The one ribbon I have to test out composition casting on my Monotype was in rather sad shape. It had several kill lines which cause casting problems by allowing the mould to chill too much, and it had also been damaged quite a bit during my attempts to adjust the ribbon feed on my air tower.

I used PVA (white glue) for the repairs, but in retrospect this seems to leave very stiff areas in the ribbon so a glue that sets softer (perhaps starch paste) would have been preferable.

The main job I undertook was to cut out the kill lines and splice the remaining ribbon together.

The kill lines removed from the ribbon. Some have been scavenged for repairing torn tractor holes.

The six splices from removing kill lines.

Most of the splices were lap joints, although in the fifth joint I cut the ribbon wrong and had to butt the two ends together then join them with tissue. The gap in the butt joint was air-sealed using correction tape. Because of the width of the tissue this joint has a particularly long stiff section from the glue.

In the third and sixth joints the killed line had an odd length, so I had to keep the line-kill punch to make the tractor holes come out even.

Several of the punch holes should be cleaned up so they pass air properly, and the roughness from the lap joints may cause excessive air leakage around the air bar. I have already re-adjusted the air bar to raise higher than normal to allow the rough joints to pass without snagging.

I also repaired a couple of tears using tissue, and torn tractor holes using edge strips harvested from the removed kill lines:

There were also a pair of small holes torn, probably caused by the metal supports for the two drag bars that provide slight tension for the ribbon passing over the top of the air tower. For these I tried correction tape (a very thin tape for covering over printing on paper to allow for corrections) applied to both sides so there would be no exposed adhesive. This stuff is so thin I wonder if I should have used it to make all butt joints in the ribbon. Although I can experiment this way on the kill lines, because I used PVA on the good ribbon I can’t take the lap joints apart to turn them into butt joints anyway.

Having found that my patched-up ribbon would not run through my caster’s air tower because of the low clearance under the raised air bar, I tried a different adjustment procedure to maximize the clearance available for ribbons in poor condition.

The Bar Length and Air Valve adjustments are the same as in the normal procedure.

Bar Sleeve Adjustment

This adjustment differs from the normal procedure in that it sets the length of the rod stroke to the longest possible amount which still ensuring that the ribbon stops moving before the air bar starts clamping.

The rod end 4G1 should still be clipped onto the pin 3G1 on the pressure lever. Turn the caster handwheel until the air tower lever is in its downwards stroke and the pawl ring lug has just stopped its counterclockwise motion against its stop screw.

Loosen the Bar Sleeve locknut, and screw both the locknut and sleeve clockwise (down) until the sleeve and its washer are no longer against the underside of the lug on the air tower side cover. Now carefully turn the sleeve counterclockwise (up) until the sleeve and washer just contact the underside of the lug, then give them one more turn. Tighten the locknut.

Verify that the pin on the end of the paper tower lever still has some downward travel before hitting the end of the slot in the lower end 4G3 of the rod by carefully watching it while the handwheel is advanced a few degrees. There should be about 1/32″ travel (from the one turn of the sleeve).

Air Bar Pressure Spring Length Adjustment

This differs from the normal procedure in that the spring length is adjusted to ensure a particular amount of spring compression, leaving the rest of the pressure lever movement for raising the air bar.

With a ribbon loaded in the air tower, rotate the caster handwheel until the pin jaws are closing.

Use a pair of wrenches to loosen the two locknuts 2G7 without loosening the studs 2G4. Turn the adjustment screws 2G6 clockwise by hand until they contact the pressure bar. Turn them back counterclockwise ⅓ turn. Turn the locknuts until they contact the adjustment nuts, then hold the locknuts steady while you turn the adjustment nuts counterclockwise against them to lock them.

Having done the adjustments this way, my lumpy ribbon seems to run through the air tower without jamming, at least when done by turning the ribbon feed wheel by hand.

I only have one punched ribbon to test out the composition casting on my Monotype, and this ribbon is wanting in more than one way.

For one, it was my first (and I hope only) attempt at punching a ribbon on the Monotype keyboard. About a quarter of the ribbon is kill lines (when you make a punching mistake on the keyboard, there is no backspace or delete, so the best you can do is kill the entire line and start over). Although the caster will not cast any type for such lines, it still cycles through the ribbon at the same speed as if it were casting, and while it is doing this the mould is still being chilled by its cooling water supply. As a result, when the end of the killed line is reached and the machine starts casting again, there is a good chance of miscast types or even a nozzle freeze (and nothing casting) until the mould warms up again.

