the Papertrail – Page 28

Making a Display Matrix, but Which One?

Posted on 2015/06/01 by kpmartin Posted in Kevin, Matrix Making, Matrix Markings — No Comments ↓

It seems natural for me, as a first project using my new pantograph engraver, to try making a matrix. Rather than designing a whole new family of typefaces (or even a single typeface), I decided to make a single character. What people seem to be looking for the most lately is the at-sign @, for use in e-mail addresses.

In the Monotype matrix numbering system, the @ is considered a “Commercial Symbol” and so has markings between 20P and 29P on the “face” section of the marking (located on the front of a cellular matrix). The body size is marked as usual in the “size” section of the marking (located on the side of a cellular matrix), and being a symbol, there is a third designation of 2 because @ is Commercial Symbol number 2 (number 1 is the percent sign) marked on the back of a cellular matrix. These markings are generally augmented with alphabetic codes indicating set-width and unit-width.

For instance my specimen book lists 3 different 10-point @ symbols, coded “2-10Vb 20Po”, “2-10U 20Po”, and “2-10U 25Po”. The ‘20P’ or ‘25P’ indicates a Commercial Symbol, the ‘2’ indicates an @ symbol specifically, and ‘10’ is the body size in points. ‘Vb’ indicates a set-width of 9½ points, while ‘U’ indicates 10 points. Finally the ‘o’ indicates the correct width is 18 units wide (i.e. 18 18^ths of the set-width). In general with symbols there is no correlation between numbering and appearance; in this case the first one is a slightly narrower version of the second one, while the third one has slightly less variation between the thinnest and thickest strokes.

The number of styles available varies with body size. The smallest is “2-4½Y 20Po”, the largest in cellular matrices are “2-12T 20Po”, “2-12S 20Po”, and “2-12S 25Po”. Although other symbols are available as cellular matrices up to 18 points, the @ symbol is not among them. In contrast to the spareness of variety in the @ sign, my specimen book lists 27 different percent signs in 12-point. Many of these have “Symbol” designations like “1-12S 26Po” but some have face-specific designations like “1-12Tb 609Jo” which is a 11½-set (‘Tb’) 18-unit (‘o’) percent sign made to match face 609J (20^th Century Ultrabold). Such markings do not specify that it is a Commercial Symbol, so a pilcrow ¶ (Reference Symbol number 1) specific to the same face would have the same markings if one existed and was the same width.

The @ symbol is also available as display matrices, the smallest being the 14-point “14-21 No.2” in the specimen book. The ‘14’ is the body size, the ‘No.2’ refers to Commercial Symbol number 2, and the ‘21’ seems to refer to the 20P-29P range on cellular mats for Commercial Symbols. Other examples, though, disprove that last statement, such as the dagger “18-25 No.3”; the dagger is Reference Symbol number 3, and so would have a second number in the 40’s (Reference Symbols) rather than the 20’s (Commercial Symbols).

Some other symbol display mats, though, lack the ‘No.n’ designation, and in such cases the second number is the number of the matching text face, so for instance there are percent and pound-sterling signs both marked “24-42” which have an outline style clearly intended to go with text face 42 (DeVinne Outline). In these cases, though, there is nothing identifying the mat as a Commercial Symbol nor naming the specific symbol; you have to recognize it from looking at the actual mat cavity shape, just as you have to distinguish an ‘A’ from a ‘p’.

The largest display @ sign is “36-21 No.2” and there is exactly one of each standard display size. There are no alternates nor any face-specific ones.

So I have set myself a project to make a matrix for casting an @ symbol specifically designed to match a face. The font I have chosen is 18-point number 217, Swing Bold. There are two reasons for this choice: One is that I have recently cast some Swing Bold and have done some close-up study of the letter forms because my mats did not match the sample letters I given to match. The other is that this face is a script style (somewhat, at least) and so the join of the ‘a’ and its enclosing circle flows naturally. The origins of the symbol are not known for certain and there are many theories, but they pretty much all seem to come from informal handwriting rather than calligraphy and thus the flow from the ‘a’ to the circle is natural with script or italic faces. It is much less clear how the ‘a’ and circle should be structured and styled if one wanted to match a roman face or, worse yet, blackletter.

Such a mat would appear to be rightly marked “18-217”.

If this all works out I’ll do it for other sizes, and maybe expand to include ‘/’ and ‘#’ which are also becoming popular. Making them for other faces is a more long-term thing.

