Powermatic PM66 Question

[Chuck Fischer]

So I picked up this old PM66, from the late 70's. The guy used it to make picture frames and he ran some pretty heavy tools on it, when I got it the blade would wobble. I replaced the bearings on the arbor and it cuts much smoother now, but when I shut the machine off, the blade runs smooth for a bit but then at a point when it slows down enough it suddenly vibrates a ton and makes a bunch of racket. I have a whole new arbor assembly for it, but before I install it, is there something else I should be concerned about with this saw?

[Garth Almgren]

You might try running it with the belts off and seeing if the vibration is isolated to the motor or if it is indeed in the arbor.

[Joe Jensen]

Garth has a great suggestion, if it's not the arbor it must be the motor bearings

[Martin Wasner]

Garth nailed it. Also, houhow old are the belts?

[Matt Day]

Vibration is caused by anything that moves.
Motor bearings
Belts
Pulleys
Arbor
Arbor flange washers
Blade

I would do as suggested and take the belts off. Turn on the motor and make sure that is smooth. Turn the shaft by hand and see if it feels good or rough like the bearings might be shot. A totally free spinning motor shaft his bed too, that means the grease is all gone. There should be some resistance but it should turn very smoothly. Check the belts for cracks, they may have a set to them which causes vibration. That can happen if the sauces for a long time. If everything checks out, and you still have vibration, I would be looking at the Arbor assembly. Before replacing the whole thing, put a dial indicator on it and see what kind of run out you have.

[Don Jarvie]

Also make sure the pulleys are aligned and there is no movement in the arbor housing. There is a set screw that holds the arbor in place. If this loosens it may cause the pulleys not to line up and could cause the vibration.

[Chuck Fischer]

What kind of cost is involved in replacing motor bearings, or is this like the type of thing that requires a motor replacement. I haven't checked the motor so I'm thinking that might be the issue. The previous owner ran really heavy molding cutters on this thing, it was pretty beat up when I got it.

[Joe Jensen]

replacing bearings if a normal service for a motor. That might run around $100? not sure as the ones I've had done were larger with larger and more expensive bearings.

[Chuck Fischer]

Where does one have an electric motor serviced?

[Rollie Meyers]

Where does one have an electric motor serviced?

If not doing it yourself, a motor shop.

[Matt Day]

It's a DIY job if you are mechanically inclined and have the tools (bearing pullers - I say plural bc sometimes a standard 3 jaw won't work and other types are needed like a bearing separator).
Using google maps search for "motor repair" to find a local shop. I agree with Joe, Plan on $100 or so I would think. Basically an hour job with parts (bearings).
Lots of vibration likely isn't the motor bearings, and I bet they'd be loud while running not just spinning down.

[Michael Dye]

Two things regarding previous posts. Make sure you put a dial indicator on the face of the arbor (where the blade makes contact) as well as the shaft itself. I helped a friend repair his 66, which included installing a new arbor assembly. Lo and behold, we had to remove the arbor and machine the washer face due to excessive runout. Second, the tools needed to remove the motor bearings can usually be sourced from your local auto parts store. I know AutoZone, PepBoys, and Chief all loan out bearing pullers. Good luck.

[CPeter James]

I really think that your "problem" is caused by the start capacitor cutting back in as the saw slows down. This is pretty common in PM66s. This is a know issue and there are several fixes, some work better than others. The one that seems to work best is to put a small resister across the capacitor terminals to bleed off the capacitor. Playing with the belt tension can reduce the effects, just not the cause.

http://www.temcoindustrialpower.com/...resistor_guide

You should be able to find a resistor at Radio Shack or similar stores.

CPeter

[Chuck Fischer]

I tightened the belts and that did help quite a bit, but yes, as the motor slows down there is a point at which it suddenly shakes a bit, with the belts tightened the shaking seems to be a lot less. I guess I didn't have those belts as tight as they need to be. I still think a motor refresh should be in the works as well as perhaps that resister mod. Thanks for the help guys.

[M Toupin]

I guess I didn't have those belts as tight as they need to be.

The belts should be just tight enough so they don't slip. Over tightening belts puts undo strain on both the arbor bearings and motor bearings and will cause premature failure.

Much cheaper in the long run to figure out whats the root cause and fix it rather than trying to cover up the symptoms.

Mike