Diamond vs CBN for Torrmek style grinder

[Alex Zeller]

I'm posting this hear as I think turners have a unique view on sharpening tools (because of how often we need to do it). I got my Grizzly clone of the tormek for sharpening things like axes and scissors. The standard wheel that came with it was up to the task just fine and do to the light use really hasn't worn much. But now that I've joined the turning world that's changed. I don't need to do anything in a hurry but I wouldn't mind not wearing down the stone wheel I got now to the point where it's useless (The need could arise where swapping back to it for a specific item could come up). So I don't see a lot of point waiting too long before upgrading.

I thought Tormek would of had their diamond wheels out now and there would be plenty of reviews but that doesn't seam to be the case. The speakers on my laptop suck so I can watch videos but can't hear them so haven't watched a lot of them to see if there's a good comparison. I have learned some, like diamond will not work on high speed grinders and CBN on soft metal but was hoping others could chime in.

My use will mainly be turning tools. I'm not opposed to getting another grinder if it's the best solution but noise and dust are an issue since I usually turn at night in the basement after the wife has gone to bed. I also have several tormek jigs (like the one for doing gouges) so I'm kind of invested in using what I have. However I see tormek does have an adapter to use their jigs on a standard grinder.

So what are people's opinions of a diamond wheel over a CBN? A good quality one of either is going to cost around $300. Can I get away with just one grit and use my regular 6" grinder for reshaping tools or should I just plan on getting at least a course and a fine grit? I don't want to switch wheels but that's based on a stone wheel. With either the CBN and diamond they should just be swap and go without the need to true the stone up so I'm guess that I'm thinking I have a flawed old school line of thought with newer technology. Will both last a very long time or will one have a longer life than the other? I'm asking in part because I think there's plenty of people who are going to be asking questions like this and hopefully others besides me can get answers.

[Bill Boehme]

I bought a 1000 grit aluminum CBN wheel from Woodturners Wonders a year ago. Initially, the coating of CBN crystals was very thick so for a while a lot of the CBN crystals were flaking off and the tool edges were not what I expected from my Tormek. On the plus side it cut so fast that it could be used for shaping despite being 1000 grit. The biggest negative is that Woodturners Wonders say not to run the wheel in water which defeats the whole purpose of using a Tormek -- no metal dust. After several months the excess CBN was gone from the wheel and the tool edges were almost as good as I was accustomed to getting with the standard Tormek graystone when graded to give a smooth edge. However, there are now bare spots on the wheel although it still works, but it reminds me of some of my cheap card files that are well on the path to being worn out. After all this I wouldn't recommend the CBN wheels for the Tormek. I think that they are great for dry grinders, but I would prefer steel rather than aluminum on a dry grinder.

The US dealers for Tormek are now accepting pre-orders for the diamond wheels. There are three different grits. They are designed to run in water, but they also require their special anti-corrosion additive (it's not the same as antifreeze). They are supposed to be available for shipment in a couple weeks or so. The only turner that I know of who has been using them for a while is Glenn Lucas. The main disadvantage is that unlike the stone it can't be graded, but that is also an advantage. They say that you can also use the diamond wheel to sharpen carbide cutters.

[Bill Blasic]

I myself would keep the stone and invest in a grinder big enough to handle the 1 1/2" CBN wheels (so much nicer than the 1" wheels). I use 80 and 180 CBN.

[Reed Gray]

Well, a few things about wheels. Glenn did say a couple of things about the diamond wheels. One was that after a year of cutting, they still cut like new. Two was that diamonds are twice as hard ad CBN. I don't think that is correct. I did talk to the Tradesman/Toycen grinder guy at the Symposium about that since he does make diamond wheels and he said diamond is only about 20% harder than CBN. That, I think is closer to correct. So, no even attempting carbide on CBN wheels. Diamond can handle hardened steels as long as the speed is kept very slow. The DC motor on the Tradesman grinders can be lowered to the point where heat build up is not a problem. On the standard 1700 slow speed grinders, that speed is too fast, it generates enough heat to damage the diamonds, so no to that one.