From drought to downpour

Posted on 2015/05/31 by kpmartin Posted in Gardening, Kevin, Weather — No Comments ↓

We’ve had several weeks here with essentially no rain, and the garden has been looking rather sad. I planted tomatoes, cucumbers, melons, and basil around May 24th, with promise of rain (finally!) in the forecast but it did not materialize, so I’ve has to hand-water the transplants.

Yesterday the rain came with a vengeance! It rained so hard that there was a big washout in the garden.

The main washout. The land slopes towards the camera. Soil washed out from the upper part of the garden deposited in a delta in the foreground, almost smothering some eggplants.

The main washout. The land slopes towards the camera. Soil washed out from the upper part of the garden along the schoolyard (about 12m away) deposited in a delta in the foreground, almost smothering some eggplants. The darker soil is composted manure which I had spread on the soil and has now been redistributed by the water.

The finer particles that didn’t deposit in the delta continued to the first trench of potatoes, filling the trench with mud. I was going to fill the trench as the plants got bigger, but the weather has done it for me. I might actually have to rescue some of the plants that have been covered.

Water flowing from the schoolyard dug away at this 30cm slope, especially where I had dug up a large weed recently. The cucumbers plants (against the green trellis), melon (center right) and onions (far right) were not really affected, nor were the weeds (left). However, just beyond the lower right of the photo, the flowing water dug away about 5cm of soil, probably taking out some beans I had planted.

Quite a bit of soil also washed onto the lawn at several places along the edge of the garden.

This erosion probably only damaged some planted beans, because it mostly flowed where I had nothing planted. However there are other areas of lesser erosion that might have done in some carrots, beets, and parsnips that haven’t yet sprouted, and I think I lost at least one Brussels Sprout plant. Things are just too muddy to take a closer look yet.

Another 10 to 15mm of rain are expected today, but as a steady rainfall, not all at once like yesterday.

Challenge Guillotine (still) for sale

Posted on 2015/05/30 by kpmartin Posted in Sold — 1 Comment ↓

We still have our Challenge 265 power guillotine for sale.

I’ve removed the VFD and converted the wiring back to plain 208V 3-phase. The problems with the VFD tripping turned out to be due to a defective current sensor in the VFD itself, and the motor was not drawing the current levels mentioned in the previous posting.

We have also reduced the asking price from $825 to $600.

More information on Matrix pneumatic valves

Posted on 2015/05/30 by kpmartin Posted in Caster Computer Control, Equipment Acquisition, Repair, and Maintenance, Kevin — No Comments ↓

This week I was having another look at the pneumatic solenoid valves I want to use to run my Monotype from a computer. I was somewhat disappointed that the valves I had were the Normally Open (N/O) type and designed for higher pressures than I would be using.

While doing some tidying up I noticed that the valves did not all have the same part number on them!

The original valves I tested were BX758DE2A324, rated for 0-8 bar (0-120PSI) and normally-open operation, but the ones I noticed lately were BX758DE1C324, rated for 0-4 bar (0-60PSI) and normally-closed operation. A quick examination of all the valves revealed I had six of each of these, and six BX758XX2A3JJ (0-8 bar N/O but not sure about these other than JJ means special driver electronics are required to control the solenoid power).

I tested one of the newly-found valves and it did indeed seal properly in N/C mode, which is great because this will substantially reduce power consumption and heating of the valves. Unfortunately, despite the lower pressure rating, their flow at 20PSI when open varied between almost none and barely adequate, as it did with the first valve I tested.

I took apart the valve and found, as I expected, that there was more pressure from the spring push rods holding the valves closed. Opening the back of the valve to remove the springs revealed the difference:

These springs are tiny, about 2.7mm (0.106″) diameter. The lower spring is the weak one from the N/O valve. It has many coils and is thus a soft spring, and when installed it is hardly compressed at all, thus generating little force holding the valve closed. The upper spring is the strong one from the N/C valve. It has fewer coils making a stiffer spring, and its longer free length means it is compressed on installation, generating a much stronger force holding the valve shut. The spring push rods are identical in the two valves.

Both springs are made from the same wire. As an experiment I stretched one of the soft springs from the N/O valve and trimmed off the excess turns to make a spring resembling the one from the N/C valve, installed it in the valve and tested it. It gave a good seal when closed.

Thus is appears I have the N/O vs. N/C problem solved. I have six valves manufactured for N/C operation, and six more that I can convert to N/C by altering the springs. Twelve valves are enough to make 3 control units to run 3 casters.

