Odd bench grinder behavior

[Randy Reece]

I acquired a Western Hawk, Model 6803167, variable speed, 8 inch bench grinder (used). It's crap but that is beside the point. I'm ignorant when it comes to electrical. After I have been grinding plane irons on it for a short time the motor will appear to stop putting out power which causes the speed of the wheel to drop. Then, the power kicks in again and the wheel speeds up only to cut out again. This on/off cycle increases between events until the grinder is jumping around. The only way I have been able to deal with it is to shut it off for a while and the motor cools down. What causes this behavior? It has a 4.2 amp, 120 V motor and is, of course, Chinese made. It was originally sold by Orchard Supply Hardware (OSH) for around $100 a couple of years ago I am told. Is there a speed regulator that turns on and off automatically? The wheel is rated for 2000-3450 or so RPM and I usually try to grind at around 2000 RPM to avoid burning the plane irons. I am totally puzzled at his behavior but then again I have never had any training on motors in my 69 year life. I assume that if I am bearing down too hard on the wheel the motor would just slow down till it burned up. Very odd. Any suggestions as to cause? Secondly, I would like to get a better 8" bench grinder. Has anyone had experience with the new Steel City model sold by Highland Woodworking or can suggest another good machine. Baldor is too steep for me but are there any good bench grinders between $200-$300?

[Lee Schierer]

It sounds like the thermal overload protection is malfunctioning. They are usually buried in the windings, so there is no chance of a repair.

[Todd Willhoit]

+1 on what Lee said.

A few other things to consider: How long is the power cord? Are you by chance using a small-gauge extension cord between the grinder and the receptacle? Have you checked the connections in the motor terminal box to ensure they make good contact?

[Pat Barry]

You mentioned it is a variable speed motor. From your description I'd be thinking the problem lies inside that controller. It could be the speed controller has an internal malfunction (bad wire connection, broken wire, maybe one of the internal electrical components). Lets say you run the thing wide open. Let it just sit and run. Does it start to act up after a while? If it runs OK at full speed and has trouble when you try to whoa it down then I think its the controller thats bad

[Reinis Kanders]

I am pretty happy with my steel city 8 inch slow grinder. I use it with CBN, but it also seemed to be ok with the stock wheels.

[Duane Meadows]

I agree with Pat. Electronic speed controller!. If you want slower speed I'd recommend an 1800 RPM fixed speed unit. You will be much happier. Steel City should be fine.

[Randy Reece]

I use the supplied cord directly to the wall outlet. It only cuts out after use. The grinder vibrates enough that a loose connection would be affected without me grinding anything.

[Randy Reece]

I have run it and just sat back and watched. No cutting out occurred. The speed control dial works like a rheostat so I just dial in the speed I want. When it cuts out it can happen at any speed.

[Randy Reece]

Fine Woodworking (I think) had a review of 8" grinders last year and they weren't really happy with any of them. They only looked at grinders below $200 or $300. The review came out before the Steel City Model that Highland Woodworking sells. I would up to $300 for a decent grinder if I could find one. I'm using Norton friable (sp?) wheels now with Veritas tool rest. Fine Woodworking was really down on the tool rests, stamped flanges, etc. I never heard of CBN wheels until a couple of days ago. They seem amazing. The Norton wheels I have came with plastic inserts that caused horrible wobbling. Who do you recommend for CBN wheels? At my age and the pace I am woodworking, I would never have to replace CBN wheels.:)

[Randy Reece]

Thanks. I will take a close look at the Steel City model.

[Randy Reece]

Thankfully, I don't have much money tied up in this crappy grinder. I'll drop it in the garbage.