the Papertrail – Page 30

Yesterday’s dumb move

Posted on 2015/04/06 by kpmartin Posted in Font Casting, Kevin, Monotype Composition Caster — No Comments ↓

In my last post I mentioned problems with flash and squirts around the seal between the matrix and the display mould. I have since added a comment alluding to the probable cause of this problem: Forgetting to reinstall the link pin (a3A, between the Connecting Link 2A1 and the centering pin arm) after installing the bridge. The American bridge includes an extra linkage (30A) whose purpose is to raise the centering pin to ensure it clears the matcase between casts. A side effect of this linkage is that everything appears to move about right even without the lifting linkage attached.

Despite the carrying frame having its own lifter springs, this pin and link actively both raise and lower the carrying frame (and with it, the matholder or matcase). When the centering pin arm is down (for casting) this link pushes the carrying frame down until it hits its stops, at which point a spring inside the Bridge Lever (b2A) compresses to take up any further downward motion of the link and lever. When the centering pin arm is up the carrying frame is raised most of the way by its own lifting springs but as these springs extend they weaken, and before the carrying frame is all the way up (about 1/8″ short of its upper stop) downward force from the centering spring pin (through the lifting mechanism mentioned above) balances this and the remaining lifting must be done by the link.

With the link disconnected, the carrying frame does not rise as much as it normally would, nor does the centering pin. At the down position, the carrying frame is held down by the centering pin pushing the matrix holder down, which pulls the carrying frame with it. The force of the centering pin is thus substantially weakened because of the countering pull of the carrying frame lifting springs and so there is almost no net force pressing the mat onto the mould. Thus at even the weakest pump spring setting the molten metal was able to lift the mat enough to leak by.

So how did I notice I had forgotten this pin? When I was first casting I noticed something a bit odd: On each casting cycle, just as the matholder finished rising, it shifted to the right a bit, maybe 0.1 or 0.2″ (and returning to the proper position when the matrix jaw closed again) but by holding the handle of the matholder, I could keep it in its proper position with little effort. I thought nothing more of it until I started shimming the mat and noticed that this sideways shift had increased. By then I was done casting, but I took a look between the matholder and mould while cycling the caster manually. The matholder was being shifted because the end of the type carrier was rubbing against it, in fact, rubbing against the mat itself (very close to the bottom edge, where blemishes don’t matter). When I shimmed the mat, the angled path of the type carrier encountered the mat a little sooner so it shifted further. I knew the carrying frame should be lifting higher at which point the light came on and I realized I had forgotten the linkage pin. It did not occur to me until this morning that this might also explain the squirts, though.

Today I did casting with the linkage pin and no shims on the mats and everything worked fine, no flash and no squirts.

However, my questions about the sensitivity of the carrying frame adjustment for display casting are still unanswered.

But the type still seemed to have big feet so I did a few other odd jobs. One was to cast actual samples of the worn “Styles” which I showed as a mockup made from scanned text when discussing the narrow-cast types I had to copy. I also wanted to switch from Linotype alloy to a harder Monotype alloy for the final casting, so I removed the pump and drained the pot on my caster. In order try to fix the big feet problem I disassembled the display mould again and I will clean and reassemble it again in a few days. Finally, I did a trial fit of a lead-and-rule mould on the caster to see what it involved. Based on the instructions this is indeed very involved and I wanted to see why so much apparently unrelated stuff had to be removed to fit the lead-and-rule attachment.

Making a US Display Mould Spacer—Finishing and Testing

Posted on 2015/04/06 by kpmartin Posted in Equipment Acquisition, Repair, and Maintenance, Kevin, Monotype Composition Caster — 1 Comment ↓

I became so involved in finishing the 18 point display mould spacer that I never took any pictures of the process.

