Why not 10" grinding wheels?

[Steve Mathews]

John Keeton had an excellent idea (I think) to use my existing Baldor 6" grinder with 8" CBN wheels instead of getting another grinder. Since wheel guards aren't really necessary with CBN wheels this makes sense to me. But if there are advantages to larger wheels for our type of grinding why not use 10" wheels?

[Thom Sturgill]

One word - cost. The ultimate in that direction would be a flat grinding surface like a belt. Now if sorby could come up with CBN impregnated belts...

[Steve Mathews]

One word - cost. The ultimate in that direction would be a flat grinding surface like a belt. Now if sorby could come up with CBN impregnated belts...

Then why not use a carbide tool grinding wheel that allows grinding on the flat face? It shouldn't be too difficult to work up a jig or platform for it. Or better yet, why not just use a carbide tool grinder?

[Reed Gray]

I believe the Tormek type CBN wheels are 10 inch diameter. One problem would be having enough horse power to drive that size of wheel. The wet wheel type grinders turn very slowly, so not too much of a problem there. High speed 10 inch CBN wheel would be far more than most people could handle. Six, too little. !0, too big. 8 just right.

To grind carbide, you use diamond or another type of wheel, carborundum or some thing like that. Diamond does not go well with HSS, the carbon breaks down.

robo hippy

[Doug Ladendorf]

It can be done Steve. I have an older Baldor 10" grinder in the queue to restore and I'll probably put 10" CBN wheels on it as a major upgrade to my current Woodcraft grinder and stone wheels. I called Oneway about the use of 10" wheels with the Wolverine jig and they said it should work fine. If anything I might need a lift block added somewhere. I believe you have a 6" Baldor grinder. I would not add 10" wheels but I suspect it will be fine with 8" wheels. Note that the edge speed will be faster then with 6" wheels.

Doug

[Steve Mathews]

I believe the Tormek type CBN wheels are 10 inch diameter. One problem would be having enough horse power to drive that size of wheel. The wet wheel type grinders turn very slowly, so not too much of a problem there. High speed 10 inch CBN wheel would be far more than most people could handle. Six, too little. !0, too big. 8 just right.

To grind carbide, you use diamond or another type of wheel, carborundum or some thing like that. Diamond does not go well with HSS, the carbon breaks down.

robo hippy

Thanks Reed! That was helpful. After reading an article of yours on CBN wheels it seems that the 8" wheel on a 6" grinder is not such a good idea after all.

"...I have not heard of a grinder frying because the wheels were too heavy, so it may be nothing to worry about. In the same line of thought here, no, you should never run 8 inch wheels on a 6 inch grinder, ever...."

Here's a link to the full article. Excellent and informative read.http://www.robohippy.net/featured-article/

[Reed Gray]

Since I wrote that article, Ken Rizza of Woodturner's Wonders came out with aluminum hubbed CBN wheels. With the lighter weight, they would probably work fine on most 1/2 hp grinders. The power difference between my 8 inch Baldor and my 8 inch blue no name grinder from Woodcraft, both with '3/4' hp motors was as big as the weight difference, maybe not quite 2 to 1 in favor of the Baldor. A 6 inch Baldor might be able to handle 8 inch aluminum CBN wheels, but I don't really know. I prefer over built to under built.

robo hippy

[Geoff Whaling]

John Keeton had an excellent idea (I think) to use my existing Baldor 6" grinder with 8" CBN wheels instead of getting another grinder. Since wheel guards aren't really necessary with CBN wheels this makes sense to me. But if there are advantages to larger wheels for our type of grinding why not use 10" wheels?

Steve, wheel diameter choice affects the grind profile on the tool. It is perhaps most noticeable on skew chisels with a narrow included angle i.e. a wide bevel face. A 6” wheel will create a deeper concave face than an 8” wheel with a 10” creating the flattest face. That face profile affects how a skew chisel performs “rubbing the bevel”, perhaps not such an issue with bowl gouges though.

Wheel diameter selection is dependent upon user preference, however the grinders motor also has to be capable of delivering the torque and power at constant speed under normal load for it to be functional, and the grinder / wheel combination must be compatible.

As a safety note,

Wheel guards are fitted to grinders for a couple of reasons mostly to prevent unintended contact with moving parts & entanglement; to confine hot sparks and also to confine fragments of wheels and tools.

With traditional grinders (hi-speed) the hazard of flying particles is present, and the risk still high and even higher if the grinder is unguarded with no safety eye screen/s fitted. CBN wheels do not eliminate that hazard, they may minimize it slightly.

CBN wheels do present a lower risk profile than bonded wheels. The only hazard with significantly lower risk is that from wheel explosion due to the current manufacturing quality - still possible though. The possibility of larger bits of “modern tools” coming off the grinder is also relatively low but that hugely depends upon quality control by the manufacturer for both the tool & wheel, and in service handling.

https://www.osha.gov/SLTC/machineguarding/new-grinder-checklist.html

In most jurisdictions an unguarded wheel on a grinder; guards that exceed maximum permitted openings etc; or mismatched grinder / wheel specifications would result in an infringement notice at best in a workplace.