Powermatic Model 91 speed control issue

[Ken Hartman]

Hey all,

Newbie here. I have a Powermatic Model 91 lathe. It's in very good condition, but I have a problem with the speed increasing on its own. With a bowl spinning it just gradually keeps rising in RPM. I just recently got it back together, new bearings, belts etc. Running great just wants to run away :)

I know a bunch of you guys have experience with the 90 models and this is the same machine, just with the riser blocks.

Any advise?

Thanks,

Ken

[Fred Belknap]

Not very familiar with that machine. It has a reeves drive and may need a new belt. They are said to be pretty good machines.

[William C Rogers]

Ken, I had a PM 90. The real PM91 that yours appears to be is quite rare. Nice job on the refurbish. I raised mine to mimic the PM 91, but never had that problem. I suggest you post on the OWWM site as there are many who have the PM lathe and can help.

[Bob Ballard]

Ken, does the speed control handle move as the lathe accelerates by itself?

[Ken Hartman]

Ken, does the speed control handle move as the lathe accelerates by itself?

Bob,

Yes it moves right along with the speed. very slowly, very strange

Ken

[Ken Hartman]

Thanks William I will try that

[Bob Ballard]

Ken,It sounds to me like the problem is in the speed control.dial It should have enough tension to keep the sliding side of the v/s pulley from moving on its own.