Using a flat file, three diamond sharpening “stones” and a wood block coated with polishing compound, I finished the spacer to a thickness of 0.2503″ leaving a little over the target size of 0.25015″ to allow for final adjustment after trying it out. The sharpening stones were ones purchased from Lee Valley years ago (similar to but larger than item A in their current listings), and I used paint thinner as a lubricant on them. This has a low viscosity so it carries the swarf away well, and leaves no residue after wiping it up. Wiping the stone with a paper towel removed both the thinner and swarf leaving a clean stone.

I started by finishing one side, which I got to a mirror finish (albeit with small scratches) using the polishing compound. Then I worked on the other side, monitoring the reduction in thickness and especially looking for uneven grinding causing the faces to go out of parallel. After a while I got a feel for how much metal each stone would remove with some particular number of strokes so that made it easy to control the grinding process.

I reassembled the mould with the new spacer along with the rest of the 18-point blade kit (which is also missing the rear blade cover but this is a less critical part if the mould is handled carefully), and installed it on the caster as part of converting it over for display casting.

Other than being a bit rusty on the display switchover, the first problem I had was lack of cooling water flow through the mould. I had to remove the mould from the caster and use the special coolant passage flushing tool to open up the flow. After that there was at least enough water flow for testing, though not necessarily enough for casting large amounts of 36-point type.

Test casts revealed that the size is very close to correct, but I was also getting “big feet” wherein the size of the type was larger at the foot than at the head. Trying to lock such type into a chase would result in a forme bowed inward. In small measure this is actually good because it prevents work-ups and installing the chase onto the press bed usually flattens everything out, but in extreme cases this can destabilize the lockup and let the entire forme fall out of the chase when it is being moved.

One possible cause of big feet is dirt caught between some of the surfaces when the mould is assembled. This is one of the disadvantages of the American display mould design compared to the English: changing the type size requires fiddling with precision mating surfaces.

Until I resolve the big feet problem the verdict on the spacer is too close to call.

Other casting problems I ran into were a slipping drive clutch and heavy flash sometimes blossoming to a full squirt where the mat meets the mould.

My caster is driven using the system that uses a Rockford clutch, for which I now have some documentation. This clutch is intended to run dry, but mine has been contaminated with oil from the gears it drives. The book states that to avoid getting oil contamination on the clutch, the gears should not be oiled. Now I know, and now I have to tear down the drive system and clean off all the oil. Most of the sliding surfaces in this drive have Oilite (porous brass) bearings which act as a sponge to hold enough oil to lubricate the bearing without dripping any excess. On the other hand, it irks me to have completely unlubricated gearing, so when I clean everything off I may use some sort of solid lubricant on some of the surfaces, perhaps spray-on teflon or paste floor wax, which will stay where I put it.

When I was casting I found that a lot of metal was leaking where the mat presses against the mould face. This produced either heavy flash around the head of the type, or a squirt that required stopping and cleaning the caster. I reduced the pump pressure to a minimum to see if the problem was weak pressure on the mat but this made no difference. The next suspect was a misadjusted bridge, where the carrying frame did not go far enough down and held the mat hovering over the mould rather than pressed against it. Rather than fooling with the carrying frame adjustment and possibly buggering up what might still be a correct setting, I put a few layers of thick paper behind the matrix in its holder, which also has the effect of lowering the mat a bit, and behold! The squirting stopped and there was only a tiny amount of flash on the type.

The adjustment for the carrying frame height has two different procedures in two different manuals. Casting Machine Adjustments in its various editions uses a special adjusting tool. You remove the mould and matcase/matholder and slide the tool into the sliding frame where the matcase normally goes. You then use feeler gauges between the tool and the caster table to adjust the carrying frame to the correct height in its lowered position. Alternatively, page 39 of The ‘Monotype’ Casting Machine Manual provides a more down-to-earth method. With a composition mould and a case of composition mats you adjust the carrying frame height so that two layers of keyboard ribbon placed between the mould and matcase will pull out easily, but three layers will be trapped. This represents a clearance of 0.006-0.009″ which means that composition mats will be touching (with their own weight) but not pressed against the mould when the frame is down. Composition mats have some freedom of movement in the matcase, which means there is such a sweet spot for carrying frame height where the frame is neither lifting the mats off the mould nor pressing them down. The lack of pressure means the mould blade can still move to adjust the set width without rubbing hard against the mat.