The other problem is that I was using this ribbon while I was testing and adjusting the air tower on my caster, so it has a large collection of torn sprocket holes and other tears as well.

I spent some time in the past few days trying to repair the ribbon. I cut out the kill lines and spliced the cut ends together, repaired tears with tissue, and used some of the cut-out kill lines as a supply of sprocket-hole repair strips.

The end result is a ribbon that is entire, but because of the thickness of the splices and patches, will not run smoothly through the air tower because it is set for minimal lift of the air bar. When the bar is raised, there is only enough clearance beneath it for 2 or 3 thicknesses of paper, and a lap joint is a minimum of two thicknesses, plus any roughness and glue thickness.

To enable this ribbon to be read, I have readjusted my air tower to provide more clearance for rough or damaged ribbons. Details on this procedure in another post.

Well, I managed to fool WordPress into accepting an animated GIF so here’s the one I made of the ribbon feed mechanism being operated manually. It’s a little rough because the original pictures were taken with the tower lying on the table, free to move around a bit. Nevertheless the basic steps can be seen:

1. The drive pawl engages the ratchet wheel.
2. The locking pawl clears the ratchet wheel.
3. The pawl ring rotates counterclockwise, turning the ratchet wheel with it.
4. The locking pawl engages the ratchet wheel.
5. The drive pawl clears the ratchet wheel.
6. The pawl ring rotates clockwise, with the ratchet wheel stationary.

Once the operating rod for the paper tower is adjusted, there are four adjustments left, all affecting the Air Bar 2G, Pressure Bar 3G, and air feed. Two of the adjustments are on the Connecting Bar 4G that links the Paper Tower Lever to the Clamping Lever, one is the screw 3G3 that actuates the air valve stem 2G8, and one is the stop nuts 2G6 that limit how far the Air Bar Springs 2G3 can expand. The two adjustments on the Connecting Bar are the overall length of the bar and a stop that limits is upwards travel. On older casters before serial number 503 the latter adjustment did not exist; instead there was a simple spacer tube and wear was compensated for by adding a washer to the end of the spacer tube.

The adjustments in Casting Machine Adjustments consists of setting the valve screw 3G3 to a specific amount of projection below the arm it is set in. Then a sheet of caster ribbon is used as a feeler gauge between the 3G3 screw and the valve stem, allowing the Air Bar Spring length to be adjusted. Third, the connecting bar length is adjusted to set the clearance between the air bar and the cross girt to three ribbon thicknesses just as the clockwise rotation of the pawl ring stops (and thus the ribbon stops). Fourth, the stop collar on the connecting bar is adjusted so the connecting bar has about 2 points of total motion. The book mentions that these adjustments interact with each other and that it might be necessary to repeat some of the earlier adjustments.

I have an alternative adjustment procedure which generally avoids the need for repeating adjustments, and also does not rely as much on rote distances.

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The book Casting Machine Adjustments provides procedures for adjusting the Paper Tower, but I find that these adjustments are given in the wrong order (later adjustments can affect earlier ones) and some of the adjustments are rote settings which may not be appropriate on an older caster exhibiting wear in some of its linkages.

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While refurbishing the paper tower for my Monotype caster I found that one of the pivot pins (part 16G, on which the locking pawl pivots) was slightly bent, and was nearly impossible to straighten properly. The bend was hard to see except when the pin was installed, and the pin was too short to tell exactly where it was bent.

Rather than trying to fix the existing pin I made a replacement one.

The geometry was fairly simple, but the dimensions had to be accurate to ensure that the pawl did not have too much play, which would have led to increased wear of the ratchet wheel and misalignment of the ribbon holes over the air ports. It fits well, although I cut the threads a bit deep, possibly weakening the threaded portion of the pin, but I don’t think there is enough pullout force to break it.

The paper tower is now reassembled, except for the two lower covers, and has been reinstalled on my caster. To discourage future air leakage around the base of the tower I applied a thin coat of spray adhesive to the mating surfaces. I actually sprayed it onto a piece of release paper, then applied that to the area around the ports, so that over spray would not enter the actual air lines. The adhesive should be strong enough to resist the air pressure but still weak enough not to prevent future removal of the tower. I would have used brush-on gasket sealant if I had had any.

The next job is to adjust all the linkages.