Motor or belt problem

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jdharris
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Motor or belt problem

Post by jdharris »

After not using my Shopsmith Mark V much in the past couple of years I have been trying to use it for some small projects over the last 2 weeks. It is causing the circuit breaker to throw frequently on startup. The problem was getting worse so I oiled it. This seemed to help some but it still throws the breaker when it is not set to slow speed when it starts up. At higher speeds it starts slow and then struggles as it is building up speed. The belt looks to be OK. I would appreciate any suggestions.
JD
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dusty
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Motor or Belt Problem

Post by dusty »

Need a bit more information:

1) Is the Shopsmith on a circuit by itself?

2) Is the circuit a 20 amp. circuit?

3) If the SS is set at a low speed, does it come on normally?

4) Are you using an extension cord? If yes, what gauge wire and how long?

5) Are you using a circuit that has worked normally in the past?

6) Can you measure line voltage to ascertain that it is 115 volts?

7) How cold is it in your shop? The manual recommends > 55 degrees.
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jdharris
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Follow-up motor or belt problem

Post by jdharris »

Thanks for your response. The shopsmith is on a 15amp circuit with a GFI. I am currently using the shopsmith in my garage while I am working to complete my shop in the house we just moved into. (Sometimes it is the GFI that trips and sometimes it is the breaker.) The circuit is not dedicated but there are no other devices plugged into garage outlets. The voltage is 118 volts. When I start it at slow speed it starts normally with no problems. If I then crank up the speed it will blow the breaker by the time I reach high speed. If I start it at high speed then it starts slow and builds up speed usually blowing the breaker at about the time it reaches the high speed. The shopsmith during my testing today was plugged directly into an outlet. I did try pluggin it into a 20amp outlet but I had to use a 50 foot 12 gauge extension cord and I got the same result. JD
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dusty
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Motor or Belt Problem

Post by dusty »

Unless you know the age/condition of the breakers (especially the GFI) I would consider replacing the breakers; but that is easy for me to say, I don't have to pay for them.

The test with the long extension cord indicates to me that you do NOT have power source problems. A 20' 12ga extension cord is right at the maximum recommended but I think the test indicates the circuits and the source are NOT your problem.

I assume the only load is your table saw and you said it runs OK at low speed.
You also said that you recently lubricated and I assume that was done per the manual. Did you check or adjust belt tension - particularly the poly-v. That belt, if too tight could cause an overload that would trip the breakers but I fear that is wishful thinking.

You have sort of led me to suspect the motor (motor bearings). Unfortunately the most expensive guess one could take. I would seriously consider pulling out the motor an having it "checked" by a good motor shop.

If your SS sat unused for an extended time, you might turn it on at low speed with no load and just let it run for awhile. My thought being that the drive line might be a little tight from sitting (especially if it is cold where your SS is at). Ten to fifteen minutes would be all I would wait.

The rest of the forum has been awfully quiet but I suspect you will get inputs very soon. Keep us posted on your progress and especially the final fix. This is how we all learn!

Wishing you a rapid return to "making sawdust".

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Nick
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Post by Nick »

JD, 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,
jdharris
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Motor or belt problem follow-up

Post by jdharris »

Thanks for the responses. I tried Dusty's suggestion of letting the shopsmith run at slow speed for 15 minutes. I first oiled it again. After letting it set for a few minutes I was able to rip several one inch boards without tripping the breaker. I'll try some other operations over the next few days and see how it does. JD
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