It is not clear to me if any such play exists in the display mat holders, though, even though the mould blade still needs to move once the carrying frame descends. Without such play, the carrying frame height adjustment would have to be made to a very high precision. The only places such play could exist would be where the mat holder slides into the sliding frame, and where the mat itself is held in the holder. The American mat holder actually has a separate plunger that transmits the force from the centering pin to the rear of the mat, so enough centering pin pressure could in theory push the mat a bit out of its holder to contact the mould but that doesn’t really seem like a reasonable system to me. The centering spring would have to overcome the pressure from the clamps on the beveled mat corners, and the constant sliding would cause wear to the corners of the mats. Furthermore, neither the English display mat holders (for either American or English mats) nor an older (pre-X41A) American display mat holder design have any such provision. I suspect the plunger is only there to provide a suitable metal for catching the tip of the centering pin. I have yet to investigate the alternative, that the mat holder can move vertically in the sliding frame.

Making a US Display Mould Spacer—Roughing

Posted on 2015/04/03 by kpmartin Posted in Composition Caster, Equipment Acquisition, Repair, and Maintenance, Kevin, Monotype Composition Caster — No Comments ↓

I’ve started making an 18-point spacer for one of my US Monotype display moulds per the drawing in my last post.

The material I started with was ⅜×¾″ hot-rolled steel because I had a piece handy. The bar was about 8″ long so I started by milling off the two sides to narrow it down to ⅜×½″. This will give me spare stock in case I want to make others. This stock will work for up to 24-point spacers.

Stock milled to ⅜×½″. Top and bottom surfaces still have mill scale.

Stock milled to ⅜×½″. Top and bottom surfaces still have black mill scale on them.

I clamped the stock in my milling vise with one end extending about 1⅜″ and started by drilling the hole right along the center line, a little over ⅝″ from the end. Once this was drilled, I used its location as the origin for CNC milling the outline of the spacer using 3/8″ endmills (first a roughing mill, then a regular one for removing the last 0.005″).

The hole has been drilled and the mill origin will be set to this location.

Using a ⅜″ roughing mill to remove most of the excess metal.

A regular (finishing) ⅜″ endmill is cutting the final pass of the outside contour. This "final" pass was run a second time offset a bit because the mill turned out to be slightly under its nominal diameter, leaving the part too wide.

A regular ⅜″ endmill is cutting the final pass of the outside contour. This “final” pass was run a second time offset a bit because the mill turned out to be slightly under its nominal diameter, leaving the part too wide.

This gave most of the ‘d’-shaped outline of the spacer. The remaining end will be shaped once the spacer is cut from the stock, but for now the stock makes a good handle for securing the work.

The next step was to surface-mill the top and bottom of the part to reduce the metal from ⅜″ down to somewhat more than the 0.2501″ target thickness. Any remaining metal removal would be done by hand using a file or diamond grinding stones. Rolled steel commonly has locked-in stress in its surface layers, so this thinning was done 0.010″ at a time, flipping the part over for each pass so the removal was symmetric to avoid warping.

Surface milling the part to get it near the correct thickness.

I was not sure how much metal I would have to leave for surface finishing. My mill is a bit out of tram (the spindle is a tiny amount off vertical) so the successive passes of the endmill leave a very slight sawtooth shape (which I found on measuring to be less than 0.001″ deep). Despite placing an adjustable parallel under the bar before clamping it in the vise each time, it is also apparently a little off level because the metal is about 0.003″ thicker near the stock compared to near the tip.

Uneven milled surface. The wide smooth area farthest from the end was caused when the endmill took a slightly heavier bite and the vibration and downward pull (from the spiral shape of the cutter) draw the milling head down to the lower limit of its backlash. The other stripes are due to the mill being out of tram.

