Speed control problem

[JoeSark]

I have 510 that is working fine aside from one issue. I can run the speed to high just fine, but going back to slow, it stops about halfway. When I took it apart, the keyway on the upper sheave had shifted. When I replaced it, everything worked fine for about a week, and it's doing the same thing again. What causes this to happen?

[JPG]

Please define "shifted", stopped.

i.e details.

[JoeSark]

When turning the speed control, the wheel stops turning when the speed is at the H setting. When I said the keyway is shifted, I should have said the key was shifted in the keyway. The key seems to slide with the moveable sheave, and then, when the sheave tries to slide back together, the key catches on the fixed sheave.

[edma194]

Does the key seem to be bent?

[DLB]

When turning the speed control, the wheel stops turning when the speed is at the H setting. When I said the keyway is shifted, I should have said the key was shifted in the keyway. The key seems to slide with the moveable sheave, and then, when the sheave tries to slide back together, the key catches on the fixed sheave.

One end of the key should have a slight bend, that feature goes into a hole near the end of the shaft keyway that's under the Poly-V (aka fixed) sheave. When the fixed sheave is in place the key is essentially trapped by the slight bend that's in the hole. So it should not be able to slide with the control sheave. I think the problem is something to do with those features. Maybe a PO installed a key without the bend, or something has happened to it.(?) Much less likely, something wrong with either the keyway in the shaft or the keyway in the fixed sheave somehow allowing the key bend out of the hole.(?)

- David

[JoeSark]

Thanks, I'll take it apart tomorrow, and then I can try to figure out how to post pictures of it.

[JoeSark]

20240812_183227.jpg (157.14 KiB) Viewed 1438 times

20240812_184504.jpg (144.09 KiB) Viewed 1438 times

Well, I hope the pictures show up on the thread, because all I see are fule names.

[JoeSark]

I meant file names. Looks like they showed up.

[JPG]

Yep - no bend.

[JoeSark]

It looks like I could tap a slight bend into the end, and then file a sharp corner to the inside of the bend so it mates with the recess in the shaft. I'll try it this evening so that hopefully, I can use it while waiting for the new part to arrive. I've been a shopsmith owner for about 3 years now, and the more I use it, the more amazed I am at the thought that has gone into this system. I've never seen a machine that lends itself to user repair and shop made upgrades like this.