Motor problem

[jmhaz]

Hello everyone;

My father-in-law gave me his 1950s-era Shopsmith some years ago. The motor was showing signs of age, so a couple of years ago I bought a used headstock with the more powerful motor. I plugged it in at the time and it seemed to run fine, so I stored it. Today the old motor finally died, so I replaced the headstock with the "new" one. However, when I turn it on (on low speed), the motor begins to speed up, then something inside clicks and it slows down, then it speeds up again, then clicks and slows down, and finally the breaker on the circuit pops.

Can anyone tell me what might be happening, and what I can do about it? Thanks very much for any suggestions.

[Bruce]

I'm not a motor person, but it seems the click you hear may be some kind of relay. I would call Shopsmith.

[dusty]

I posted to this thread yesterday but I must have done something wrong. I'll try again.

I think that you should eliminate the motor as your cause first. To do this, I would test the motor with no mechanical load (take the drive belt off and run the motor). If it comes up to speed without popping a breaker, you will have a fair indication that the motor is either good or reparable. I recommend that you have the motor checked by a motor shop before doing anything else.

The headstock has been in storage. Lubricants stiffen with idle age. This would cause an increase in mechanical load. There is a very slight chance that this could be your problem.

While you have the headstock open, give it a real good cleaning and before you put it back in service, lubricate it. Check all of the belts, be critical. Once the headstock is properly serviced, it will sure you well for many years.
___________________
Making Sawdust Safely

[dusty]

I was looking back through some previous posts and found this one that I believe deals with the same problem.

Hope this helps!

The symptoms you report suggest one of two possible causes.

(1) The "motor cap" or capacitor in the induction motor that powers your Shopsmith has gone bad. This capacitor stores electrical energy and releases it when you first turn on the machine. It sends a jolt of get-up-and-go surging through the copper veins of motor that helps it get up to speed, sort of like a cup of electric coffee. If the coffee pot is empty, you may need to rebuild or replace the motor.

(2) The bearings have gone bad. It's difficult to imagine that a bearing can just "go bad" if your machine sits in the garage and does nothing, but that in fact does happen. I've rebuilt antique bicycles and other machines whose bearings destroyed themselves while they sat in a dusty corner of a garage or barn. The lubrication in the bearings dries up, moisture condenses on the balls and rollers, and rust pits develop where the balls and rollers contact the races. With each passing change in temperature and relative humidity, these pits grow deeper until finally when someone moves the machine the bearings grind rather than roll.

This can happen very quickly on woodworking machines. We often put our Shopsmiths to bed with a fine coat of sawdust on most of the surfaces inside the headstock, including the bearings. This helps to wick out the lubrication and hastens the damage done by condensation and corrosion. When, after a few months or years, you attempt to use the Shopsmith again, the motor has to work harder to overcome the resistance created by the damaged bearings. It tries to suck more juice out of the electrical socket to provide this energy and pow! -- the circuit blows.

The fact that your breaker pops even when you make a "soft start," setting the machine on low speed and running it up to high speed, seems to suggest that the problem is #2 -- your bearings have dried out and corroded. Luibrication will partially solve the problem as you've already discovered, but a complete cure may require that you rebuild the headstock.

With all good wishes,
__________________
Nick Engler, Director
Shopsmith National Woodworking Academy

[jmhaz]

Thanks very much for the specific and practical suggestions. I will pull the unit apart and start checking each component, beginning with the unloaded motor. I'll report back when I figure it out.

[rallen]

Just FYI...

I recently dissassembled my 61 motor to replace bearings, and then when I went to buy the bearings at a local motor shop (quite inexpensive...maybe $3 each?) decided to have them clean the motor and install the bearings.

The entire cost was $50, and I think it was worth it to have them wash the motor in cleaner, bake it to dry it out, clean the points up on the starter relay, test everything, and give it back to me. It now makes a wonderful hummming sound. My capacitor, however, did not require replacing. They told me I should be in good shape for the next 40 years.

Those motors will last forever if maintained; heat is the killer. If you do the job yourself, make sure you get all the sawdust out that you can.

Robert

[Ed in Tampa]

Hello everyone;

My father-in-law gave me his 1950s-era Shopsmith some years ago. The motor was showing signs of age, so a couple of years ago I bought a used headstock with the more powerful motor. I plugged it in at the time and it seemed to run fine, so I stored it. Today the old motor finally died, so I replaced the headstock with the "new" one. However, when I turn it on (on low speed), the motor begins to speed up, then something inside clicks and it slows down, then it speeds up again, then clicks and slows down, and finally the breaker on the circuit pops.

Can anyone tell me what might be happening, and what I can do about it? Thanks very much for any suggestions.

I think the key to this problem is the "CLICK" it sounds like the starting relay/points are closing that causes a problem. I don't know how the Shopsmith motor is wired but many motors have the start winding normally closed and then as the motor gets up to speed the centrifical force causes a relay to kick in the run windings. Perhaps the contacts are dirty and instead of making contact they don't. The motor will slow then the start winding will kick back in and we repeat until the start windings get hot enough to blow the breaker.
Ed

[dusty]

This is somewhat off the subject but can anyone out there explain to me just how the Shopsmith motor works at startup?

I tried the Emerson web site but they will not disclose technical information about the Shopsmith motor (and others to include Sears, Delta and Porter Cable).

Is there a "starter relay" or "starter capacitor"?

On the motor label there is a specification "S.F.A. 13.2 amp"; what is SFA?
___________________
Making Sawdust Safely