I also ran into problems with the Z-axis backlash on my mill, which is around 0.008″. The weight of the mill head is imbalanced so it does not drop under its own weight to take up the backlash; when moving down, the leadscrew is actually pushing the head down. Once you start cutting, though, forces on the tool can be enough to pull the head down, at which point it suddenly starts cutting 0.008″ deeper. This happened on the last cut just before the photo above was taken. I had to modify the GCode file to lower the head too far (beside the part) and raise it up again to the desired depth in order to get consistent cutting depth.

I am using a new (to me) software tool (CamBam) to convert my part drawing to GCode and I’m still not entirely familiar with this program. I did not see any feature for surface milling a raised surface, so I told it to mill a pocket instead as this would also produce the movements required for surface milling. Before doing this I had to enlarge the apparent size of the part so the milling passes would start and end completely beyond the edges.

Removing 0.010″ using a hand file looks like it should be easy enough to do, so I plan to stop the machine work at a thickness of around 0.260″.

Once I had reached about the right thickness, I used a hacksaw to separate the part from the stock. I finished the cut end with a few passes sidecutting with the endmill, and used a file to round the corners. As a result, the outline of this part differs from the drawing insofar as these two corners are not necessarily 1/16″ radius. Also, because the cutting was done with a ⅜″ endmill, the radius of the inside corner by the sloped side is larger than 1/16″.

I filed the milling marks off both faces and ground them a bit to get some idea of the metal removal rates of my three diamond grinding “stones”, and the thickness now reads 0.2627″ so I have about 0.0125″ to remove.

The spacer separated from the stock and with its faces polished up a bit to remove the milling marks

I’ll cover getting it to its target thickness in another post.

US Display Mould Spacer Dimensions

Posted on 2015/03/31 by kpmartin Posted in Composition Caster, Equipment Acquisition, Repair, and Maintenance, Kevin, Monotype Composition Caster — No Comments ↓

I’ve measured all the spacers I have for US Monotype Display mould blade kits. There are two styles (long and short) which correspond to the style of blade front (thin or thick respectively). This drawing shows both superimposed:

There seemed to be quite a bit of variation between spacers, so I chose to set many of the dimensions to round fractions of an inch, to place the hole exactly on the vertical midpoint, and to have 1/16″ radius on all corners. I couldn’t quite justify making the height ⅜″ though.

As to the thickness of the spacers, I measured each one by comparing with standard gauge blocks and charted actual thicknesses against nominal pointsize. Once the gunk of ages was cleaned off, the spacers appeared to have flat and parallel faces to better than a ten-thousandth of an inch. I calculated a linear fit between the nominal point sizes and measured thicknesses, except two of the 14-point spacers that seemed to be at least a thousandth of an inch too thin which were not includes in the fit. The formula I came up with was:

Thickness (inches) = 0.0138887 × Pointsize + 0.0001602

The formula results matched the actual thicknesses of the spacers within three ten-thousandths of an inch. These constants can be justified: 0.0138885 is 0.4% larger than the actual size of a point, and this gives an allowance for shrinkage of the type as it cools from solidification temperature to room temperature. The 0.0001602 provides compensation for the thickness of the oil film lining the mould cavity (which does not vary with point size). That’s my story and I’m sticking to it.

All the blades appear to be about half a thousandth of an inch narrower than the corresponding spacer thicknesses. This allows enough clearance for the blade to move smoothly in the assembled mould.

My partial 18-point kit has a thin-front blade so I will be making a long spacer for it, and the thickness according to the formula should be 0.25015″ but I’ll probably make it a shade thicker and try it out. The size of the cast type is after all the true proof of the spacer thickness. I have never made a part to that accuracy before, and I don’t have a good feel for how much metal can be removed by various lapping and polishing steps.

