Comptometer E - part number J281 celluloid window

Perhaps the celluloid window-sheet of a Comptometer was part number J281. During cleaning and repair of my Model E Comptometer, noted a crisply embossed number:

The window sheet may well be original, although this Comptometer clearly was serviced and repaired in the past. So it may be a replacement, but probably done by a (the) company servicing - perhaps in the 1930s using a Model J part? Maybe the spare-parts lists, drawings or Bill of Materials of a Comptometer will turn up in the future. 

The snippets from a repair manual of 1919 on Brooke Boering's site confirm that Felt & Tarrant used three-digit numbers, some with a letter pre-fix. For example on a Model H the subtraction (cut off) lever is part T604, a toggle pivot link shaft is part 865. Perhaps we can now add that the curved celluloid sheet is part J281.

The Model E was a much more complicated machine than its predecessor C. With this model Felt and Tarrant added error-detection and control mechanisms that not only increased cost, but also made it relatively fragile. (These new feauters would likely have been considered essential by the company in their fighting off the direct competition of the Burroughs Calculator that launched 1912.)

The Model E machine's frame is noticeable thinner than the preceding Model C, comparitively flimsy. The keystems with the many corners (stress concentration at bending) and narrow sections are vulnerable too. This specimen indeed had a broken key-stem and the top plate had lifted from the holding brackets at the front. This distorts the case and can jam the cut off levers.

Even though from the classifieds ad it was clear it was blocked, had a broken keystem and was rough (and dirty!), it also was 25 Euro and a Model E: so did a pick-up of the machine. Model E's are not all that common, that likely is because the E is not as robust as other Comptometers - it is rather fragile, in fact. Even though thousands were made (7700?), the survival rate of the E is expected to be much lower than that of e.g. a C or an F model.

To clean and repair, the usual steps for a Comptometer; the mechanism was taken out, all keystems removed and everything was cleaned. Taking out all keys enables cleaning also of the top plate in the key-area, often has the accumulated dirt of many decades. The Model E key-stems can only really be cleaned when out of the machine. 

The broken 9-stem was given a 'fix'. It really should be hard-soldered or brazed, but not (yet) having the tools for that it was first soldered. To compensate a bit for the soft joint and anycase to mitigate the butt-joint a splint was added. Slots were sawed in both ends and a sliver of iron inserted. (The lower end of the broken keystem was initially thought to be missing - simply could not be found in the case or in mechanism around column 9 - only when re-inserting column 6 did this bit drop out with a tinkle. Lucky!)

The soldered joint then sanded smooth and the key can be fitted back into the machine. This weak keystem not placed in its original corner position of column 8, but swapped with the intact stem of column 7.

This joint is too soft really, but should hold for a few years until a proper hard-soldered (or welded) repair can be considered. 

Again complete and fully functioning - when taking care to operate gently. Re-assembly also needed care, the order of tightening of screws of the case making a difference between columns being blocked and everything working as it should! Another confirmation that the Model E is a fragile machine - at least this specimen.

This particular machine was maybe one of the last to be exported from the US to Holland, before shipping became dangerous and expensive. The nameplate is the factory 'generic' in English without any patents.

The rear of the case lists the patents, from the first 1887 to an October 1913 patent.

This Comptometer was used - judging by the wear it was used heavily. The rust on the sides shows where hands have rubbed off the protective lacquer and even the copper coating to expose the steel. The machine was also serviced and repaired in the past. Several replacement screws in the case show it was taken apart completely at least once. The broken keystem had solder remnants; so when that initially broke the machine was still valuable enough to try a repair to keep it in use.

The new Controlled Key Comptometer Model E - repaired! (And fragile.)

Blickensderfer ink idea - more testing

Having found a cheap and plentiful source of very small quantities of oil-based ink, some more experimenting was done. Especially some colored inks; a discount-store had a brand set of colored ballpint pens for a few Euro.

These are very easy to take apart - twist and pull gets the top off and it all comes apart. The nib can be pulled out of the white tube easily (and pushed back too, they re-assemble equally easily).

The ink in these Staedler color-pens is more runny than the BIC Cristal pens, so simply holding the tube over a fresh roller lets the ink drip onto the felt. Three new rollers, with each a different color ink:

The ink is still quite slow to soak into the felt. After an hour it is deeper, but by no means uniform. If the soaking has 'halted', as e.g. on the green one, another drop is added.