Now, about CBN wheel wear. I talked with Dave Schweitzer of D Way about my old wheels that I retired after a number of wheels. He commented that the amount of wear on CBN wheels is really minimal because of hardness. The thing that is mostly responsible for them cutting more slowly is 'gunk'. I turn a lot of very wet madrone, which is very sticky, and my wheels were kind of black from it. Dave said to take the wheels and soak them in water and dish soap (I used Simple Green) for several hours and then take a scrub brush to them. This really took off almost all of the black. There is a worn spot mostly in the center of the wheel. I did try to touch up a couple of carbide bits I had brazed onto some old McNaughton blades. This probably ruined the wheels and dulled them beyond repair. I do have another set on the grinder that are fairly dark, and need to do the soak and scrub on them. This build up is one reason why I like a bit of lapping fluid on my tool bevels (put it on the wheel and you get a spray of it on you if you are in the line of fire...). It does a lot to clean up the gunk. Maybe some day, I will set up one set of wheels for just dry wood and see how that works. Glenn did say that he would find 'good homes' for his CBN wheels after a year. He turns a lot of wet wood as well, so no idea. I may have to ask him..

If I wanted a CBN wheel for serious reshaping of tools, a 60 grit on a 10 inch high speed grinder would do the trick. I use a 36 grit belt on a 1 1/2 hp belt sander for that. 80 grit does minor reshaping, but not serious reshaping unless you don't care about time. Do use lapping fluid. For general cutting, the 180 grit will do for about 90% of your cutting. Tom Wirsing's article in the AAW Magazine not long ago said that he prefers a 600 grit edge for general use. Both he and Glenn think that the 600 grit edge lasts as long or longer for general use for turning. Haven't had the chance to chat with Tom about it, but his opinion is that the 600 grit edge provides more teeth so they dull at a slower rate than a coarser edge. In my experience, the 600 grit edge is great fir fine finish cuts, but not good for heavy roughing. When I told Glenn about this, he said some thing about that puzzling him. I hope to get some play time with him at the upcoming Oregon Woodturning Symposium here in March where he will be one of the demonstrators. Maybe I can show him how to use scrapers....

No clue about the delaminating of the WTW wheel. This is the first case of this I have heard of. Anyone else? In the ongoing discussions with Dave Schweitzer, he says there are two methods of bonding the CBN to the wheels. One is electroplating which is the superior method which will take more use and abuse. The other is resin bonding which works, but is more prone to flaking off, especially due to heating. I have no idea if that is how Ken Rizza has his wheels done. I have no idea how water or other fluids on the wheel will effect the bonding. With the electroplating, no problems. With the resin bond, maybe. Dry grinding would not be a problem if there is adequate duct collection. Some of these exotic metals have very hazardous stuff in them that we do not want to inhale. This is a health and safety issue that we need to address. Safe and affordable DC for grinders....

I would expect the diamond wheels from Tormek to be very high quality. I forgot to ask the Tradesman guy if he was going to start marketing diamond wheels to the woodturners.

robo hippy

[Tom M King]

CBN if dry.

Diamond if wet.

[Kyle Iwamoto]

I got a 600 grit CBN for my Tormek a few years ago when they first came on the market. I disliked running it dry so I use import car (aluminumn) radiator coolant. So far, so good. I don't leave the wheel in the coolant when I'm done. Im no expert but I would have a hard time imagining water affecting electroplating or resin bonding.

[Chris Parks]

I can't see why using a CBN with water would cause any problems, in fact if someone told me that he had better have his facts straight because I would challenge it. The wheel is aluminium with non porous cutting surface, about the only thing that could happen is the operator needs to wear a raincoat.