Endbands (Headbands)

Posted on 2015/03/29 by kpmartin Posted in Kevin, Things we sell — No Comments ↓

I just added a new Page to the static content of our site showing samples of the endbands (headbands) that we sell.

Measuring US Display Mould Spacers

Posted on 2015/03/22 by kpmartin Posted in Equipment Acquisition, Repair, and Maintenance, Kevin, Monotype Composition Caster — No Comments ↓

In order to make an 18 point spacer for use in a US Monotype Display Mould, I first have to determine the dimensions required. I set up a spreadsheet for recording the data and measured the dimensions of all the spacers I had.

Measuring the spacers with micrometers and entering the measurements into Excel

My first observation is that, except for the thickness, there is a lot of variation in the dimensions, with differences of up to 0.010″ from one spacer to the next. This will mean making a replacement spacer should be relatively easy in terms of machining the outline of the part.

My other observation is that there seem to be two styles of blade and correspondingly two sizes of spacers:

On the left the blade has a thick end, about ⁵/₁₆″, and the spacer is about 7⅞″ long. On the right, the blade has a thinner end, about ³/₁₆″, and the spacer (not shown) is 1¹/₁₆″ long with most of the extra length to the left of the hole. In addition to determining the space between the two type blocks, the spacer also acts as a stop limiting how far the blade can open. Installed and properly adjusted in the caster, this stop is never used (the sizing mechanism limits the mould blade opening), but when the mould is out of the caster, this spacer holds the blade from coming out completely. Ideally, the blade should not be able to pull out enough to disengage the nick wire in the left type block from the nick machined in the side of the blade. If the blade comes out further than this, there is the possibility of damage when closing the blade again if the nick wire improperly reengages with the blade nick. The only thing holding the nick aligned is the front blade cover (shoe).

If a short spacer is used with a thick-end blade, or a long spacer with a thin-end blade, this stop seems to work properly, keeping the nick engaged. But as I mentioned in my previous post about blade kits, the spacers are not serial numbered and can become interchanged between kits, leading to the inappropriate use of a short spacer with a thin-front blade. Several of my blade kits are like this. Conversely, a long spacer combined with a thick-end blade will limit the blade opening; this is unlikely to be a problem for small sizes, but 36-point display type requires the mould blade to open to 48 points, and the long spacer might prevent this.

Note also the rough finish to the opening in the blade, again indicating that high precision machining of the spacer is unnecessary.

The thickness of the spacer, on the other hand, is very important, as it determines the body size of the type. The spacer holds the left and right type blocks apart during mould assembly, but once everything is together and both type blocks have been tightened down, the spacer really only acts as a blade stop. I measured the thickness of all the spacers I had and correlated this to their nominal size, and found that they are about 0.36% thicker than their nominal size. This is to allow for the shrinkage of the type as it cools from the type metal’s solidification temperature to room temperature. The thickness measurements were done with a micrometer, which measures to 0.0001″ (a little better than 1/100 of a point), but I found that the thickness of individual spacers varied by up to ±0.0003″ from the exact 0.36% oversize. This variation did not correspond in any way with the serial number of the mould, but as I mentioned, the spacers can be interchanged between kits.

Just in case this represents measurement error, I will re-measure the thicknesses by comparing each spacer thickness against a set of gauge blocks. This will be done using the following setup, with which I was checking the thickness consistency and parallelism of the spacers:

The dial indicator is clamped to the head of a height gauge, and the latter is adjusted to a height that gives a non-zero reading on the indicator and then locked so it does not shift. Everything is set on a granite surface plate. This does not give an actual thickness measurement, but by sliding the spacer around under the tip of the indicator, I can see how much the thickness varies. The small graduations on the indicator are 0.0001″ and in this case the thickness varied by a bit less that that. By replacing the spacer with gauge blocks, I can obtain an exact (as exact as the tolerance of the blocks) thickness.