As for the airflow in these valves, I charted the shutter thickness against subjective air flow as I had done with the first valve, and found a similar relationship between the values. One difference is that in the N/C valve, the shutters appear to be about 0.05mm thicker for a given airflow than those in the N/O valve previously tested. This much thickness difference would amount to about two units of airflow difference so on the assumption that the second valve has more space in it allowing good flow with thicker shutters, I’m going to be trying swapping shutters between valves to see how it affects air flow.

So for my attempts to shrink the rubber seals on the shutters, keeping them in boiling water for several hours (the mildest way I could think of to force out absorbed oils) had no effect.

Cleaning up the pantograph

Posted on 2015/05/28 by kpmartin Posted in Equipment Acquisition, Repair, and Maintenance, Gorton 3U Pantograph, Kevin — No Comments ↓

The Gorton 3U pantograph engraver/mill I just bought needed a bit of fixing up. Some of the bearings in the mechanism were loose, things were dry (of oil) and pretty dirty, and there was a drive belt missing.

I have it fixed up now to the point where I should be able to use it.

The belts were the easiest part. The machine uses two belts to drive the spindle. One runs up from the motor, turns 90° to a horizontal plane, and drives an intermediate pulley on a lightweight arm that moves around to follow the spindle. The other runs from this intermediate pulley to the spindle. Both can be shifted to different size pulleys to obtain eight spindle speeds.

I have a used but serviceable spindle belt, but the motor belt was completely missing. Because of the path of the motor belt, it has to be a round belt rather than the more familiar V-belts. The Accessories book calls for a round linen belt ¼×84″ for the motor and another ³/₁₆×52″ round linen belt to run to the spindle. Big surprise (not!), no one makes this type of belt any more. The closest thing you can get now is round polyurethane belting, which is cut and heat-welded to the desired length.

I had a pair of polyurethane belts made and installed them on the engraver. The weight of the motor provides the tension for the first belt, but the motor is pretty heavy so there is supposed to be a counterweight to limit the tension. My counterweight is missing so there was quite a bit of tension on the first belt. The tension on the second belt is provided by an adjustable rod that pushes the intermediate shaft and spindle apart so this is more readily controlled. In any case I fired up the motor and ran the spindle at a both its maximum and minimum speeds (I had lubricated the spindle and intermediate shaft already) and things seemed to run well. The only problem I foresee is that despite the high tension, the motor belt was flapping quite a bit. I don’t want to keep the high tension because it will stretch the belt, but the flapping will only get worse at lower tensions. The original linen belting would have been lighter and less stretchy and so would have flapped less. Eventually I’ll have to rig a counterweight for the motor so I can control the belt tension, and in the meantime I disconnect the belts when not in use so they won’t stretch.

I gave the machine an overall cleaning and lubrication so the pieces that should slide easily once again do so. This included cleaning all the pantograph parts (after disassembly) with a brass brush, leaving them bright and shiny.

The reduction ratio is controlled by sliding pivots along two of the arms of the pantograph. The sliding blocks have two bolts each that pinch the gibs against the bar to lock them at the desired location.

One of the sliding blocks disassembled. Some of the screws and bolts were missing. The upper groups are originals, and the lower groups are replacements.

I was missing four of the screws that hold the gibs in place on the sliding block. These had 8-32 threads but a strange head shape, so I had to take some modern 8-32 flat-head screws and reshape the heads using my lathe. I was also missing one of the four pinch bolts. These have ¼-26 threads, which are not a modern standard North American size, but I found some ¼BSF (a British size) that were 26 threads per inch and so would fit. The head size was not a match tough. For one thing BSF head sizes and SAE (American) head sizes don’t match; not only are they nominally different sizes, but even for heads that are nominally the same, the actual size is different. If I recall correctly, the British use heads of exactly the nominal size and wrenches that are slightly over size, while the American system uses wrenches of the exact size and bolt heads that are slightly under size. In addition to needing a different wrench size, the replacement bolts have thinner heads than the originals, making it easier for a wrench to slip off them.

For the gib screws I used the four originals plus four of my replacements, but for the pinch bolts I used all new ones so I would not need two wrenches to adjust the reduction ratio. Some day I may make proper replacement bolts that better match the originals with their fat heads. While assembling the sliding blocks I found that one of the pinch bolt holes was stripped, which probably explains why the bolt went missing. Yet another thing I may fix some day (probably by making a new gib), but for now I’ll be clamping the sliding block with just one of the gibs.

