Adjusting the rotate character selection on the 1053 - part 4

 PRELIMINARY HOMING

The screwdriver set with Bristol heads arrived yesterday and I eagerly set out for the shop to adjust the preliminary homing position. It was much easier with the proper tool - loosened and rotated to the correct position. 

BALANCE LEVER

The balance arm is what balances the negative and positive rotation amounts. To adjust it, one has to set the machine to two different versions of the same unrotated (home) column - 'latched home' and 'I/O home' - so that these produce exactly the same position of the ball. 

Latched home is when the three selector latches R1, R2A and R2 are all activated, thus they are not pulled down by the bail. The R5, not being activated, blocks the balance arm from moving up. These conditions do not impart any movement to the pivot arm and it stays at its neutral position.

I/O home is when the R5 is activated but the R1, R2A and R2 magnets are not. Thus the three positive levers are pulled down, generating at +5 rotation amount, but the cam moves the lever up for the -5 which should deliver exactly the same amount of rotation in the -5 direction. The sum should be zero movement as well. 

This comparison is made with the ball shifted to the 'upper case' side. If the position is different, the balance lever is moved left or right to produce the same position with either version of the home column. 

Adjust by moving left or right

When I checked this setting it was already correct. 

ROTATE ARM MOVEMENT

The leverage of the turnbuckle rod on the rotate pivot arm depends on where it is attached relative to the pivot point of the arm. The rod attachment point is moved up or down until a -5 and a +5 move the ball the same amount from the home position, as judged by where the detent enters the teeth for those two columns. 

Arrow to part that is moved

This one worries me, as I have to set it as high in the slot as possible and I still don't believe I have enough range of swing to fully and reliably accommodate +5 to -5 rotations. 

FINE HOMING ADJUSTMENT

We want the detent tip to touch the sides of the teeth of the ball at a chosen point to maximize the chance that the ball locks to the correct rotate position and no damage occurs to the ball or detent mechanism. The ball is manually rotated clockwise, taking out any slack or slop and acting against the tape tension, and the tip must be to the right of the peak of the tooth by .015" to .025". 

The adjustment is made with the turnbuckle rod that couples the rotation selection mechanism to the bottom of the rotate pivot arm.  This refines the setting that we approximated by making the scribed line parallel to the power frame. 

FINAL PRINT SHAFT TIMING

The timing of the print shaft relative to the print cycle clutch is adjusted by loosening a gear and turning the print shaft manually to check that the detent touches the ball at the best place. A tilt 2, -5 position is hand cycled to the halfway point. 

The print shaft is turned by hand at this point to cause the detent to enter the tooth and then come back out until the detent is 'withdrawn halfway from the slope of the tooth skirt'. No diagram shows this condition so I will have to experiment until I think I have the right point.

Now that the print shaft is at the desired point, we continue hand cycling the print cycle until the ball begins to rotate back to its home column, stopping right when the detent touches the tooth edge. The print shaft gear setscrews are tightened to lock the shaft to this position.

We test that this occurred correctly by hand cycling two different characters with a -5 and a +5 rotate respectively. The detent must just start to rise into the tooth on the left side with a clearance of .001 to .015" from the left edge as it just clears. This must happen for both characters. 

Because of the imprecision of the procedure language above, I chose to hand cycle the -5 and +5 on my own properly adjusted 1053 and observe the detent entering the tooth to understand when and where to measure. 

This is set up now but I remain unsatisfied with the behavior of the rotation mechanism. It seemed to me that if I could increase the range of motion of the whiffle tree mechanism that converts the selection levers to a push or pull of the pivot arm, I might solve the problem. 

One possibility is that I might be able to move the position of the backplate holding the whiffle tree. To look into this, I disassembled the donor typewriter so that I could examine the possibility. It does not appear to be possible to change its position nor would it help. 

During disassembly

The other possibility is to increase the swing of the bail which rides on a pair of cams. In the picture above you can see the rollers on the bail swing arm with the selection latches near the top hanging down to fit under the bottom of the bail. I will look into this more during my next visit to the shop.

GLUING OF THE RIGHT MARGIN LEVER

When I checked my test where I glued the two margin levers of the donor typewriter, the joint was as solid as could be. I then fitted the halves of the right margin lever together, braced them with a small clamp and glued them. 

RIBBON COLOR TAPE I HAVE TO REPLACE

This is the plastic tape that IBM uses to transmit the pull when the ribbon color is shifted from black to red. One of the clips is shown, but the other side tore apart thus even this tape needs a repair. I have no tape at all for the 1053 I am restoring, but so far my tests with various plastic tapes have failed to find a suitable solution.