I also still have to measure the hole size and position. One other observation to simplify my machining work is that this spacer does not rub on anything nor is it subjected to any impact or localized pressure. As a result it does not have to be hardened so I can make my new spacer from low-carbon steel, which will be easier to machine than a hardenable grade of tool steel.

Up, Down, What’s the difference?

Posted on 2015/03/19 by kpmartin Posted in Font Casting, Kevin, Monotype Composition Caster — No Comments ↓

My recent post about setting up to cast 18 point display type got up and down mixed up. When casting 18 point on an English mould with an American display mat holder, the mat must be lowered, not raised as I had stated. There is a mat holder insert kit to accomplish this, but it is the one insert kit that I don’t have.

I have added corrections and an addendum to the original post explaining the oopsie.

Bald eagle sighting near Kitchener?

Posted on 2015/03/19 by kpmartin Posted in Fauna, Kevin — No Comments ↓

On Tuesday I was driving along highway 401 where it crosses the Grand river in south Kitchener when I saw the silhouette of a very large bird flying south of the highway.

I only saw it for a second or two before the view was cut off by the top of the windshield (and besides, I was driving), and saw it mostly in silhouette against dark clouds. Just before it slipped out of sight, though, I saw that it had a white head.

So I’m pretty sure it was a bald eagle, the first time I’ve seen one not in captivity. I was mildly surprised to see one so close to the city, but there have been other sightings elsewhere along the Grand river in the Kitchener area.

Glycerin Specific Gravity

Posted on 2015/03/16 by kpmartin Posted in Composition ink rollers, Kevin, Testing Equipment — No Comments ↓

Today I used my pycnometer and precision scale to measure the specific gravity of the glycerin which we sell and which I use when I’m trying out recipes for home-made composition rollers.

I started taking a video of this procedure but my camera battery ran out of juice before I was done, and the spare batteries were hiding in some Wii controllers and also pretty much drained. I didn’t want to wash up the equipment and restart another day, and I didn’t want to leave everything out either, so I will have an incomplete video of the process posted later. It turns out that you can only watch someone filling a pycnometer, drying its outside, and weighing it two or three times before it gets tiresome anyway.

The only thing missing from the video is the extra step, when filling the pycnometer with glycerin, of rinsing the overflow off the outside of the bottle before trying to wipe it dry. This ensures there is no film of glycerin on the outside of the bottle adding to its weight.

In any case, the pycnometer held 9.934g of water or 12.505g of glycerin (these are weights, not mass, because there has been no compensation for the buoyancy from the atmosphere), yielding an apparent specific gravity of 1.2588 for the glycerin. Interpolating into a table of apparent specific gravities of water/glycerin mixtures gives the value of 98.1% glycerin, and 1.9% water by weight. Contrary to what I had previously stated, the glycerin bottle does state that it is 99.7% pure. We’ve had this bottle for a while, and it is now only half full, so some water has been absorbed from the air over the years, explaining why I found more than 0.3% water. Further evidence of this is that the bottle was slightly collapsed from the water being drawn out of the air in the bottle.

18 Point Frustration

Posted on 2015/03/16 by kpmartin Posted in Equipment Acquisition, Repair, and Maintenance, Font Casting, Kevin, Monotype Composition Caster — 1 Comment ↓

I have some display casting to do in 18 point on my Monotype Composition Caster, but I’m having a tough time finding a set of accessories that will work together to accomplish this.

My original intent was to use my 18 point display mould made by Monotype Corp. in England, and my display matrix holder for using English display moulds with American-style display matrices (part code 49A). This was my preferred route because this mould is in excellent condition. But, try as I might, I’m utterly unable to find this mat holder amongst my casting equipment.

Have you seen this mat holder?

Failing that approach, one alternative would be to use my American-made display mat holder with the English mould. The problem here is that for all display sizes other than 12 and 36 point, the position of the mould cavity is different on American and English display moulds. In particular, for 18 point, the English mould cavity is 3 points ~~higher~~ lower (in terms of matrix orientation) than the American mould cavity. The American mat holder has 4 sets of interchangeable inserts to modify matrix alignment, but none of these is designed to raise the mat—they all lower the mat (typically for casting all caps on a size body smaller that the face’s size) by varying amounts.

