porkchop travel question

[timsch]

The worm gear that the dial turns has a limit shown in the picture that I don't know is right. There's a limiter screw for one direction, but when disassembled, I don't see what limits the travel of the porkchop the other direction and why it wouldn't just be rotated off the end of the worm gear. It's binding up at this point.

I just pulled the c-clip off the worm drive shaft, allowing it to slide about 1/4", enough for me to lube it with 3-1 oil. There was binding up along the full travel of the porkchop before lubing. Now it moves pretty freely, but binds up almost fully at this point shown. The teeth on the porkchop are worn don't appear excessively so to me. I've not added any lube to the worm screw threads yet.

Is this supposed to be?

[DLB]

The pork chop (aka quadrant) should have full range of motion and travel all the way through disengagement with the worm gear.

Look at it (and add a pic?) from straight on so that you can see how the pork chop aligns with the worm gear shaft. The pork chop should be dead straight and centered. The arms used for attaching the pork chop at its hinge point should be straight. The pork chop swings on a roll pin (spring tension pin). The holes for that pin in the arms should be a reasonable fit and not be oversized, which allows a sloppy fit that can bind the pork chop. Chances are good that you'll see a problem with some of this. I suggest the Bill Mayo headstock improvement, see the first post in the first thread under Maintenance and Repair, 4th attached pdf. His solution is good for repairing many salvageable speed controls and ruggedizes even new ones.

Note: While I recommend repair before it gets worse, the pork chop does not actually travel quite this far in normal operation. You are, I think, slightly past 'Slow.'

- David

[timsch]

Here's the front view. Definitely misaligned, and has been for some time.

IMG_20220218_125812793.jpg (102.48 KiB) Viewed 1014 times

[DLB]

This is fairly typical. It generally starts from sheaves (control and/or floating) that are hard to slide on their shafts. We crank harder on the speed control, and this is the weak link. You can see that the extreme wear on the gears gets progressively worse towards slow, this is probably why it is binding. I've highlighted the gap in your picture, this is too big indicating the legs are splayed somewhat. Holes for the roll pin might also be enlarged, not seen in this view.

Gap

timsch speed control.jpg (104.49 KiB) Viewed 1003 times

IIWM I'd get a new pork chop and improve the rest per the Bill Mayo document. You might be able to save the pork chop by filing the teeth, but this one is pretty far gone.

I'm adding a picture of another speed control emphasizing hole wear. Once the pork chop is not running true hole wear is inevitable. I don't recall whose this is, it came from another thread here:

Speed Control 7 (2).jpg (180.07 KiB) Viewed 1003 times

- David

[timsch]

I was able to push the arms together and I got the pork chop centered. The pin has been replaced by the 10-24 screw that Bill recommended. Everything looks centered now. The holes haven't been worn out. Arm holes are within 0.010" diameter of the chop hole. I searched for a replacement quadrant but didn't get any hits for the pork chop alone, only the full assembly. I'm inclined to put it back together with what I have, lube it well and see how it goes.

[rogersk]

Quadrant.png (197.9 KiB) Viewed 981 times

Shopsmith still shows the quadrant available by itself, but you should call first to make sure.

[jsburger]

I was able to push the arms together and I got the pork chop centered. The pin has been replaced by the 10-24 screw that Bill recommended. Everything looks centered now. The holes haven't been worn out. Arm holes are within 0.010" diameter of the chop hole. I searched for a replacement quadrant but didn't get any hits for the pork chop alone, only the full assembly. I'm inclined to put it back together with what I have, lube it well and see how it goes.

Is not item H on this link is what you want?

https://www.shopsmith.com/service/mostf ... dparts.htm

[timsch]

Thanks Roger. Yes, that's it, JS.