With the lids on, these were left overnight in their trays to fully soak through the entire roller. The next day the felt is completely colored, with ink distributed throughout; the purple roller was then placed on the machine:

To make sure the felt is properly saturated through and through, the obvious thing to do is to add another drop of ink just to make sure. That works, but probably also leads to an over-inked roller.

When typing with an over-inked roller too much ink is rolled onto the type. This causes excess ink to be flung off the type at impact with the paper. This causes streaking or splatter around the characters - seen on the left-most 'test' typing. The remedy for bad inking caused by too full a supply of ink is rubbing the pad with blotting paper, as advised by a Blickensderfer instruction manual:

Not blotting paper, but a bit of card works just as well - removes excess ink from the surface. 

This does indeed eliminate streaking and splatter - the right-most 'test' typing. The letters are printed clear and reasonably crisp, but noticeably fainter than before.

The typing quality is definitely not on the level of a typebar machine with ribbon inking. On the other hand the typewheel used here is new, made with a 0.08 mm layering. (The Attic typeface used here is also a bit too ornate for typewriters perhaps.) Earlier experimenting with water-based ink and heavy inking gave much better writing, but were impractical because of soaking through the paper and drying out within the day (or hour!). 

Overall the oil-based ink works, but the printing quality is very sensitive to the level of ink on the roller.

Looking closely at an original typewheel's type ('slug'), the top is not sharp as a typebar machine's type, but has a definite flat surface facing the paper. That flat surface is probably by-design. That surface is there to take the ink and act as the stamp. Ribbon-inked machines that work on impact do not need this flat surface, the impact onto the ribbon material presses ink onto the paper.

The needs of the 'stamping' process will be behind the typing advice given in the Blickensderfer instruction manual. On a regular ribbon-inked machine the typing is 'staccato'; the fingers strike the keys to fling the type against the ribbon and paper at speed, to rebound immediately. The inking is done by impact; near-instanteneous. On the Blickensderfer typing should be not by striking the keys, but rather by pressing them down - the type should be pressed against the paper to act as a stamp. This will be needed to give the ink time to transfer onto the paper, as in stamping. It's explained in the manual: the key must be followed down until the type is stopped by the paper.

Even though pens give low-cost oil-based inks (which oil?) and do work, the ink of these particular colored pens is not great - too runny and relatively light on colorant. Current impression is that the BIC Cristal inks are better suited for the Blickensderfer; thicker, sticky and very dense. Also the type itself on newly-made wheels can perhaps be optimised for the printing process. 

Another realisation is that ribbon-inking is a very good, robust solution for typing.

More tinkering (playing) may be possible on getting this Blickensderfer 5 to type as it would have done 120 years ago :-)

Blickensderfer ink idea

An idea: very cheap (or free!) ink that is widely available and ideally suitable for using on a Blickensderfer typewriter.

On this Blickensderfer No. 5, the 'tinkering machine', the platen was replaced with a new one. The paper is modern, sold as suitable for both inkjet and laser printers. For the type, we've a few original wheels and a near endless supply of new typewheels to optimise the type-design. Remains the ink - several were tried and they did work, but none were ideal.

From gun-cleaning felts and a bit of brass tubing, new felt-rollers can be made. A bit of superglue (slightly viscous, not the very runny) to the sides helps give the felt firmness and keep it in its shape. For the inking then, generally a stamping ink is used. Modern stamp inks are usually water-based, although oil-based metal-stamp inks are also available.

Water-based stamp ink does sort-of work on the Blickensderfer, however, the roller dries out very quickly (in a day). And with the level of inking that's needed to get a good imprint there will be bleeding of the ink through the paper. For example; here the reverse of a page with one line written with a water-based ink:

Oil-based inks are thicker and don't bleed through quite as easily.

However, oil-based stamp inks are less easily found and small bottles are surprisingly expensive. Oil-based black ink works on this machine, although still sensitive on inking-levels for the felt. The colored oil-based inks are all too runny with not enough colorant. I.e. the colored inks splatter; lots of small droplets around the typed character.

Thinking about the inking process of the Blickensderfer typewriter, it is perhaps a bit like a miniature paint-roller. Thick 'wall paint' rolled onto the type, before it gets pressed onto the sheet.

Not having the original specification of the Blickensderfer Manufacturing Company for the ink, it probably specified:

• an oil-based ink, 
• very dense in colorant, 
• very thick (high viscosity), much thicker than stamp inks,
• slow to evaporate, slow to migrate in dense felt,
• and probably, ideally a bit sticky.

