Seeking grinder advice

[Steve Busey]

I saw the thread about diamond grinder wheels and rather than hijack that thread, will start another. I'm hunting for a bench grinder (used is fine) to sharpen turning tools. I'll likely try and build a poor man's Wolverine jig, but a few questions came up: + what size wheels (6" or 8")? + what speed should it run? + and what grits do you use? Thanks in advance!

[Tony De Masi]

Steve,

I use a slow speed, 1725 rpm, Woodcraft grinder which you can get quite often on sale for around $79, using 8" wheels. For the wheels mine is set up with a 60 grit for shaping and a 120 grit for sharpening and touch up.

Tony

[Neal Addy]

I know there are strong feelings out there about grinder specs but frankly I don't think size or speed matters very much. 6" or 8" will do fine. Some say that 6" puts a more concave bevel on your tools but honestly the difference in it and 8" is not enough to haggle over.

Same goes for speed. The Wolverine instructions recommend 3450 RPM but I've never understood why. My slow-speed grinder turns at 1725 RPM and I doubt very much you could get a better grind from high-speed. The only advantage I can see to slow-speed is that your tools won't heat quite as quickly, but even that is negligible (and arguable).

The main factor for HSS turning tools is the wheel. You want as much real estate (i.e. grinding surface) as you can get. This is where an 8" wheel does have a slight advantage. You'll be more likely to find a 1" wide wheel in the 8" size than the 6" size. The widest 6" wheel I've come across is 3/4". There may be 1" out there but they're harder to find.

Most folks prefer Aluminum Oxide (or better) wheels for HSS steel. Doesn't matter if it's white, pink, gray, or polka-dots as long as it is AO (or SG). Norton makes AO, SG, or what they call 3X wheels. All of these are good and mostly depend on your budget.

The last factor I'll mention is to make sure the grinder base doesn't have "shoulders" (i.e. flanges) that extend so wide they sit under the wheels. Your Wolverine (or DIY) guide needs to be positioned directly under the wheels and about 6-1/2" from wheel center to your base platform.

Like Tony, I use the Woodcraft 8" slow-speed grinder. It comes with two pretty decent AO wheels making it a great bang-for-the-buck. It also works beautifully with a Wolverine.

[Jim Becker]

You don't need an expensive grinder for the job. Just decent quality. I do recommend you go to 8" as the larger wheels leave less of a hollow grind and are 1" wide. If you can score a ~1750 speed grinder, so much the better, but with HHS tooling, the 3600 rpm grinders are just fine. (I use the higher speed unit) You'll take off more metal at first as you are learning, but once you develop a light touch, there will be no difference.

Someone mentioned the Norton 3x wheels. I'm using those presently and like them. Hartville Tool also carries them in my preferred 60 and 100 grits. (I don't like 120 grit wheels...more heat and no major advantage in keen-ness when you are going to the grinder frequently as you will be for turning. IMHO, of course...

[Paul Engle]

I use a 6 in delta and a 2 1/2 x 4 inch cup wheel 120 grt ( 3250 rpm) and 1x 6 in 80 grt sil carbid for carbide at 3250 rpm, works just fine ,3/4 x 6 ,36 grt for rough shape.I also have a delta wet system 400 rpm for the wet and 3250rpm for the 4 inch cup and home made jig for my bowl gouge using the vari grind holder. Just a light touch, works great.

[Steve Busey]

Thanks for the great advice. I knew you guys were sharp!