Shaper Shutting Down by Itself

A woodworker gets help troubleshooting a shaper that cuts out for no obvious reason. July 29, 2012

I have a SCMI T-40 (1998) shaper that has started to cut off on its own. We don't use it every day, but we had been running it a lot that particular day when it just started to shut off by itself. It would start without any hiccups but would only run for 5 minutes or so. Luckily, we were finishing a couple of raised panels, so it didn't really mess us up.

The only thing to report was that the motor appeared to be pretty hot. Otherwise, it has been lightly used over its life. Any thoughts?

Forum Responses
(Solid Wood Machining Forum)
From contributor D:
It could be your starting capacitor. Look to see if it is bad.

From contributor B:
My SCMI T-110 gave me fits for a couple years at one point. It would cut off for no apparent reason and we'd have to push the reset button on the front of the machine before it would restart.

I finally traced the problem to a failed overload sensor in the motor circuit. It looks much like a 3 pole contactor (relay) but has a dial on the face that is set to match the motor current draw.

Since your motor is getting hot, my guess is that the overload sensor is just doing its job as it should. I would check to see why the motor is overheating. First remove the drive belt and run the motor with no spindle load to see if it cuts off. If not, then check your spindle bearings. If so, then check the motor bearings. If all else fails, you may have to pull the motor and have it checked out.

From contributor J:
We used to have a T40N that did this. I think it was a dirty contact in the overload circuit. If I remember correctly, removing it, blowing it out with compressed air, and spraying it out with contact cleaner solved the problem.

From the original questioner:
Where is this located? The shaper is one of the few machines I've not taken apart.

From contributor J:
Basically - clean out the start/stop/reset switch.

From contributor B:
After cleaning out the START/STOP switch and box, follow the wires back to where they come from. They should lead you right to the contactor and overload protector. The overload may or may not be mounted directly to the bottom of the contactor.

Some of these wires are live even when the machine is off, so be sure to disconnect power… as I'm sure you were planning on doing.