On test fitting the sliding blocks on their pantograph arms I had problems getting them to slide smoothly. They had some tight spots but these proved to be due to raised burrs on the bar which were removed with an Arkansas stone. Removing the burrs left one bar sliding smoothly but the other was still too tight. I cured this by making some tiny shim washers to insert between the gibs and the main body of the sliding block. This tightness explains some of the dings I could see in the sliding blocks and the pantograph arms from someone using a hammer to “adjust” them—a practice the manual warns against!

The pantograph has six bearings overall: Four form the corners of the parallelogram, one is the pivot on the fixed point attaching one of the parallelogram arms to the machine frame, and the last connects another parallelogram arm to the spindle. In addition to these, there are two pivots (with two bearings each) on the knuckle which supports the spindle and holds it plumb while allowing it free horizontal motion.

One of the knuckle joints was a bit loose; not loose enough to have visible motion, but enough that by pulling up and down on the spindle you could hear and feel a bit of a clunk. These bearings are easy to tighten: per the directions in the manual, you slack off a pinch bolt, tap the end cap for the pivot shaft in a bit, and re-tighten the pinch bolt. The trick is not to loosen the pinch bolt too much or the cap just loosens up again after you tap it in. The manual warns about having them too tight, which will increase the drag on spindle motion and wear the bearings faster.

As for the pantograph bearings, no two are entirely identical. Two of them are very close: They use identical standard ball bearings pressed into the two ends of the link bar (my name) and are held by identical nuts on posts pressed into two other bars, but the posts are different because the bars they are pressed into are not the same thickness. These were rough so I replaced them with new bearings, which are a still readily available metric size (22×7×9mm), surprising for a machine made in the USA in the early 1940’s.

The other four bearings use loose ⅛″ balls in two rows, trapped between the mushroom end of a stud, a double-sided cup pressed into one of the parts, and a cone loosely pressed onto the stud. All four cups are identical, as are three of the cones, but the studs are all different. One stud is larger and this bearing thus uses one extra ball under the stud head. Three of the studs are held into their mating part using nuts, but one uses a setscrew that grips a flat on the side of the stud shank (the flat is tapered so the stud cannot work out and loosen the bearing).

It took me a few tries to get these bearings reassembled. The biggest problem was keeping the balls in place while the cone was put back onto the shank of the stud. I don’t have an arbor press handy so I did this by tapping them together with a hammer, using various socket wrenches as drivers. I eventually found an order of assembly and an appropriate amount of grease to use to keep everything in place.

Eighteen balls on the cone side of the cup, held in place by some grease

The cone covering the balls, also with enough grease to hold it in place even when upside-down.

The stud with eleven balls stuck to its head with more grease. One of the studs is a larger diameter and takes twelve balls.

The bearing fully assembled. This particular one bolts into a sleeve which is held to the spindle by a pinch bolt. This allow some vertical adjustment so the pantograph is not pulled out of its plane of motion.

Both sliding blocks ready to install, including new felt washers to keep dirt out of the grease.

The two bearings whose cups were pressed into arms of the pantograph required a bit of a balancing act to assemble.

Once the pantograph is reassembled and installed on the machine, the open bearings can be tightened by tightening the nuts on the ends of their studs. Except of course for the bearing that uses a setscrew to hold the stud to the other arm. For this one you have to use a C-clamp to press the stud tight, then re-tighten the setscrew. If you set a bearing too tight, you have to loosen the nut, tap a wedge (a slot screwdriver will do) between the arms to loosen the bearing again, and try tightening the nut again, just right so there is no play, but also as little drag as possible.

More Equipment!

Posted on 2015/05/20 by kpmartin Posted in Equipment Acquisition, Repair, and Maintenance, Gorton 3U Pantograph, Kevin, Other people — 1 Comment ↓

The main reason for my visit to Don Black last Friday was to pick up a new (to me) machine.

This is a Gorton 3U pantograph mill/engraver, which turned up when Don and Craig were reorganizing their stock. This machine is used to perform engraving and 2-dimensional milling following a template, and is capable of enlarging (by about 25%) or reducing (all the way down to 0%) the template image in the process.

