Get your motor running...

Well, it's been a day of trying to do that. In the past month my bench grinder and my 1" x 30" belt sander both quit working.

The belt sander is from HF and I've had it about 5 years now. It was working pretty well and had been running for a good 30 minutes, then after shutting off it would only hum when trying to turn on again...typically the tail tail sign of a bad capacitor

Today I looked up the wiring diagram on the HF site and found indeed it had a capacitor.


Based on the size of the motor and the fact it had a larger than needed box for the switch, I assumed the capacitor was in the box as well.


Using my digital ohm meter I set it to the 1k setting. I touch one probe on each wire for a few seconds, then reversed the probes/wires. I didn't get a reading. Typically you should see at least some reading when you reverse the probes. So between the hum of the motor and no reading change on the capacitor, it's probably bad.


A quick google, I wasn't able to find an exact match without shipping it from hong kong, but grainger had a similar one in stock for $6 that I'll be picking up this week. Just thought I'd document this little fix as I'm sure some of you have ran into this same issue before. One tip, the voltage rating on the new capacitor just needs to be as much or higher than what your tool runs, but the microfarad rating needs to be within tolerance. So though I took a 250 volt cap out, I'm replacing it with a 125 volt cap with the same microfarad rating.


So, on to the grinder. The I had just finished sharpening the blades on my riding motor, shut it off and decided to sharpen the push mower blade as well. As I turned on the grinder, sparks and smoke shot out both sides of the vent holes. Well, it looks like some of the insulation overheated and shorted the windings, the yellow insulation look to be chewed up by a mouse, but they are actually melted through.


Needless to say, this grinder is about 30 years old, I remember my dad buying it. The bearings are starting to rattle and it's needing new wheels anyway, so I'll be picking up a new grinder soon. Any recommendations for a new one?

You gotta get those pesky mice Darren.

Hey you ever played tbe fool with a nice large electrolytic cap.

My first day at work in a lab one of the "old hands" charged up one and tossed it to me saying put it on the shelf.

As to grinder i like my delta 8" variable speed.

But just dont get burnt like i nearly did thinking i was picking up a second grinder for a real cheap price. It was from a local auto store that is more like the Canadian version of HF.
The motor was fine, it was the shaft and way the wheel was attached to the shaft. The delta has a custom split type washer nut that allows for hand tightening and the shaft is a standard size i think mine is 5/8.

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I was fortunate, one of my neighbors growing up was an old navy electronics tech. He taught us early what they were, he used to keep a charged one in his car as a tazer as he did late night calls to the downtown hospitals.

Got the new cap installed last night and it's running like a champ.

And away we go!

I had an exciting time once when the caps on my DC decided to catch fire... Replaced them and all was right as rain again.

Champ may have been an overstatement, considering what it is. It's at least running. I may order another that is closer in tolerance, seems to be running a little slower than it did before, but no more than I actually use it, it should suffice.

I can't help with the grinder except to say Baldor if you have deep pockets. I let a used baldor grinder get away before I new anything about quality. Actually he was going to give it to me and I told him I didn't need it. One of my many you big dummy moments when I look back.

I've got a delta 8" variable speed that's ok. The cap went out on it and I took it to a local motor shop. The guy that runs it looks like he's 90. The shops been there as long as I can remember. When I handed him the capacitor and told him what it was from he spouted a few curse words and mumbled something about Chinese crap. He said that wasn't even the right size. He said they must stick whatever they have on whatever they're making. He went in back and came out handed me one and said here this will fix it and it's made in America. I took it from his reaction he didn't much like Chinese stuff!

John Daugherty said:

I can't help with the grinder except to say Baldor if you have deep pockets. I let a used baldor grinder get away before I new anything about quality. Actually he was going to give it to me and I told him I didn't need it. One of my many you big dummy moments when I look back.

I've got a delta 8" variable speed that's ok. The cap went out on it and I took it to a local motor shop. The guy that runs it looks like he's 90. The shops been there as long as I can remember. When I handed him the capacitor and told him what it was from he spouted a few curse words and mumbled something about Chinese crap. He said that wasn't even the right size. He said they must stick whatever they have on whatever they're making. He went in back and came out handed me one and said here this will fix it and it's made in America. I took it from his reaction he didn't much like Chinese stuff!

Click to expand...

I may use it for an experiment, been reading on the caps and seems it can make a difference on HP. The variance of the microfarads will change the timing/pulses sent to the coils. Of course to many and too little can cause variance in the current flow to the coils and burn them up faster.