[Bill Boehme]

I can't see why using a CBN with water would cause any problems, in fact if someone told me that he had better have his facts straight because I would challenge it. The wheel is aluminium with non porous cutting surface, about the only thing that could happen is the operator needs to wear a raincoat.

It could be the plating metal assuming that it is a metal. Galvanic corrosion from dissimilar metals in an aqueous solution (water) is a significant issue especially the further apart the metals are on the galvanic scale. Using the right plating metals can go a long way towards mitigating the problem. There are anti-corrosion additives that can be used with water. I think that the biggest problem would be if the wheel were left in water and not removed when through using it.

Reed,
Hardness doesn't necessarily correlate to wear resistance, toughness, etc. I think that Glenn Lucas and The Tradesman rrep may both be correct, but were saying different things. It is possible that two materials could have nearly equal hardness while one of them has many times the wear resistance of the other.

I didn't mean to imply delamination. What I meant was that I have worn through the CBN and down to bare aluminum in a few spots. Since the aluminum is a lot softer than HSS, the wheel develops a pothole in the worn through spots. My conclusion is that wide flat beveled things like skews, hand chisels, plane irons, jointer and planer blades, scissors and knives would all work well with the CBN wheel on a Tormek. However, gouges and many other turning tools would best be done with the Tormek standard gray wheel or the Tormek Blackstone. I am hopeful that the diamond wheels work out because I have visions of touching up a bunch of dull carbide cutters that I have saved.

[Reed Gray]

Hey Tom, could you explain this???


CBN if dry.

Diamond if wet.

Bill, you have me wondering about the delamination. So, does that mean that because the aluminum is softer, when you sharpen the harder turning tool metals, it kind of dents the under metal under the CBN cover? I would guess this would mean that the bonding method isn't very flexible without cracking and breaking...

robo hippy

[Bill Boehme]

.... Bill, you have me wondering about the delamination. So, does that mean that because the aluminum is softer, when you sharpen the harder turning tool metals, it kind of dents the under metal under the CBN cover? I would guess this would mean that the bonding method isn't very flexible without cracking and breaking...

robo hippy

One thing that concerned me about an aluminum wheel for the Tormek from the beginning is that unlike the dry grinders where tool force against the wheel is only a couple ounces, the force against the wheel on a Tormek is far greater. For tools like gouges that have a very small contact area this translates to a very high pressure. I should mention that the aluminum wheel isn't some little dainty thing it's T6 tempered and weighs in at about 9 pounds 9 ounces and probably rivals the weight of some 8 inch steel CBN wheels. Even so, steel is much harder and the substrate hardness probably matters.

I would be interested in hearing how well the nylon CBN wheels from Woodturners Wonders are holding up. They have been on the market for nearly a year.

[John K Jordan]

One thing that concerned me about an aluminum wheel for the Tormek from the beginning is that unlike the dry grinders where tool force against the wheel is only a couple ounces, the force against the wheel on a Tormek is far greater.

I use 8" aluminum CBN wheels on bench grinders (80, 220, and 600) and 10" aluminum CBN wheels on a Tormek (1200 and 600). All work well dry but I do sometimes dribble a little diamond lapping fluid on the Tormek. https://www.amazon.com/gp/product/B004NPIMU8

I don't understand the concern about high force against a Tormek wheel. When I sharpen my spindle gouges on the Tormek the force is extremely light. I haven't measured and calculated the force per unit area but I'm not worried. I use a much higher force when reshaping heavy tools on coarse CBN wheels on the bench grinders but that doesn't concern me either.

If available and the price was good I'd get diamond instead for the Tormek. From the technical literature I found no advantage of CBN over diamond for grinding where the speed is low enough to not damage the diamond from the carbon issue. The diamond is harder and will last longer. It will also easily sharpen carbide and ceramic, both of which I do with diamond plates and other diamond wheels.

JKJ

[Alex Zeller]

Interesting viewpoints and thanks to all for sharing. I knew that trying to pick just one to start with was going to be hard. Compromises always are.