There is a table (on the left) with 3-axis motion calibrated to 0.001″ for holding the work being cut. Above that is the engraving spindle itself which is supported by a jointed set of arms which maintain a constant height and keep the spindle vertical. There is also an arm and pulley system hidden at the back which drives the spindle from the motor just visible behind the foot of the machine. By switching the belts to different pulleys the spindle can be adjusted to eight speeds over a range from 3800 to 15,000 RPM.

The pantograph proper is a parallelogram of four arms, with pivots hanging it from the overarm (grey column near top center) and attaching it to the spindle. The enlargement or reduction is controlled by setting exactly where these two pivots are clamped to the parallelogram arms. As the tracer at the end of the long arm (top right) is moved over the template (placed on the upper ridged platform), the spindle moves in a scaled motion to match.

This machine had been sitting in Don’s warehouse long enough that neither Don nor Craig remember where they got it, so it is quite dusty. Some of the bearings in the pantograph joints need a bit of TLC, and one of the drive belts is completely missing, so a bit of work will be needed to get this into running order.

Although Don didn’t have any documents to go with this machine, we’re fortunate enough that Richard Gorton, great-grandson of George Gorton II, has scanned and posted online all the documents he could get his hands on, along with some history of the company. On this site I have found a full set of manuals for this machine, although as with most machine tools the manuals cover the features specific to the machine as the user is expected to understand machining in general on their own.

I plan on using it to cut matrices for my type caster. You can see a similar machine (but I believe it to be a Deckel rather than a Gorton) being used for making matrices by the late Jim Rimmer in the film “Making Faces“

Tagged with: Don Black, Making Faces

Monomatic Parts

Posted on 2015/05/17 by kpmartin Posted in Equipment Acquisition, Repair, and Maintenance, Kevin, Mystery Parts, Other people — No Comments ↓

I got a big lot of what appeared to be justification wedges for a Monotype composition caster from Don Black last week, many of them brand new, still in the protective plastic dip from the factory.

It turns out, however, that these don’t fit the comp caster. The part numbers on them are 310D and 311D rather than 10D and 11D one would expect, and they have too many notches on them for the comp caster. It turns out they are justification wedges for the Monomatic II, a machine produced to supersede the comp caster but arriving in the market too late, when hot metal was on the wane. It appears that the Monomatic’s main improvement was to replace the original paper ribbon encoding with separate encodings for the letter width and for the matcase position thus eliminating any width limitations of the original comp caster. The Monomatic could cast any matcase position to any width, so the letters were not restricted to the (up to) 15 different widths encoded in the Normal Wedge, nor would a letter width have to be fudged because the matcase row for its desired width was already full. The matcase was also enlarged to 18×18 so it could hold 324 matrices, up from the 255 of the 15×17 extended matcase or 272 of the 16×17 unit-shift matcase on the comp caster. That’s enough for two more alphabets.

Not all those wedges are Monomatic II, though. Four of them have only ten notches on them, and are marked 210S1, 211S1, A10D1, and A11D2. These ones are still a mystery.

There were also three other wedges in the lot, but they aren’t justification wedges:

These have a slot cut through then, so perhaps they fit over a bolt to accomplish some adjustment. One of them is engraved “18 pt Nº177” and all three have a scale from 3 down to zero and back up to 3 again.

I also have other parts that are for the Monomatic: some racks that clearly have too many positions for the comp caster (and one of which has a part symbol of 312C18 written on it identifying it as a Monomatic II part), and two bridge carrying frames and sliding frames made for the larger matcases.

Various racks from my parts stash. Front pin block racks on the left, rear pin block racks on the right. The ones near the top are for various Comp casters, but the ones at the bottom appear to be for the Monomatic II.

I have no reason to keep these Monomatic parts so if you own a Monomatic and want them, feel free to ask (all, what, 3 of you?)!

Tagged with: Don Black

Strip Moulds at Don Black’s

Posted on 2015/05/15 by kpmartin Posted in Equipment Acquisition, Repair, and Maintenance, Mystery Parts, Other people — 2 Comments ↓

While I was at Don Black’s today, Don mentioned that in the process of cleaning up their warehouse (a daunting project which appears to be coming along well) he found a few boxes of what he thought were Monotype parts. One box, which I purchased, contained justification wedges (although they turned out not to be for the Composition caster).

There were also three boxes of what were obviously moulds for making rule or leading seemingly made by Monotype but also clearly not for the Composition caster.

My guess is that they fit the Giant Caster, but some expert on this machine would have to verify that. I think I have a manual for this machine somewhere so I might be able to check this myself.

