Freeing up 1132 printer components - part 6

TURNING METAL RULER INTO PRINT WHEEL ALIGNMENT TOOL

The only diagram mentioning the Service Tool is below:

I did find the part that I believe is the Service Tool from the text, but it was named the Aligner - Type Wheel in a diagram in the parts catalog. 

The notch in the Aligner (circled in blue) fits over a button (circled in green) on each side of the print wheel assembly. The Aligner has an edge that extends between two characters on the print wheels, blocking the wheels from rotating when the assembly is pulled up by the two handles. It fits between the letters E and R on the wheel, which are adjacent in the arrangement around a wheel.

The characters are raised sections on the top of the teeth of the print wheel, The shoulders of the teeth mesh with the drive wheel below. It is into the shoulders between the R and E teeth that the alignment tool will fit. 

I bought an inexpensive aluminum ruler from the local hardware store, then cut it to length so it will fit a bit past the two buttons on the print wheel assembly. I notched out a slot on each side that will slide onto the buttons, with the edge of the ruler fitting into the shoulders of the print wheels. I then had to hold it down in place with zip ties to be sure that it kept the wheels locked in alignment. 

With the wheels locked, it was easy to remove the bolts and lift the print wheel assembly out of the printer. I had access to make sure the wheels and hangar pivots were well lubricated. 

The wheels turn freely and all the hangars pivot. The surfaces of the print wheels are rusty but that will go away after a few minutes of printing. This assembly needs no further restoration or lubrication. 

MORE DISASSEMBLY TO AID IN FREEING UP PRINT CLUTCH AND LATCH

I decided to do more disassembly of the printer mechanism in order to easily get to and manipulate the Print Clutch Dog, Print Clutch plate and Print Clutch Latch parts. I looked at the maintenance manual for the procedure to remove the print clutch shaft which would do the job. However, the procedure looks quite intensive.

By analogy, imagine reading the procedure to repair a part in an automobile, only to be told to remove the engine, transmission, doors, seats and all four wheels before reaching the part. On the printer, I have to remove the entire print carriage first. Next I would remove the print wheel assembly, which requires me to build an alignment tool first and install it to lock the wheels in the proper orientation before removal. Other parts come out before I could begin to remove the shaft in question with the print clutches on it. 

Among the parts I had to remove were the top cover, the side covers, the top back cover and two metal plates that sit around the carriage for cosmetic reasons. The last of those plates was challenging to get it. I ended up having to lift up one end of the carriage when I had unscrewed it (see below) then slid the plate partway under it to get it out of the machine. 

Clutch cam shaft and print wheel drive gear

REMOVING CARRIAGE

The instructions for removing the carriage are vague and have some internal contradictions. The manual says only to:

When necessary to remove the carriage, it should be done by removing the two large tip-up shoulder screws, one at each end. (Figure 4-14.) 

The problem here is that the diagram shows no screw labeled Tip Up Shoulder Screw and there does not seem to be any single screw on a side. The only possibility is that the Carriage Removal Screws from the diagram are in fact the Tip Up Shoulder Screws. However, the diagram makes this appear to be two screws on a side, one coming in from each end, which doesn't agree with the claim there is ONE screw.

Looking at the left side of the carriage, if there were two bolts, front and back, as the diagram shows, then the front bolt is directly blocked by the timing disk. That would be a real pain to take apart just to get the carriage off.

Timing disk in front of shoulder bolt

To lift the carriage I needed to take the entire top cover off of the printer, giving me the room to pull the carriage directly up. I then discovered wiring connected to the carriage which had a connector inside the carriage that I could pull off to disconnect the wiring.  There was also a ground strap that would have to be detached in order to lift the carriage out. None of that was documented in the maintenance manual. According to that manual, all you need to do is remove the two screws. Hah. 

Plate to remove, blocked by carriage

Wires running to carriage

Plug disconnected

Ground strap

Top back and sides removed

When I could finally see the Carriage Removal Screws that I was unfastening, it was clear that the screw is in fact a single long bolt that is only threaded at the end, rather than two screws as it appeared in the IBM diagram. 

Removing shoulder bolt

I was initially concerned 

The carriage assembly is pretty heavy and awkwardly shaped. I am going to work out a method sliding a board underneath it, then slide the carriage out one side of the printer. The alternative would require two people to safely lift it out. 

REMOVING PRINT CLUTCH SHAFT

I had already removed a bar with a comb that kept the 120 print clutch cams spaced evenly. This will be inserted over the restored clutch cams when I am ready to reinstall, held in place temporarily by strings, and used to keep all the Print Clutch Dogs inserted on their Print Clutch Cams during the insertion. 

Again the manual becomes vague: 

Remove the bearing caps after removing the three screws in each. 

There are no illustrations to show where these are, nor the three screws. Nothing in the maintenance manual, the theory of operations manual, or the parts catalog. I had to work this out by examination. It does require the carriage to be lifted out first since one of the three bolts is blocked by the carriage. The caps are shown in yellow below with the three screws under the red arrows.

The actual bearing caps in the machine can be seen with one of the three bolts not visible as it is under the carriage:

I ran out of time in the shop to finish pulling the carriage out thus couldn't unbolt the bearing caps to get at the print clutch shaft. Those bearing caps also hold the print wheel drive gear; these are very large metal pieces. Next time I will pull the bearing caps and then lift the print clutch cam shaft out of the machine to work on it at the bench.