From what I've been reading diamonds are anywhere from about 30% to 100% harder than CBN. But it's not just hardness that matters. CBN uses micro fracturing to constantly have sharp edges. I think grinding with a diamond surface just counts on the hardness of the diamonds to stay sharp. Once damaged I don't think diamonds can recover. I'll probably get the diamond wheel, still leaning towards 600 grit, when they come out. Down the road I think the best solution would be to get a low speed grinder and have two different grit CBN wheels that complement the diamond wheel. Like most things with turning sharpening seams like a place that just requires money to be spent for the best results.

[Reed Gray]

One thing that concerned me about an aluminum wheel for the Tormek from the beginning is that unlike the dry grinders where tool force against the wheel is only a couple ounces, the force against the wheel on a Tormek is far greater. For tools like gouges that have a very small contact area this translates to a very high pressure. I should mention that the aluminum wheel isn't some little dainty thing it's T6 tempered and weighs in at about 9 pounds 9 ounces and probably rivals the weight of some 8 inch steel CBN wheels. Even so, steel is much harder and the substrate hardness probably matters.

I would be interested in hearing how well the nylon CBN wheels from Woodturners Wonders are holding up. They have been on the market for nearly a year.

Bill, this has me stumped... Why do you use more pressure on the Tormek than you do on CBN wheels?

robo hippy

[Bill Boehme]

... I don't understand the concern about high force against a Tormek wheel. When I sharpen my spindle gouges on the Tormek the force is extremely light. I haven't measured and calculated the force per unit area but I'm not worried. I use a much higher force when reshaping heavy tools on coarse CBN wheels on the bench grinders but that doesn't concern me either....

Have you ever shaped a tool on the Tormek? Never mind that it's smarter to do that on a dry grinder. Also sharpening a skew and other large bevel contact area edges take forever. I will add that the 1000 grit CBN sharpened skews amazingly fast although the edge wasn't the same quality as I can get with a Tormek stone.

[Chris Parks]

Using a Tormek is akin to watching paint dry over several days IMHO.

[Reed Gray]

Nope, only use it for the honing wheel.... if I have to do serious shaping, that is what my 1 1/2 hp belt sander with 36 grit on it is for....

robo hippy

[Bill Boehme]

Using a Tormek is akin to watching paint dry over several days IMHO.

It sounds like you haven't ever used a Tormek. I can sharpen a bowl gouge on my Tormek just as fast as I can on my dry grinder.

Here is a short video that shows in real time how long it takes Glenn Lucas to sharpen his bowl gouge: https://www.youtube.com/watch?v=KeLx4gSvykg

and here is another: https://www.youtube.com/watch?v=rM7-s6wsQCA

[Kyle Iwamoto]

It sounds like you haven't ever used a Tormek. I can sharpen a bowl gouge on my Tormek just as fast as I can on my dry grinder.


I've given up on defending my Tormek. SO many haters out there that think it's slower than molasses on a cold day.......
Personally I think (I agree with you 110%) ONCE YOUR GRIND IS SET, it takes just a few seconds. My bowl gouge jig, I never change. Well, after taking in Stuart Battys advice, I may have to buy another jig for the 40/40 grind.......
Use what you like, but watching paint dry is not a true statement for speed. Not saying I can reshape a tool in less than 2 hours, but sharpening, it is very quick and you get the exact same grind every single time........

[Reed Gray]

They don't include the time it takes to put the gouge in the jig.... So add another 10 to 20 seconds. Not as fast as platform sharpening...

robo hippy

[Alex Zeller]

I only use mine to touch up the edge on my tools. As long as I don't forget to fill the tray with water it takes me less than a minute to adjust the tool rest to the correct distance from the wheel, put the gouge correctly in the jig, and put a new edge on it. That includes both sharpening on the stone and to hone it afterwards. I've actually made blocks of wood to set the tool rest distance and setting the gouge depth. The only tools that take time are the curved scrapers. But that's more a case of setting up the platform jig at the correct angle. I'm hoping that with a diamond wheel (or CBN) that doesn't change diameter I can make a jig for each tool to speed up setting the rest.

