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Mark V control sheave replacement
Posted: Fri Mar 21, 2025 5:27 pm
by LeoB
Can anybody tell me how to replace the Control sheave from the inside of the headstock? I have the sheave removed from the idler shaft, but can't get it out of the headstock. Does the motor need to be removed?
Re: Mark V control sheave replacement
Posted: Sat Mar 22, 2025 12:39 pm
by DLB
I normally remove the motor. I think you can get away with removing just the five motor pan screws and lowering the motor to create a gap. This doesn't save many steps, but if the wiring is long enough you don't have to mess with the wiring. The motor and pan can sit on the bench tubes and the wiring is usually long enough to allow it to move or roll it a bit, creating the opening you need. The machine should be unplugged and the belt cover out of the way before you get this far.
- David
Re: Mark V control sheave replacement
Posted: Sat Mar 22, 2025 1:58 pm
by LeoB
Thanks for the quick response. I actually lifted the powerhead up to remove the bench tube support and removed the powerhead. Once on the work bench, I was able to remove the sheave past the lower sheave attached to the motor.
Re: Mark V control sheave replacement
Posted: Mon Apr 21, 2025 7:33 pm
by Koatley
You guys have a preferred source for new Control sheave parts?
Re: Mark V control sheave replacement
Posted: Mon Apr 21, 2025 11:11 pm
by JPG
SS Inc.
Re: Mark V control sheave replacement
Posted: Tue Apr 22, 2025 1:14 pm
by chapmanruss
Koatley,
Welcome to the Shopsmith Forum.
If you are having a problem with the Control Sheave and it needs replacing the best option, is as JPG stated, buying a new one from Shopsmith from right here on their website. It is part number 515556. Buying a used one may have you ending up with the same or similar problem you already have. You didn't explain what problem you are having with the Control Sheave so that is my best advice at this point.
Re: Mark V control sheave replacement
Posted: Sun Apr 27, 2025 12:49 am
by Koatley
The bearing and pin on my SS Control Sheave both need to be replaced. I have a 1954 with the Gilmar belt and was hoping to not have to convert everything to V belt.
The previous owner also had a collar installed on the end of shaft - I’m guessing to aid in retaining the bearing/pin
This collar was apparently damaged when pin broke.
I’m in beginning stages of restoring but again hoping to stay with Gilmar belt at least initially
Re: Mark V control sheave replacement
Posted: Sun Apr 27, 2025 1:22 am
by Koatley
Photos of my 1954 SS (Gilmar) Control Sheave
Re: Mark V control sheave replacement
Posted: Sun Apr 27, 2025 12:45 pm
by chapmanruss
As you noted that clamp was added and not OEM. The Control Sheave can be replaced without having to convert to the Poly V Drive. The Control Sheave is the same and the fixed Sheave side has the Gilmer or Poly V Drive attached to the Idler Shaft. Although I can't tell if there is any damage to the Speed Control Assembly do carefully check it.
Re: Mark V control sheave replacement
Posted: Sun Apr 27, 2025 12:54 pm
by JPG
Looks oily/greasy to me. Suspicious at least. Thorough overhaul recommended!
Note the pivot(roll/tension/retaining) pin has been replaced already.