I’ve started tracing all the pneumatic plumbing on my Monotype caster, and at least now I’ve identified all the various control valves hanging off the table apron. This may be old news to any Monotype pros who may be out there, but I have found that the documentation for these various valves is scattered throughout at least three different books, and even at that it is often incomplete. I have found nothing discussing the compatibility of trying to use several of these options at once, or their compatibility with the three different matcase sizes.

The left side apron below the paper tower

On the left side of the table below the paper tower is a valve and mounting plate which serves two purposes:

The mounting plate serves as a distribution manifold for the Quadding & Centering system via the four flare fittings pointing upwards and three connections on the rear.

Attached to the mounting plate is the control for the Unit Shift system. The knob on the left turns the Unit Shift system on and off, and the three flare fitting on the right connect to a hold valve which on each cycle stores the Unit Shift selection from the end of reading the ribbon up until the matrix jaws close fully (during this time the ribbon is being advanced to the next position). This hold valve is not installed in this photo, but it is reset at the closing of the jaws by the small bolt head visible on the right, attached to the cam lever arm for all the jaw motion.

A caster without Unit Shift might have a dummy plate here instead of the control plate, or the mounting plate might be a smaller version that does not have any provision for Unit Shift at all.

Rear apron of table

On the rear apron of the table there are three pneumatic controls. As shown in the photo, left to right, they are the pneumatic mould blade signalling, Quadding & Centering control, and Unit Adding control. Each of these is attached to a mounting plate that hangs from the edge of the table and has several under-table air lines feeding into the rear of the plate.

I use the general term “pneumatic mould blade signalling” because the same valve is used in several different ways depending on the actual mould in use. This uses a ribbon signal instead of special mats with shallow cone holes to select one of two alternative ways for the mould to open. One possibility is the signalling for low quads on a standard composition mould, allowing one to make low quads on any row of the matcase and thus of pretty much any width. Another possibility is controlling the Duplex Mould whose upper blade only covers the top half of the cavity, used to suppress the casting of a diacritical mark (e.g. an accent) above the main character in the mat. There is also a triplex mould which requires two air signals; in this case this valve would have a twin beside it to control the second signal. In any case use of this signal requires support on the bridge and (in the case of the American bridge) another valve on the table top near the right rear corner. Turning this option off or on is done by inserting or withdrawing the large screw that projects from the top of the control valve.

Quadding and Centering are controlled by the two stacked valves at the center of the photo. These valves resolve the signals from the paper tower to determine if either of these features should be engaged, and the resulting air signals are routed through the base plate mentioned above, on the left apron below the paper tower. From there they go to two actuators on the paper tower and one valve at the end of the galley. There is no way of turning this option on or off.

Unit Adding is controlled at the valve located at the right in the photo. My caster is not equipped with this option, and so the valve is replaced by a blank plate that routes the air lines as if the option were turned off. With the option installed, there is a knob on top of the valve which turns the option on or off. The field-repaired air lines shown in a previous post are supposed to feed into the back of this valve’s mounting plate.

Not shown is the valve for use with 17-column (instead of 15-column) matcases. This valve is located near the left rear corner of the rear airpin block, and has a knob to enable or disable this option.

Of all of these options, only Quadding and Centering is made obsolete by driving the caster by computer. All of the others give the computer more versatility in terms of adjusting type width or generating low quads. Yet this option is the only one that cannot be turned off.

Over the next few days I will be removing and cleaning all these valves to ensure they operate properly.

The ribbon I punched. It represents about 8-10 lines of text but is twice as long as necessary because of all the mistakes I made…

Inspired by my recent attendance at Monotype U 8, and given that I kept the ribbon I had punched on the keyboard there, I have decided to reinstall the paper tower which I had removed from my Monotype caster when I was first getting it working. At the time I had intended to make a computer interface that replaced the paper tower, but those plans never gelled so at least for now I’m putting the paper tower back on.

The paper tower, which has been sitting in a parts bin for several years.

Putting this on is a tricky job because 4 of the 6 screws that attach it to the main table are covered by other parts. The two rear screws are covered by the draw rod for the mould blade, and the two front screws are covered by the draw rods and spring box for the tongs. Clearing the mould blade rod is easy: it is just a matter of removing the pivot pin for the bell crank allowing the rod to swing out of the way without even losing its length adjustment.

The paper tower in position with the mould blade crank pivot removed so the arm can be moved aside to provide access to the screws (left side of tower).

Reaching down with a long screwdriver.

The tongs spring box is another matter entirely. I recall having to remove a lot of parts from the topside to get these clear of the paper tower screws. As it turns out though, an extremely long screwdriver can be used to install these two screws.

I couldn’t buy a long and thin enough screwdriver so I made one. It manages to reach down all the way to the base of the tower and slip in beside the tongs draw rods to allow tightening of the tower base screws. The screwdriver tip is not as wide as the head of the screw so I can’t make the screw as tight as I would like, but I hope they are tight enough.

In addition to the paper tower itself, there are pneumatic controls associated with the paper tower to be installed as well: Center is the unit which stops the ribbon feed when quadding is in effect, and lower right is the buffer which holds the Unit Shift selection from the time the ribbon is read until the matrix jaws are closed.

The air piping under the read left corner of the table seems to be a bit of a butcher job, with one pipe crudely cut off and another one patched together using several joints of differing types, so I chose to take this time to review all this piping, properly identify all the valves, and clean them all so they work properly.

This is the culmination of a long three-pronged refitting of the pump on my Monotype composition caster. The three parts were disassembling, cleaning, and reassembling the pump head mechanism, refitting a pump latch mechanism scavenged from another caster, and making an extended-stroke pump piston rod to increase the volume capacity of the pump.

I reassembled the whole mechanism and adjusted it per manufacturer’s instructions. I found that the pump lever connecting link (a32H) not only has the obvious top/bottom asymmetry (the top contains a spring and plunger to pre-load the pivot) but it also asymmetric side-to-side. The way I had things assembled, the levers could not move low enough to engage the pump body and piston rod. After turning it around everything fit nicely.

I already had the pot fired up (so I could remove the pump body and replace the piston) so I proceeded to cast some type. After fiddling with some adjustments (since I did not have the appropriate reference cards at hand) I had it casting some nice, near-solid type.

36-point Rockwell Antique capital N (31 points wide), cast using Linotype alloy. At the lower right is a type cut in half to see how solid it is.

A close-up of the type cut in half. The piece on the right is the raw sawn surface. On the left, filing the surface smooth reveals a few small bubbles near the face of the type, but not enough to weaken the face.

I was also weighing the individual types and had some that weighed more than the sectioned one, but to get that I had increased the pump pressure and was finding that many of the types had flash bordering on being an outright squirt from the pressure of the molten metal lifting the mat a bit. I am using an American bridge which has no provision for increasing the downward pressure on the mat.

The extended-stroke piston rod I was making for my Monotype caster is now finished.

Now that it is off the mill, cleaned up, and has its handle put on it looks so much like it could have been a factory-made part. Except for the fact that the handle ended up a bit crooked.

But the proof of the part is in the pumping, so sometime this week I will be firing up the pot on my caster, finishing the re-installation of the pump mechanism, and after making all the appropriate adjustments that were disturbed by the disassembly, I will try casting 36-point capital Ms to see how solid they turn out.