• January Turning Challenge: Thin-Stemmed Something! (click here for details)
  • Conversations are now Direct Messages (click here for details)
  • Congratulations to John Lucas for "Lost and Found" being selected as Turning of the Week for January 13, 2025 (click here for details)
  • Welcome new registering member. Your username must be your real First and Last name (for example: John Doe). "Screen names" and "handles" are not allowed and your registration will be deleted if you don't use your real name. Also, do not use all caps nor all lower case.

Old Powermatic

L

loberg

Joined
Dec 24, 2007
Messages
102
Likes
0
Location
Redwood Valley, CA
I'm substituting for a shop teacher and the school has one of the old Powermatic (green monster). I think the threads are 1 1/2 X 8? Does anyone know for sure? It starts at 1000 RPM; is there any way to reduce the speed without spending a fortune? I would like to help the class so more students enjoy turning by supplying some parts and/or information on this lathe. Any suggestions other than buying a new one (no $ for education here).
Thanks
 
The spindle threads on the old PM90 that I owned were 1 1/2-8. The speed should go down to nearer 500. If you remove the belt guard, you can inspect to make sure that the belt rides all the up to the top edge of the pulley under power. If it doesn't, you might be able to replace the follower bearing behind the speed control lever. This bearing pushes the shaft of the pulley to the left, closing the pulley, and the belt rides higher in the pulley. That will be your slowest speed.

The alternative is to replace the motor and drive with a VFD combination. I have heard of folks doing this, but I know very little about the procedure. Maybe someone here on the Forums has done this.
 
I just checked and there's a complete owners manual for the Powermatic PM90 in PDF format on the Old Wood Working Machines web site (www.owwm.org). It has a speed chart showing the lathe operating at 300rpm. There also is a diagram and instructions on how to reset the speed ranges on the lathe. It may be of some help.
Tim Carter
 
It depends on the model of 90 you have. There were 2 general versions one with a jackshaft and one without. The ones without would go down to 500 rpm generally, although the speed wheel is only marked at 1000. The START mark is actually 500 which is when the rocker switch turns the lathe on.

I added a VFD to my 1hp 3hp setup and I could spin from 50ish to 4000. Factory-mation, FM50 runs about $100 plus a quality potentiometer and enclosure - I had less than $160 into the VFD conversion when complete.

They are BEASTS and build like tanks. The spindle is amazing and the entire setup is built for decades of abuse.

Michael
 
You must log in or register to reply here.
Back
Top