Shopsmith Forums

Hello all;

I have been rebuilding my 1994 mark v. I have come across a little snag I need your help with. I finished putting the motor back in the case today and before I put the entire machine together, I decided to test the motor (I had a bearing replaced on the motor). I can turn the motor on, but it seems to be bogged down, then pops a breaker switch. I do have the 12" sanding disk on, if that makes a difference. When the motor DOES NOT have a belt on, it spins just fine, but as soon as the belt goes on, it bogs down, even when the belt is loose. What am I doing wrong

When you say "even when the belt is loose." How loose is loose?

I lubricated all the parts While putting it together. As far as the belt, when the sheeve is open all the way. Everything seems to spin properly when the motor is not connected.

[quote="vanmeter2r"]Hello all]Did you have a motor shop "replace a bearing" or did you have the "motor rebuilt"? If the motor was to have been rebuilt I would go back and ask if the motor was tested under load.

paulrussell wrote:When you say "even when the belt is loose." How loose is loose?

How CAN it be loose, if on the pulley???? The spring on the motor sheave should maintain tension so it NEVER becomes 'loose'.

Let us start somewhere closer to the 'beginning'.

1) Is the ss on a dedicated circuit? If not what else is 'on' it when attempting to start the ss?

2) What is the amperage capacity of the circuit to which it is connected?

3) Does the motor turn freely(by hand) when no belt attached?

4) Are you (manually using the sanding disc) placing the speed control in SLOW position before turning it on? This is when the motor sheaves are open, but the belt should NOT be 'loose'.

5) Are you removing the disc before turning it on?

6) Is the entire system relatively free to rotate even with the belt attached? There are some frictional/inertial forces to overcome, hence the word 'relatively'.

7) When you say 'bogged down', does it ever rotate, or just sorta hum and barely move if at all?


Why all these things are relevant!

The ss motor draws a very large starting surge current when starting(normally). If the circuit supplying the electrical source does not have sufficient amperage capacity then the overcurrent protection will kick in(tripped breaker). If the starting circuit in the motor is functioning correctly, the current surge is short and does not cause the breaker to trip.

The starting circuit consists of a centrifugal switch and a 'start' capacitor. The switch is made when rotational speed is low and connects the start capacitor to the 'start' winding of the motor.(actually it does something different, but that is 'beyond the scope of this 'post').

Assuming all the mechanics are NOT contributing to this 'problem' the most likely culprit is the start switch being open(assuming #7 above is accurate). If a bearing was replaced, which one? Was the start switch(and its actuating mechanism) reassembled properly???????

This be enough for this 'session'. Come back with answers/clues/observations!

Not you Paul, Vanmeter2!:D

I may start a little controversy here but I'll post my thoughts anyway.

I have owned my Shopsmith for about 30 years and it has always run on a 15 amp circuit. The only time it has kicked a breaker is when bearings inside the headstock went bad. I do make it a point to lube and blow out my machine on a regular basis.

I have never had to set my speed control to slow every time I start it up. I just leave the speed set to the last operation I used it for. When I get ready for a new operation, I turn on the machine at whatever speed the machine is set on and then adjust it for the new operation BEFORE adding any attachments or SPTs. I then shut the machine down, set up the operation and go to work.

I believe that if your Shopsmith is tuned and maintained properly it should start at any speed without tripping the breaker. I have operated this way for 30 years and never had a problem.

tdubnik wrote:I may start a little controversy here but I'll post my thoughts anyway.

I have owned my Shopsmith for about 30 years and it has always run on a 15 amp circuit. The only time it has kicked a breaker is when bearings inside the headstock went bad. I do make it a point to lube and blow out my machine on a regular basis.

I have never had to set my speed control to slow every time I start it up. I just leave the speed set to the last operation I used it for. When I get ready for a new operation, I turn on the machine at whatever speed the machine is set on and then adjust it for the new operation BEFORE adding any attachments or SPTs. I then shut the machine down, set up the operation and go to work.

I believe that if your Shopsmith is tuned and maintained properly it should start at any speed without tripping the breaker. I have operated this way for 30 years and never had a problem.

Hmmm about 30 yrs. That puts in in the late 70's, early 80's. That means a 1 1/8hp motor(I be assuming ya bought it new).

The larger motor starts up more quickly than the older 3/4hp motor(especially at higher speed settings). This reduces the time an overcurrent device 'sees' the overload. It also makes a difference what attachments/spt's may be installed.

I agree with you that if it works ok, it is not necessary to return to slow every off cycle. If however if it takes noticeable time to 'get up to speed' then turning it down makes sense.

This IMHO was needed historically since home wiring was less 'robust' years ago.(I know, I said this b4 quite recently in another thread).

I still do recommend turning it to slow prior to moving it or shutting down for the session.

What's an SPT?