Then had an idea! Where to find such an ink! This ink is everywhere and cheap too.

Ballpoint pen inks are oil-based, they don't run in water. They are dense in colorants (a very thin layer of it is deposited on the paper), they are highly viscous and a bit sticky too. What is more; ballpoint pen ink is widely available in small quanities for very reasonable prices! (Sometimes free.)

For much less than a Euro purchased a small amount of blue ink from a reputable brand.

The cartridge can be pulled out of the pen easily. Removing the tip from the tube varies per brand, some can be pulled off easily, some require a bit of 'chewing' with pliers before they come off. But then we have a small tube filled with oil-based ink.

This particular cartridge's internal diameter is about 1.8 mm filled with just over 100 mm of ink. I.e. it contains about 250 mm³ or a quarter cc of ink. (Whilst the price for this quarter cc is very ressonable, the price per litre is of course staggering. Fortunately we only need a quarter cc.)

A Blickensderfer ink-roller is about 7 mm diameter with a 2 mm bearing-tube in the centre and 8.5 mm wide, then the total felt volume is about 300 mm³. The amount of ink that can be absorbed into 300 mm³ of felt will be less than that. Ergo, one pen should contain enough ink for one, probably for inking two ink rollers.

Holding the tube vertical over the felt roller, the ink will drop slowly onto the felt.

To pause, place the tube horizontal again, the ink will stay/withdraw into the tube.

The ink very slowly infuses the felt - it will take a day to fully migrate into the roller.

Even with the ink only in the outside of the roller, the ink does stick to the type for printing onto the sheet.

After inking a roller or two, the tip can probably be pushed back onto the tube and fitted into the pen again. Ready for writing, or inking another roller.

More experimenting to be done, but it seems a promising source of ink for the Blickensderfer typewriter! After letting the ink diffuse into the felt for a day, may apply one more drop to it.

Some even cheaper pens or some free advertising pens still to be tried perhaps. (Although the quality control of a reputable brand feels good to have for this; the ink will be better, of consistent quality and be free from harmful components.)

And to experiment with colours! Some brands make these pens in many colours; finally a purple writing Blick, or brown, or ...

An idea!

(So silly not to have thought of this before. Oil-based ink was right there all the time, scattered all around the house!)

Manufacture of platens and Durometer values and Durometer Types

The manufacture of typewriter platens is described in an article in the June 10, 1919 issue of The Rubber Age.

The article is written by and for those deeply familiar with the rubber manufacturing industry, it is filled with jargon and technical terms. Typewriter-related, it explains the function of rubber as the platen material.

A bit further on, after delving into manufacturing, the desired hardnesses of the platens is mentioned too.

The mentioned readings of between 65 and 70 on a durometer are surprising.

When Shore Durometer values for typewriter platens are mentioned today (or yesterday, for that matter), the values are generally in the 87 to 97 range. Those are Shore (A) values, this A is not always added, but to be unambiguous it should be added. There is a wide variety of different Shore scales and the letter is needed to identify on what scale the value should be interpreted, or pur another way; to identify what instrument was used to read the value.

The actual hardness needed in 1919 is surely not different from the hardness needed on a typewriter today; so the article must be meaning different durometer values than the default, usual Type A Durometer.

There are additional hints in early references to Shore Durometers and their use. When introduced in 1915, there is no mention of different scales or types. The dial simply says "Hardness"  without any extra Type indication. The original Durometer is most suitable for soft rubbers, such as for automobile tyres of the period. Very early on however, there are references to a soft rubber durometer and a hard rubber durometer.

Readings with the original tester on hard rubber, i.e. with values over 90, were advised to be unreliable. Another method, or instrument, would be needed to measure hard rubber.  The solution that was taken by Shore was to create a hard rubber tester by changing the flat-tipped indenter-pin of the Durometer for a pointed pin. This sharper, pointed pin was already in production for the Elastometer, so this would have been a simple, obvious step to take that required almost no effort or costs.

In literature into the 1930s there is mention of a Shore soft rubber durometer and a Shore hard rubber durometer, suggesting this is what these types were originally called. This would fit with/explain that the box of this ~1941 Type A Durometer has 'soft rubber' scribbled inside the box lid.

These two types, soft and hard rubber, were (later?) defined as the Type A and the Type B by the company. The Type letters were added to the dials by at least 1930, probably earlier.

