I have been rebuilding my Powermatic 45 lathe and have come across a bit of a mystery putting it back together. The lower part of the variable speed assembly has been put back together according to the schematic and pictures I took. The vs cam is installed correctly. The adjustment arm and roller bearing are installed correctly. I have the vs control set to STOP and the cam is oriented correctly for the mini switch to work. NOW…the problem is that I’m unable to set the speed to stop because the vs arm/bolt bottoms out on the bearing plate. The vs pulley should be open enough for the belt to drop down to the shaft. AND when I turn the speed control it moves the vs arm/bolt even closer.
I’m not sure if all that makes any sense. I can post more pictures and please ask any questions you have. I worked on this all day and had two other tech savvy people in my shop who couldn’t solve the mystery. Can you? Any help is appreciated. I’m out of work until I can get this thing running.
Thanks!
Jason
Replies
I'm not sure I follow all that. I have a PM #90 lathe with a variable speed drive and stop switch. My lathe has a minimum speed achievable with the variable speed drive, and the lathe only stops when the stop switch is engaged. So I'm not sure what you mean by "The vs pulley should be open enough for the belt to drop down to the shaft." On mine the belt stays engaged all the time.
Yeah, it’s confusing. There is a positive stop when the shoulder on the cam hits the vs arm bearing. Meaning it keeps the vs control between the highest speed to stop. When it gets to stop there is a mini switch that turns the motor off.
If you look at the belt, the pulleys should open far enough to lower the belt to slow the speed down. Right now it is “stuck” in the high speed position.
That might have muddled the conversation, but I hope that clarifies.
Thanks for responding.
-J
Is this just because it is not running?
My ancient Walker-Turner lathe has a reeves drive too.
If it is not running you can't change the speed - when static, if you try to speed it up, the drive pinches and jams on the belt and when you try to open it for slower speed, nothing happens because it depends on the running pressure of the belt to push the two tapered wheels apart.
And don't try to change speed if its not running. I think that's what happened to my Delta. It jammed on one speed and eventually the Reeves pulley self destructed.