Grinder Wheels Questions

[Chris Stolicky]

I know there have been many discussions about grinder wheels, and I have searched many of them....

The quick question is - Does anyone know what the equivalent hardness level is for the 120 grit wheel that comes on the WC slow speed grinder? i.e. I, K, something else? I am posting this in the Turner's forum because mostly what I sharpen these days are various turning tools.

Here is my situation...
Like many of us, I have accumulated over time many means of sharpening my tools. I currently have a couple of setups:
- A delta variable speed grinder - standard rough gray wheel, and a Norton 3X 80 grit, K hardness wheel (with PSI sharpening jigs).
- A WC slow speed grinder with the 60 grit and 120 grit that came with it (w/ wolverine jigs).
- I also have a Tormek (bought it pre-owned).

By the way - I think both the WC grinder and wolverine jigs are much nicer than the delta grinder and PSI jigs. The Tormek is great but has its relative strengths and weaknesses. Sorry for the tangent....

Here is the deal....
I recently had a bit of a snafu and took a chunk out of the 120 grit wheel on the WC grinder. Lesson learned, pay attention and don't stand on slippery floors when you dragged in snow! Anyway, I don't trust the wheel any more and would lose a lot of the wheel if I tried to true it, if even possible. So, I am going to replace it. I have found that I like the hardness (softness?) of this wheel, and the relative grit. The Norton 3X 80 grit K is a nice wheel, but I find (w/ my current level of ability) it cuts the metal a little too fast for my liking. I was originally leaning towards one of the 150 Norton AO wheels, but decided it might be a little too extreme.

So, I know that some people think the Norton 3X I hardness wheels are a bit soft, but I am wondering if they are anything like what the WC grinder comes with. If that is the case, there both a 100 grit and a 120 grit option.

Experience with these wheels and related comments would be greatly appreciated.

Thanks.

[Richard Madison]

Chris, From what folks have posted here in past, it seems that J and K hardness are about right, and I is indeed too soft. For strictly sharpening (no reshaping or other grinding) I would choose a 120 grit, but opinions vary widely on this subject.

[Rob Cunningham]

Chris,
I can't answer your question but would STRONGLY suggest that you remove the chipped wheel from your grinder right away and trash it. There could be hairline cracks in the wheel which would cause it to explode when running.

[Leo Van Der Loo]

I know there have been many discussions about grinder wheels, and I have searched many of them....

The quick question is - Does anyone know what the equivalent hardness level is for the 120 grit wheel that comes on the WC slow speed grinder? i.e. I, K, something else? I am posting this in the Turner's forum because mostly what I sharpen these days are various turning tools.

Here is my situation...
Like many of us, I have accumulated over time many means of sharpening my tools. I currently have a couple of setups:
- A delta variable speed grinder - standard rough gray wheel, and a Norton 3X 80 grit, K hardness wheel (with PSI sharpening jigs).
- A WC slow speed grinder with the 60 grit and 120 grit that came with it (w/ wolverine jigs).
- I also have a Tormek (bought it pre-owned).

By the way - I think both the WC grinder and wolverine jigs are much nicer than the delta grinder and PSI jigs. The Tormek is great but has its relative strengths and weaknesses. Sorry for the tangent....

Here is the deal....
I recently had a bit of a snafu and took a chunk out of the 120 grit wheel on the WC grinder. Lesson learned, pay attention and don't stand on slippery floors when you dragged in snow! Anyway, I don't trust the wheel any more and would lose a lot of the wheel if I tried to true it, if even possible. So, I am going to replace it. I have found that I like the hardness (softness?) of this wheel, and the relative grit. The Norton 3X 80 grit K is a nice wheel, but I find (w/ my current level of ability) it cuts the metal a little too fast for my liking. I was originally leaning towards one of the 150 Norton AO wheels, but decided it might be a little too extreme.

So, I know that some people think the Norton 3X I hardness wheels are a bit soft, but I am wondering if they are anything like what the WC grinder comes with. If that is the case, there both a 100 grit and a 120 grit option.

Experience with these wheels and related comments would be greatly appreciated.

Thanks.

I would go for the 120 grit in K hardness for sharpening, you do have other options if doing anything else like shaping the tools, but you will have to keep the wheel dressed to keep it working well, more so than with coarser grits

[Mauricio Ulloa]

I use 100 grit in both sides of the grinder

[Jamie Straw]

The problem with the stock wheels that come with (or for) the Woodcraft slow-speed grinder is how unbalanced and un-true they are, IMHO. Norton wheels have a reputation for being much better in this regard.

Trick seems to be finding a 120-grit 3x in K hardness.

[Mike Spanbauer]

When I received my woodcraft slow speed grinder, one was really good and other was really, really bad. I didn't feel like picking up the oneway balancing set, so I took the wheel out, grabbed an appropriately sized deep well socket (such that it just barely fit inside the stone) and whacked the sleeve until it sat perfectly true. After that it spun as well as I'd expect on an import grinder. Some day I'll have an 8" Baldor in the shop... but, that's a ways off and this will work just fine until that point.

mike

[Richard Madison]

Good job Mike. That's what I would have done too. Not always necessary to buy something to solve a problem.

[Paul Ray Moore]

Mike,
Don't mean to hijack this post but when you say you use a deep well socket, do you mean you put the socket over the spindle and hit the center of the wheel while it is on the grinder or are you taking the wheel off and hitting the center on a flat surface. I've got some wobble on my grinder and I thought I might try your method. I'm using the factory stones now but have a Norton stone on order hoping that will fix the wobble when it comes in.

[Bob Bergstrom]

I would think the I grade wheel would cut even faster than the K grade wheel. I am on my second 60 grit I grade 3x wheel and it cuts vary fast, but wares even faster. I just ordered a 3X 80 K wheel from Hartville. They have had them all on sale for over a month. They must be popular, most are on a two week back order.

[Mike Spanbauer]

Paul, I pulled the wheel *off* the grinder and placed it on a known flat surface (my granite surface plate I believe it was) and in doing so, seated the wheel flush w/ the wheel. One thing to consider doing (although I did not need it) is if the arbor ring (or grinding wheel race / insert) is too shallow - you should use a couple of flat washers in order to center it. Hope that helps.

OP: The Norton K's are what I will be replacing my woodcraft grinders stones with once they wear or get annoying. They cut okay, but the norton's cut very, very nicely and are what I was used to when in my fathers shop so many years ago.

mike