Diamond Bench Grinder Wheels

[James Baldwin]

Hi, I'm thinking about upgrading my 8" bench grinder wheels to a diamond wheels and was wondering what would be the best all around choice for two wheels. Thanks, Jim

[Robert Hayward]

You say diamond, but do you really mean CBN? Cubic boron Nitride?

[Reed Gray]

Woodcraft used to have some diamond matrix wheels that was bonded to an aluminum hub. One turner has them and loves them. The problem with diamond is that even the slow speed grinders run too fast for them, and speed = heat, and heat destroys diamonds. There are diamond wheels for the Tormek and other wet wheel sharpening systems. Because of the water bath and very slow speed, they might be able to last pretty much forever. I think they come in 320, 600, and 1200 grits. I think the Tradesman Grinder form up in Canada also makes diamond wheels. Their grinder has a variable speed motor and can run slow enough for heat not to be a problem.

Most popular in the woodtruning workd are the CBN wheels, cubic boron nitride. Diamond is just slightly harder than boron. They come in grits from 60, up to 1200. They generally are metal wheels. I think most are 1 1/2 inch wide wheels, which I prefer. The CBN is nickel plated onto a metal hub, some steel ones and some aluminum ones. Don't know if plastic ones are made any more or not. They are made for grinding 'hardened' steel, which would include all turning tools, except the old carbon steel ones which can build up on the wheel rather than grind clean. Bench chisels and an axe are fine on the CBN wheels. They come bubble and spin balanced so they run true. They will never blow up. If you get one, get a 180 grit since it will handle 90% of all the sharpening you will do in your shop. For a second wheel, I would suggest a 600 grit. 320 grit isn't much of a step up. Just about all sharpening supply places carry them now. Mine are mostly D Way. Woodturner's Wonders also sells them.

robo hippy

[James Baldwin]

Yes I did mean CNB wheels. My grinder uses 1" X 8" wheels. I don't know if the 1 1/2" wheels will fit . If the hub is the same thickness as the 1" wheel(recessed) then they would work. Jim

[Robert Hayward]

The hubs are usually sized to fit a normal grinder shaft. My recommendation would be to choose a supplier/brand and then call them for the hub width dimensions. That would guarantee a proper fit.

[Reed Gray]

You can also tell them what type of grinder you have. They should be familiar with all of them.

robo hippy

[James Baldwin]

I bought it from Woodcrafters originally. What I'm going to do is pull one of the grinding wheels put the flanges and nut back on and measure the distance between them. Jim

[Dave VanDewerker]

You will need to remove the outside wheel guards for the 1-1/2 CBN wheels to fit. I bought the 180 & 600 combo pack from here (https://woodturnerswonders.com/). Also bought the self aligning washers. I use the 180 for rough work, ie regrinding a bevel or grinding a new bevel. I use the 600 for touch up and maintaining the bevel.

[John K Jordan]

Hi, I'm thinking about upgrading my 8" bench grinder wheels to a diamond wheels and was wondering what would be the best all around choice for two wheels. Thanks, Jim

“Best choice” may depend on how you work and what you turn. On a half speed 8” bench grinder I use a 60-grit CBN wheel for shaping tools and a 600-grit for sharpening most tools. (I use a 10” 1200-grit CBN wheel on a Tormek for my spindle gouges) For some, a 180-grit wheel is just right for sharpening their bowl gouges, too coarse for my skews, NRS, and others IMO.

Unlike standard wheels that can be dressed if they are not perfectly true CBN wheels have to be perfect. If any runout it’s probably from the nut. I use the inexpensive spherical washer sets from Woodturners Wonders on every CBN wheel, for myself and for those I set up for others. Also, all my CBN wheels have corners rather than rounded edges and have 1” of grit down the flat sides - I find these necessary to shape and sharpen certain turning tools I make.

(For those who may not know, don’t use diamond wheels to grind steel. The carbon in the steel can react with and degrade the diamonds.)

