Sunday, June 7, 2015

Extremely close, but now I have to fix a part that I broke before this endless restoration of the 1053 is done


I added a knot at the end of the carrier return cord, installed it, put on the mainspring and tensioned it. Next, I installed the escapement cord. Now, with the slight shortening of the CR cord, there is a bit more tension on the cords although the spring loaded tensioner on the side is not pulled in to the desired line yet.

The changes was enough so that even when the carrier slammed to the extreme left due to failure to unlatch the CR mechanism, the cord stayed on both drums. I could unlatch the mechanism manually then resume spacing or tabbing to get the carrier over to the right again.

I can see that the problem is a failure of the carrier to push the margin rack leftward, partly due to the air cylinder keeping the rack from absorbing all the energy. I think the rack isn't moving fast enough due to residual good on the margin rack pins which slide left and right.

Margin rack, right side, top pivot cocks the rack to the right

Left side of margin rack, vertical lever connects to air piston to handle high speed carrier return

Full pivot for the left side of margin rack, piston rod at bottom goes to air cylinder offscreen to right

Air cylinder to handle the deceleration and cushioning of the high speed carrier return option
If it would move easier, it would complete the release of the CR latch. However, if it moves too slowly, the carrier bounces past the rack and continues to the left, without enough margin rack movement to release the CR latch. I will work on further freeing of the rack, plus work on the release so that it triggers even with a partial movement of the margin rack.

I am very, very close at this point, I think. I hope. Things will move quickly when I get the CR to unlatch properly, so this is the top priority. First I worked on clearing as much lube and resistance out of the rack and air cylinder as I could.

It still doesn't pop back when released, instead kind of oozing. This is typical behavior of IBM mechanisms once the lubricants of the sixties became the tar pits of this century. All I can do, unless I totally disassemble the affected parts, dip them in mineral spirits and reassemble, is to work some clean new light lubricant (I use a very light Mobil One synthetic) into all the sliding and pivoting spots, hoping to displace the old gunk through repeated cycling.

Next, I saw that the unlatch isn't triggered until the margin rack is moved to almost its full leftward extreme, something that happens with manual operation using the handcrank wheel, but that doesn't work right when it is returning rapidly under power.

white plastic is pivot for unlatching the CR mechanism, when pushed by the vertical bar to its right

The bracket at the right of the margin rack with its vertical bar
There is an adjustment to move the bracket on the margin rack end to be closer to the fulcrum that releases the CR latch. Even with it at its full extreme, there is a substantial gap between the fulcrum and the margin rack bracket arm that trips it. Since it is a arm bent at a 90 degree angle to the main part of the bracket, I thought I would try to bend it to lessen the gap. Instead, I snapped the arm off! ARRRGGGGHHHH.


  1. I know this isn't what you want to hear, but I would probably have the tang welded back on to the Overbank Guide Bracket (at least that's what it's called on a regular Selectric. Locating another one will be very hard, I think. A good welding/machine shop should be able to do it.

  2. I might have to get it fixed, but the part appears to be aluminum - it is certainly not steel like on ordinary Selectric mechanisms. I suspect welding won't work.

    This is only used for the high speed carrier return models with their air cylinder to cushion the deceleration - the piece in question unlatches the margin rack so it can shift over, preparing the cylinder for the rod to be rammed into it when the carrier strikes the left margin.

  3. This might be a pot metal, a less ductile, more fragile alloy, since it broke right off rather than bending at all. The inside where it broke has a granular appearance.