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Clausing 15" variable speed DP: troubleshooting speed adjustment


Apr 17, 2022
I recently acquired a 15" Clausing 1670 Variable speed drill press (1966) in pretty good shape ($450). I need some help troubleshooting the speed adjustment.

I can only access the top half of the speed range. if I try to go any slower the front pulley faces move too close together and push the belt off. My initial thought is that the belt on it is too wide or too long. Does this make sense? could it be anything else?

I did need to replace the variable control hand wheel bolt. Clausing charged $26 to ship a 1/2" bolt in an envelope, which makes me hesitate paying $100+ for a new belt I may not need. Thank you.


Dec 30, 2008
I just measured the belt width on my Clausing 1765 VS. It's 7/8 inch. seems to work fine. Perhaps your model takes the same belt width.

It could be the belt is too long also. How does it ride at the other extreme?

I do need to "exercise" the drive regularly to keep it limbered up. But it's not thrown a belt on me.