JKJ

[James Baldwin]

Well I pulled the current wheels and measured the distance between the washers with the nut screwed on and can only use a 1 inch thick wheel maybe. I'm going to contact Woodturners Wonders and discuss my options with them. Jim

[Reed Gray]

One problem I had with fitting the 1 1/2 inch wide wheels on my 1 hp Rikon grinders was the indents or what ever you want to call them, the punched and threaded holes in the wheel guard on the grinder side of the guard. They may need to be ground or pounded down/off. With my Baldor grinders, I had to have a machine shop make some 5/8 inch thick washers to space the grinder side of the wheel far enough out so the nut would tighten against the wheel.

I haven't tried it yet, but this may work instead of the helical (one concave, one convex) washers. The steel for these nuts is pretty soft, and you could chuck them up and 'true' them up a bit. Standard M2 hss should be up to the job. The standard nuts that come with the grinders are not precision machined.

Oh, if you use an 'insert' to account for different axle diameters, DON'T use the plastic ones. They are junk!

robo hippy

[John K Jordan]

Well I pulled the current wheels and measured the distance between the washers with the nut screwed on and can only use a 1 inch thick wheel maybe. I'm going to contact Woodturners Wonders and discuss my options with them. Jim

One thing Ken Rizza at Woodturners Wonders will do for you is sell you a bench grinder already set up with two CBN wheels of your choice. A friend did that and had the ready-to-use sharpening station in his hands in a week or so. No measuring, adapting, aligning - just plug it in an start sharpening. He buys these grinders at a good price without the guards and things that have to be removed anyway.

If you visit a woodturning symposium where he’s a vendor you can usually leave with one ready to use.

[John Keeton]

+1 on dealing with Ken Rizza! I have a 180 grit CBN wheel that is at least 10 years old. A couple years ago I bought a 1hp Rikon grinder from Ken along with a 600 grit CBN wheel. Great setup! I use the 600 wheel almost exclusively. Ken if great to do business with.

[James Baldwin]

An update, My new CBN wheels got here today. I orderd a 1" X 180 grit and a 1 1/2" X 600 grit from Woodtuners Wonders. Got them installed and did a quick touch up on one of my bowl gouges with the 600 grit. I'm going to get spoiled. Jim

[John K Jordan]

An update, My new CBN wheels got here today. I orderd a 1" X 180 grit and a 1 1/2" X 600 grit from Woodtuners Wonders. Got them installed and did a quick touch up on one of my bowl gouges with the 600 grit. I'm going to get spoiled. Jim


Great! I trust you’ll get as spoiled as I am. I was a CBN holdout even when some of the woodturning movers and shakers I trusted were switching to CBN. Once I got started I couldn’t go back! I bought and tried a bunch of grits in several wheel styles before I settled on what I use now.

I’d add two cautions, if not already mentioned. One, the CBN wheels seem to produce more extremely fine steel “dust” that will float in the air, more than I saw with conventional grinding wheels. I have magnets stuck to far side of a bandsaw over 10’ away and find them coated with fine black dust that floated across the room. With a bright task light in an otherwise darkened room I can see the particles floating in the air when sharpening with my 600 grit wheel. Good time to wear a dust mask or respirator!

Another caution - if it accumulates, the fine dust can be easily set on fire. I keep a strong magnet just under and behind the bottom of the wheel which catches a lot of the steel dust. One time I let it accumulate until the magnet was hidden by a fuzzy ball of black. After one sharpening session I by chance notice this fuzzy ball was glowing orange inside - a spark from the CBN wheel apparently ignited the steel! Fortunately I was able to grab the magnet and take the burning steel outside.

Since unlike a conventional bench grinder wheel the sparks from a 600-grit CBN wheel are sparse and very fine, I assuming it doesn’t take much to ignite the steel. Now I clean the magnet occasionally. (Keep it in a plastic bag and take it out to release all the fine steel dust.)

If not familiar with how well steel burns try holding a flame to a wad of 0000 Liberon steel wool. (do this outside) For even more fun, saturate any steel wool with powdered aluminum. (do this outside too) For even more fun, use powdered magnesium. (this is how I spent my youth - don’t ask for details) Some such power mixtures are used in pyrotechnics. A thermite reaction can get hot enough to melt steel. Thermite was once used to weld railroad rails. Moral of the story: use caution around powdered metals in the shop!

https://en.wikipedia.org/wiki/Thermite

JKJ