The Type A in the picture above would have been called a soft rubber Durometer (or simply Durometer) in 1919. The ~1958 Type B in the picture below would have been called a Shore hard rubber Durometer back then:

The dial on this instrument is marked as Type "B" and it has the sharp, conical pin. The spring and everything else is identical to the original Shore Durometer, i.e. the Shore Type A Durometer.

When making a new platen for the Blickensderfer a while ago, several hardnesses of TPU were tried. The platen made with TPU that was sold as having a hardness of Shore 95 A was experimentally rated as best. With an old sector-type Durometer however, readings below 20 or above 90 are not reliable, so the actual hardness of the finished platen could not be checked.

Testing this newly made platen with a Shore hard rubber durometer, i.e. with a Shore Type B Durometer instrument, it shows a value between 65 and 70! When slowly rolling over the platen (method for testing cylindrical parts), the value reaches close to 70 at its maximum.

The thickness of the rubber on the platen core is about 3mm - a bit too thin for a proper measurement. Nevertheless, this result is good enough to confirm that the durometer values in the 1919 article are indeed meant to be read as Type B, i.e hard rubber durometer values.

Another conclusion from this is that within a few years from the introduction of the Shore Durometer, already a second type of Shore Durometer was introduced. (For such a common and even standardized instrument, not all that much of its history is available - perhaps not surprising, a deeply niche subject :-)

The Shore Type A Durometer is the original instrument of 1915, the Type B is a second, hard rubber instrument that was in use already in 1919.

Remington Portable early model

First new typewriter in a while! Although early Remington Portable typewriters are not particularly rare, they're not too common in Europe. So when the opportunity came along to get one, for a reasonable sum too, sprang for it.

Not sure if these are very 'collectable', but I'd say it's a notable 'milestone' typewriter design. It represents an impressive feat of engineering that -accelerated by well-funded and good marketing- arguably defined the portable typewriter category for decades. (So deemed it worth finding that little bit of extra shelf-space for.)

This is not the very first model of the Portable, this machine NV10943 dates from July 1921 and the outer housing had just switched to flat-bottom with rubber feet instead of the dimples with cotter-pins. This specimen also has the second style of 2-hole type-guide, this update being phased in on-off over the July production (i.e. there are later July 1921 machines that have the early style).

One sign of an early Portable still there: no exposed shift-stop screws, plain side-wall of the outer frame.

On these early Portable machines, the serial number is stamped in the frame part of the machine, instead of in the outer shell - sensible. Also visible is another feature of all #1 Portables, the rear carriage rail is short - maybe even will allow for the bearing-cage to be slid off without completely loosening the rear rail.

Some of the #1 machines seen online are missing one of the 3-hole half-spools; they may actually only be missing the spool flange. This has come unstuck from its core and it's only luck that it is still with the machine.

Even though it already has some of the later features, this machine does still have the curved paper-table and doesn't have any supports.

Unfortunately, the line-spacing sprung roller is missing. Only the base of the spring is still there; broken off. The line-release lever had been replaced with a much later, #2 Portable lever (removed in above picture). This may be the cause of the line-spacing roller breaking, perhaps there are subtle differences in design beyond the length of the lever.

The early lifting-tray slides very smoothly in its guides, no play at all. The mounting to the lifting arms is different from later #1 models. The early mounting has a hex-nut.

For comparison, the #1 from 1924 in below picture has the lever fixed much the same way as the #2 Portable:

This above view of a late #1 also shows how the outer frame now gives access to single screws of the shift-stops. The #2 model also exposes the adjusting screw, so two screws per shift-stop. (Well, one is the baseline stop and the other is the shifted-stop, but let's call them both stop-blocks.) Just visible too is the sloped face of the ribbon-reverse knob -the early Portable has no automatic ribbon reverse (hence 3-hole spools are handy to show the user when it's time to reverse).

The shift-lock key has its own key-lever, entirely separate from the shift-key's lever.

Another quirk is that this machine has a regular, international keyboard with accents. The accent keys are however not dead-keys - typing an accent grave will index the carriage. In practice this won't have been an issue; to type e.g. "é" first press down the spacebar, then type e and then the accent and then let go of the spacebar.

The typewriter was briefly taken of its base to remove some dust.

Surprisingly, whilst the carriage rails are brightly nickeled, the internal mechanism of this specimen is mostly blackened. The bell, spring-drum and most of the rods and spacers are black.

As is to be expected, it shows signs of having been serviced such as that wrong long-lever line-release, and also has several spots where thick black paint was used to re-touch.

