1904 copy of a very local Frisian language 'Fryske Husfrjeon' with local lore - and more interestingly a history book 'Friesland in 1813' (in Dutch) about the end of the Napoleonic period in Friesland.

This book describes how the end of the French empire played out in Friesland in the fall of 1813. It was written and published to commemorate the 50th anniversary of the restoration of the Netherlands. From the title-page, this looks indeed to be an 1864 printing.

Having been compiled relatively shortly after the events, the writer would still have been able to talk to eyewitnesses. The stories do indeed have detail and names of people. Apart from the regiments and militias that were raised and how every mayor behaved, also human-level stories. 

E.g. how the ~3000 refugees that passed through Harlingen between November 14 and 17 fared. And how a few Cossacks arrived there on the 28th and requisitioned remaining French supplies (coffee, sugar) and auctioned off the local naval supplies that night.

Or the regime-change in Lemmer; news of events elsewhere triggered unrest and the French gendarmes and customs officers quickly made themselves scarce. The guard-booths were tossed in the harbour by the crowd.

When after few days no French forces appeared, the crowd burned an effigy of Napoleon and made the mayor raise the Dutch flag on the tower. And again the selling of coffee and sugar by then-arrived Cossacks, captured from a merchant ship that was still in the harbour. (By the way, not everywhere the change was so swift; in the province of Groningen the French commander of Delfzijl refused to believe the defeat of Napoleon and held on.) 

There are copies of this book in the Frisian archives of course, I suspect it was printed in fairly large numbers. There are a few editions of this work, all edited/compiled by Wopke Eekhoff. He was a book-seller and publisher in Leeuwarden and in 1838 appointed as the official city-archivist of the city. He also was longtime active in the Frysk Genoatskip, the Frisian historical society. Compiling a work like this history book would have been well within his abilities and knowledge.

Perhaps not too common in thrift-stores, but today this book is available in its entirety online at The Archive for easy browsing.

Looping back to the original subject of the safari; no interesting specimens spotted. Typewriters are pretty much all beige in thrift stores today. For example a Scheidegger branded machine of unclear origin. It had future-minded branding as a 'Eurostar' and '2000' also must have sounded advanced. Looking at it, had classed it as a manual machine, but the branding explained that it was an electric. (And indeed it has a carriage-return key - also has a backspace, that I'm sure will not erase ;-)

Otherwise the wedges and electrics are getting to be the staple of second-hand stores. Likely all still functioning fine, all left there for someone else.

Fitting the key-plate back on the Comptometer and re-mounting keys

To start the re-assembly of the Comptometer, they newly-lacquered key-plate is mounted back onto the mechanism. Before doing that, the red controlled-key button must be mounted (insert stem from underneath through hole and press the button on the stem). 

Also the name-plate has to be mounted first; this is screwed not onto the key-plate, but it is screwed into large washers that also serve to hold the cork lining in place. In practice with old machines, these washers will be 'glued' onto the cork and the plate could perhaps be screwed of safely - however there is also a risk the large washer will drop free and deep into the mechanism (and then no way to re-mount the name-plate without a full disassembly and taking off all keys!).

The key-plate having been prepared, the front of the plate is hooked under the two tabs at either side of the carry-suppression levers.

At the rear of the mechanism on the sideframes, there are two tabs that can swivel up. With these 'clicked' out of their position and angled up at about 30 to 45 degrees, these swivel-tabs have fingers that will catch under the rim of the key-plate as it is brought/rotated down onto the mechanism.

With a 'click', the key-plate will sit flat on the mechanism and all the little tabs should protrude evenly through all the little aligning slots of the key-plate. With the four screws (on an 8-column machine) right behind the 9-keys slots the key-plate is firmly fixed on the mechanism.

Then the keys can be re-mounted - one column at a time. The order does not matter too much, unless the holding-levers and springs on the bottom of the machine were completely taken out; then it is best to work from high (left) to lower (right) columns because a lower column lever-leg is placed on top of the lever-leg of its higher neighbour.

Starting with the 9-key and working down turned out to be the practical way to re-fix the keys. Insert from the top, wiggle gently and the curved end of the key-stem will show up near the V-shaped lever that has to catch it (circle).  

To make the curved end drop into the hole of the V-shaped lever, it can be tilted by unhooking one leg. Then re-placed and the torsion-spring again locked under its tab (arrows). The 9-keys are trickiest to get proper access to for this manoeuvre and small pliers may be needed to get at/tilt the lever, but otherwise its fairly straightforward.  It just needs to be done 72 times (on an 8-column machine).

Comptometer decimal-makers re-fitting

After painting of the front panel, the decimal markers have to be re-fitted. On Comptometers these are originally fixed to the cover with rivets - actually F&T used rivets with a shoulder to be able to rivet and still be able to swivel the little markers.

The decimal markers were first cleaned and again filled-in with black paint. To mount them back whilst limiting the risk of damaging the new paint finish, aluminum rivets (instead of steel) were used. A batch of 2mm diameter, 4mm long hollow-shaft aluminum rivets was bought - these have a head that is too large, so 8 rivets were turned/filed down to heads of a bit over 3mm diameter. (Should've gone smaller, with hindsight.)

The holes in the cover were filed were needed to take the 2mm rivets. Some M2 washers to support the rivet on the inside, except for the locations that have the window spring-clips acting as washer. A spot of petroleum jelly added to the holes before fitting the rivets to act as rust-prevention and lubrication.

The aluminum is soft enough to allow the rivets to be fixed without having to hammer them; they can simply be squeezed flat with pliers. Pressing with pliers (protection over the heads to prevent marring) allows the press-fit to be tweaked so that the pointers move easily, but still with a little friction. When squeezing tight, the heads however do also flatten and spread out a bit. They're not too disturbingly large, but still a few tenths of a mm larger than they should've been. (Next time, will make the heads smaller to start with.)

Result is that the pointers are again fitted; they look credible and move fine without any scratching of the paint - which was the main concern :)