The part and serial numbers (1½ NR2F903H #114). The 1½ is probably the width in points and the ‘F’ might mean full-face rule. Other moulds had a number instead of the ‘F’.

Don has 20 or 30 of these moulds, in sizes that appear to range from 12 point down to ½ point (try pulling that with an Elrod!). There are also several metal plates, in two sizes, with four large holes in each, perhaps some kind of spacer.

So if any of you know what these are (or even better, you want to rescue them), speak up!

Tagged with: Don Black

Cleaning up unearths a treasure—a month late

Posted on 2015/05/15 by kpmartin Posted in Equipment Acquisition, Repair, and Maintenance, Kevin, Monotype Composition Caster — No Comments ↓

I did a round of cleaning up in the shop, partly to search for my missing mat holder, and partly because I picked up more parts from Don Black.

While cleaning up, I found the box of stuff I picked up at Firefly Press after last year’s ATF conference, and at the bottom of the box, mixed in with a pile of matcase parts, were six mould blade kits for American display moulds.

There is one kit for each size: 12, 14, 18, 24, 30, and 36 point. They are fitted for specific moulds and marked with the corresponding moulds’ serial numbers. Needless to say I don’t own any of the matching moulds, but the spacer (“Point Block”) in each of these kits can be used in any mould as they are not serial-number specific.

Had I found these a couple of months ago, I could have avoided going through the trouble of making my own Point Block for running my display mould at 18 points! Now that I have these, though, I can measure the point blocks and add the measurements to my analysis of the relationship between their nominal size and actual thickness. Although they are marked by serial number as well, I may be able to use the Mould-Blade Shield and Mould-Blade Top Guide (what I’ve been calling the Back and Front Covers) to replace missing or broken ones in the kits fitted to moulds I actually own.

Measuring air valve spring strength

Posted on 2015/05/10 by kpmartin Posted in Caster Computer Control, Equipment Acquisition, Repair, and Maintenance, Kevin — No Comments ↓

In addition to poor flow when open, the other shortcoming of my stock of surplus Matrix pneumatic valves is poor sealing (leakage) when operated in NC mode, where the shutter spring is the only force holding back the flow of air.

The port the shutter seals against is about 0.050″ diameter (based on trying various size drill shanks in the port), so its area is .00196 in² and the force against the shutter when the supply is 20PSI would be about 17.9g. Yes, I realize this is cheating, grams are a unit of mass, not force, but I am referring to weight-equivalent force. In CGS units this would be about 17,500 dynes or in MKS units 0.175N (Newtons).

I set up a rather makeshift rig to test the spring strength. The solenoid body with attached rear cover are taped to the arm of a machinist’s height gauge, with the projecting spring push rods just above the pan of a sensitive scale (0-50g×0.01). By lowering the height gauge, the springs are compressed and I can plot the force/distance relationship for all 8 springs working in parallel.

The result was that the individual springs produce 10.5g/mm, that is, for every mm of compression, they produce 10.5g of additional force.

For the spring to generate enough force to hold the shutter against 20PSI it would have to be compressed by about 1.7mm from its free length. However, based on the cross-sectional drawing from the specifications (assuming that it dimensionally trustworthy) the springs are only compressed about 0.4mm when the shutter is closed. Even with the swollen shutters in my valves, the closed compression is only 0.9mm. In fact the fully-compressed length of the spring is only 4mm less that its free length, so the most force the spring could ever produce is about 42g, enough to hold back about 45PSI.

Clearly, the valves actually designed for NC use have stronger springs in them so they can hold back the rated pressure of 8 bar (120PSI). This is hinted at by the cross-section which shows a spring with heavier wire and only half as many coils as the springs in my valve, although comparing the springs for the compressed and relaxed position in the cross-section show a different coil count, so the spring drawn there may just be a schematic representation.

The Monotype caster only needs about 20PSI to operate it, so rather than using stronger springs, I could make 2mm spacers to insert between the springs and their push rods. This would be enough to seal against about 28PSI, more than enough to run the caster.

Another possibility is to stretch the regular springs by about 2mm, but I would rather avoid making irreversible changes to parts of the valves. This would, however, be much faster than making tiny spacers.

I can also run the valves unmodified in NO mode, where the solenoid supplies the force to resist the air pressure. This just involves a slightly different design for the manifold that supplies the valves, a software change to invert “on” and “off” and more heat generation in the valves because they would spend most of their time energized.