This Portable has, of course, a rock-hard platen and no functional line-feed, but other than that it all seems to work. Robust machines :)

Maybe to scout-round for a replacement line-feed roller and a correct pattern release lever,  but first it goes on the storage shelf. Wrapped in plastic to await a later full cleaning and touching-up (and perhaps full repair, new rubber?).

So finally got one! An early Remington Portable, the start of a very long line of robust personal writing machines.

:-)

Snagged one!

 Arrived last weekend - need to take more pictures, but already sneak peek.

More pictures to come -and discovering the state it's in :-D

Fixing-up a Shore hardness tester (Type "T")

When hobbying-around with typewriter platens, it's about rubber and the hardness of that rubber. To give that a number, usually the Shore hardness or Durometer hardness gets mentioned. To be able to measure that myself, tried to get a Durometer - and instead of one of the common, widely available items I tried to get a period-correct specimen to match the pre-war typewriters.

So already a few years ago, I bought a relatively cheap, used Shore Durometer on the local classifieds site. That proved to be a a bad purchase. The listing pictures hadn't shown it, but it was a wreck; missing window, broken pointer and somehow jammed halfway the scale. The dial was so heavily pitted, that it was hard to read anyways. The item was put away on a shelf, written off as a 'fail'.

However, having gained some more confidence and because of the platen-testing with the Blickensderfer, it was taken down again and opened up. Normally wouldn't dare take apart such an instrument, but it was broken anyways so nothing to lose.

Very quickly a new window was cut from some plastic-sheet (packaging) and a thin strip of card added to the curved, shiny distance bracket. This is needed to compensate for the difference in thickness of the plastic sheet with the original glass. With a fine camelhair brush, the black pitting of the dial was retouched with gold watercolour paint.

The spring-assembly was taken out and the small bearing in the lower-left corner that holds the axle of the pointer was screwed-out. That allowed the pinion to slip a tooth with the rack-segment on the horizontal 'weighing-bar' that holds the pin. (No idea how that got out of sync, it must've had quite some mistreatment!)

Re-assembly is -as they say- the reverse of disassembly.

This leaves however the adjustment - this specimen will not ever be a reliable tester again, but wanted to make an attempt to at least get it 'reasonable'. Still more reading-up to do on Durometers (a lot more!), but it boils down to setting/checking pin-exposure, adjusting spring-constant and setting/shifting the force-level.

First-off, the pin should be exposed 0.1" from the base (abutment). This is unlikely to be out of adjustment, but astonishingly this one was. The pin can be screwed in or out and is fixed with a tiny set-screw (orange). Vernier-calipers should be fine for now. Then the spring constant should be adjusted to be about 74 gf per 10 on the scale (that is for medium-spring Durometers - there's a world out there!).

To be able to measure, read the scale and adjust at the same time, a testing stand was made from Meccano. Fortunately the Meccano standard BSW 5/32 thread is a beautiful fit for the threaded hole in the knob of the Durometer - made for it!

To adjust the ratio of pointer-movement per force applied, the link can be moved over the beam. To reduce movement per force, move to right and vice-versa. Fix in place with its screw (green).

Then the absolute level of force for the values has to be set. That can be done by changing the pre-load with the distance-bush. Use small pliers or a tiny wrench to rotate the bush until right (purple).

All this having been done (a couple of times), the Shore Durometer again reads close to 60 when pressed against the check-block that was in the box. There may well be a better way, but so far this seemed the logical order of things. (Maybe the factory adjusting instructions for these instruments will shortly show up online!)

After reading more about Durometers, it's become clear that this set is a hodgepodge - it is wrong. The check-block has serial nuimber 6622 and the instrument is 13764 - the check-block should be with instrument 6622 and 13764 lost its own check-block. The black leather box likewise is wrong for the 1940s crinkle-black instrument, probably it's the box of the 6622 instrument.

Originally I had assumed that the "T" on the dial was some confusing 'freak' corrosion, making it look like Type "T". But this is actually correct! This is really is a Shore Durometer Type "T". It has a spherical presser-pin, the '2-pound' spring and a concave abutment plate - i.e. a Type "T" tester. 

The Type "T" Durometer is probably pretty rare, as it was made for a very specific use-case in one specific industry. (Lucky find.) It is also not at all suitable for assessing the rubber of typewriter platens. (Less lucky.)

Shore Durometers are a whole subject in and of themselves, as I'm discovering - more Durometers to come I'm sure and perhaps an agelist to be compiled too!

(rabbit-hole :-)