What is holding this bushing on?

[roger wiegand]

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I'm trying to replace a handle that is used to turn a screw on a small jack. Both of the set screws have stripped out making it impossible to tighten the handle on the shaft. I removed the set screws and pulled on the plastic knob hard enough to pop it off the brass bushing on the end of the shaft. Now the bushing remains. It spins freely on the shaft and nothing I've tried so far will budge it. I can see no evident means of attachment. I've been fairly forceful with it, holding the bushing in a vise and hitting the shaft with a hammer using a punch, but it doesn't move at all. I have a feeling I'm missing something simple. Any thoughts before I try cutting it off? Thanks!

[Dave Richards]

It is probably due to damage to the threads where the set screw bit into the shaft. I've seen something similar with anesthesia machine O2 flow control knobs when they got spun on the shaft. Even with the set crews removed it would be difficult to pull the knob off the needle valve shaft and to get the knob back on, I'd have to file down the burrs on the shaft.

[Al Launier]

Without seeing the knob to get a better perspective of how the knob & set screws was assembled initially, from what I can see, the knurled piece on the end of the threaded part might have been a "slip fit" over a machined shaft end of the screw and then the end of the shaft swedged to contain the knurled piece. So, if this holds true, then the knurled piece might be freely rotating due to the "swedge" loosening up. Just a thought based on what is shown.

[Tom Stenzel]

The plastic knob would have covered the end of the shaft, it couldn't have been peened to keep it on.
If I had to remove it I would slit it with a Dremel and break it off. Even tapping the end of the shaft with a punch can spread it a bit, DAMHIFTO!

If the replacement knob has setscrews and there are no flats on the shaft for them I would file them on. Optional if you think you need them.

-Tom

[Scott Shepherd]

That's a threaded bushing that's used to put inside a molded handle. The threads are what's holding it on, and banging it with a hammer is going to make it more difficult to get off. You need to hold the threads and rotate it off with vise grips or something at this point, then repair the threads on the shaft once it's off.

[roger wiegand]

I don't think it's threaded as it rotates freely on the shaft in both directions. I'm thinking that Dave may have the cause and Tom the answer. I'll slit it tonight and see what I find. And yes, I was planning to file a couple flats on the shaft to better hold the new knob, as it needs to take a moderate amount of torque in both directions in operation.

This is pretty much the knob I took off.

[roger wiegand]

To complete this, Dave was almost right. What happened was there is a groove machined in the steel shaft where the set screws engage. The brass of the bushing had mushroomed outward into this groove, effectively locking the bushing onto the shaft. Back to woodworking.