American mat holder insert sets. This is not a full selection of all 4 as there is one duplicate here.

American mat holder insert sets. This is not a full selection of all 4 sets as there is one duplicate here.

It is plausible that I might be able to modify one of these sets to raise the mat by 3 points (or, to match the motif of the genuine sets, 0.050″, about 3.6 points), but one piece, in the upper left of each set in the photo, would have to be made longer so I might have to make this from scratch. This is not something I would look forward to because this part has a fairly complex shape. Maybe the lugs underneath can be trimmed to the same effect, maybe not. But that’s not really relevant because I got up and down confused.

The third approach would be to go completely with the American system, using an American mould and American mat holder. This would seem like a sensible way to have started, but my American display moulds are in sad shape: they are dirty, heavily used, and have unknown amounts of wear.

The American moulds work with interchangeable mould blades for the various body sizes. One basic mould (type U) is used for 24 to 36 point type, while the other (type T) is used for 12 to 18 point. I have never encountered any mention of display sizes between 18 and 24 so if such exists, I don’t know whether the T or U mould is used. The type T and U moulds actually only differ in one part, the right type block, which determines the position of the nick-side of the mould cavity (to the operator’s left, defining the bottom face of the type). All other size changes are done by positioning the right type block (defining the top face of the type). The actual casting size is determined by a mould blade kit which consists of 6 parts:

These parts are custom fitted to a particular mould, and you can see the serial number of the mould marked on the pieces. The spacer holds the left and right type blocks the correct distance apart and is the one kit part that is not tied to a particular kit or mould serial number—it is only specific to the body size. The spacer also limits how far the blade can open (to widen the type).

The blade stop, top blade, and main blade are fitted together to the mould so that when the blade is closed, its end (both main and top) are just flush with the front surfaces of the type blocks. This exactly ejects the type without the mould crossblock rubbing on the blade. The top and main blades are also fitted to each other so their ends are flush when the blade is partway open for casting type.

The top and main blade with blade stop, positioned as if installed in the mould, to show which surfaces determine the blade position. The back of the blade stop can be ground to adjust the overall blade position in the mould.

I have quite a few kits:

…but only two of these are complete and have the matching mould. Worse yet, here is my only 18-point mould blade kit:
The spacer and back cover are missing! As it turns out the back cover for an 18 point T mould and 30 point U mould are almost identical. There does not appear to be any close fitting involved (in a mould assembled with no front cover the blade can be visibly shifted up and down) so in a pinch I could use the back cover from a 30-point kit. The spacer is the critical part and since this is the only 18-point kit I have I can’t borrow the spacer from another kit.

So it looks like I might be making an 18-point spacer for an American display mould. The shape of the part is fairly simple and does not require extraordinarily precise machining work, except for its thickness, which must be accurate (and the faces parallel) to 0.0001″ to get properly-sized type.

In the meantime, I can only hope that my 49A display mat holder will pop up, saving me all this trouble!

Addendum

As often happens concerning the alignment of American display mats, I had my up and down reversed. The 36- and 12-point mats have the same alignment in both systems. Sizes smaller than 36 that use the Type U mould (e.g. 30 and 24) are lower in the American mould than in the English one, while sizes larger than 12 that use the Type T mould (e.g. 14 and 18) are higher in the American mould than in the English one. As a result, the 18-point mats I want to use in the American holder must be lowered by 3 points to fit the English mould. This could be accomplished by using the first replacement mat holder insert set (41A19, 20, 21) which lowers the mat by 0.050″ except that is the one set I don’t have. Even though this set is a standard accessory to the mould it would be just as much trouble to make as a custom set to raise the mat.

This still pretty much leads me into the third option.