As part of test-fitting the parts for lead-and-rule casting, I found that there is a critical size difference between the American and English pump bodies.

English pump on the right, American pump on the left. Note difference in size (red arrows) as well as adjusting screw and steel wear surfaces (blue arrows).

Both these pumps take a ⅞″ diameter piston.

The section of the pump that the Pump Body Lever pulls up on to counter the downward push of the Pump (Piston) Lever is wider on the American pumps than on the English pumps, and the presence of the adjusting screw limits the bulkiness of the ends of the Pump Body Lever. This means that you can’t use an American pump on an English caster (or vice versa) without also changing the Pump Body Lever to match the pump. The Pump Lever might also have to be changed but I have not compared the piston stems to see if they are the same size. The stems definitely look different, with the American one being cast while the English one is machined.

I’ll have to look through my parts stock to see if I have a set of American pump levers. I certainly hope the other end of the levers is the same on both casters!

You can also see in the photo where the English pump bodies are fitted with steel wear surfaces where they slide against other parts.

One thing I would like to be able to do with my Monotype Composition Caster is to cast spacing and rule.

There is a kit of parts required to make the change-over, and I now have most of the necessary pieces:

• A Lead-and-Rule mould (mine is fitted for 3 points thickness)
• A special pump body with nozzle position altered to match the special mould
• A micrometer wedge and stand assembly which determines the exact stroke length of the mould blade
• A piece that attaches onto the centering pin arm to operate the clamp on the mould
• An automatic cutter mechanism, although mine is currently a lump of rust

Pieces that are still missing but that I can either cobble together or forego as useful but nonessential:

• Rule guide tube which keeps the rule from buckling or sagging between the mould and the cutter
• Mould blade drive linkage which reduces the type carrier lever stroke to just over ¾″ and adds a double-acting spring box

For now I just want to see the machine casting spacing so I don’t need the cutter operational, and so I don’t need the guide tube either. I think I have determined how to cobble together my own linkage as well.

While I had the caster down for a metal switchover, and the mould out as well, I decided to try fitting the pieces I have. One thing I found strange was the large number of parts which the installation steps required one to remove from the caster (from the booklet Directions for Changing from Type Casting to Lead & Rule Casting):

• Bridge
• Both Type Channel Blocks
• Type Carrier with its connecting rod and shoes
• Type Pusher and Guide
• Bridge-Lever Connecting Link (the one I forgot to hook up earlier this week)
• Piston and Pump Body
• Galley-pan Support
• Pin-jaw-tongs Spring and its links
• Locking-bar Cam Lever (disconnect only, do not remove)

Removal of most of these is indeed required to make room for the rule casting parts. I didn’t have to remove the Galley-pan Support, but if I had tried to fit the automatic cutter I likely would have. The Pin-jaw-tongs Spring and links are in the way of the linkage used by Monotype, but the home-made linkage I have in mind does not need this removed. Disconnecting the Locking-bar Cam Lever is probably to prevent the racks from wandering loosely when unlocked (which they can do when the Pin-jaw-tongs Spring is disconnected). The problem with letting them wander is that on each cycle, when the locking bars engage again, the racks will snap to one of the 15 or 17 positions making a loud snap noise and causing undue wear to the locking bar and locking teeth on the rack.

I have an English caster, so removing the Type Pusher requires removing the Rear Buffer (absent on American casters), in turn requiring removal of both sets of rear tongs.

Another side effect of the English caster is that the clamp-on extension for the centering pin arm does not fit very well. The English centering pin arm has some extra lumps of metal to accommodate the English-style low-quad mechanism and these make for a very tight fit for the extension. I find it interesting that the diagram on page 284 of The ‘Monotype Casting Machine Manual shows this extension mounted on an American-style centering pin arm even though this is a manual for the English casters.

The 3 point Lead and Rule mould mounted on my caster

The Type Pusher (arrow) crashing into the Lead and Rule mould if not removed

The special lead-and-rule pump in place in the (empty) pot. Note the distinctive long space between the nozzle location and the support pin at the left end.

I did some other cleanup work on the caster and on some of the removed parts—the Type Pusher Guide was a solid mass of greasy dirt. This included cleaning out the pot, and once that was done I put the special Lead-and-Rule pump body onto its supports and tried to swing the pot closed. It wouldn’t close because, as it turns out, you can’t use an American pump on an English caster because the pump body lever sizes are different.

The the results of this experiment are that I have a few cleaned parts, some notes and measurements to make my own blade drive rod, and that in order to use this I’ll have to find a set of American pump body levers. I may have some in my parts collection.

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.

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.