[Bill Boehme]

I've given up on defending my Tormek. SO many haters out there that think it's slower than molasses on a cold day.......
Personally I think (I agree with you 110%) ONCE YOUR GRIND IS SET, it takes just a few seconds. My bowl gouge jig, I never change. Well, after taking in Stuart Battys advice, I may have to buy another jig for the 40/40 grind.......
Use what you like, but watching paint dry is not a true statement for speed. Not saying I can reshape a tool in less than 2 hours, but sharpening, it is very quick and you get the exact same grind every single time........

I don't worry about defending what I use, I just use my Tormek and let others use what they want. I will, however, say what I like about using my Tormek. I also have a dry grinder that is more idle than the Maytag repairman. It's mainly if I need to reshape a tool that I use the dry grinder. My main problem with the dry grinder is the cloud of dust that it produces. It leads to coughing spasms, headaches, and grit all over everything.

It's not the cheapest solution, but I have three bowl gouge jigs each permanently set to the three different grinds that I use. I justified buying the second one several years ago because the first one was so old and there was a slight design improvement and then more recently I got the third one after a major design improvement.

[John K Jordan]

Have you ever shaped a tool on the Tormek? Never mind that it's smarter to do that on a dry grinder. Also sharpening a skew and other large bevel contact area edges take forever. I will add that the 1000 grit CBN sharpened skews amazingly fast although the edge wasn't the same quality as I can get with a Tormek stone.

Anyone who tries shaping on the Tormek more than once is a glutton for punishment or not thinking clearly. Pressing harder is not a solution for me.

The second thing I did when I bought and experimented with my Tormek was rig up a grinder to use the Tormek support and jigs. For a new grind I start with 80 grit CBN (if necessaray), refine with this Tormek jig using 600 grit, and then move to 1200 CBN on the Tormek. The 600 grit CBN is surprisingly fast and the convex curvature from the 8" wheel is not enough different from that of the 10" wheel to cause

390711

The Tormek water stone gives a better surface than the 1200 grit CBN as well.

I sharpen skews without a jig on the 600 grit CBN then hone on the Tormek leather wheel.

JKJ

[Bill Boehme]

Bill, this has me stumped... Why do you use more pressure on the Tormek than you do on CBN wheels?

robo hippy

I didn't mean to imply that there is a difference if both wheels are on the Tormek. What I was intending to say is there is a difference in pressure between a Tormek running at 90 RPM and a bench grinder running at 1750 RPM regardless of the type of grinding wheel. If I am sharpening a bowl gouge on a dry grinder I am using feather light pressure against the wheel. As just a very rough guess I would say maybe 10 times as much pressure when using the Tormek which still is not much pressure.

Sharpening a skew on the Tormek is a different story. Because of the very large bevel contact area it takes a lot more force to create the same pressure as a bowl gouge contacting the wheel. So, I really bear down on the bevel of a skew and it still takes several minutes to sharpen the skew on the Tormek standard aluminum oxide wheel. But, actually for a skew and other tools with a large flat bevel there is a significant time difference between sharpening with the standard stone on the Tormek and sharpening with a 1000 grit CBN wheel on the Tormek ... even if I used the stone grader to rough up the standard stone. After mulling it over a bit I think that I know the reason. When sharpening with the aluminum oxide gray stone, the large friable crystals on the surface gradually crumble into smaller sharp crystals which makes the wheel grit increasingly fine until eventually it isn't doing anything other than polishing the bevel. It's then necessary to use the stone grader to roughen the surface (With a standard bench grinder the speed is 20 times faster so the surface aluminum oxide crystals are being spun off rather than sticking to the wheel). When using the CBN wheel on the Tormek, the crystals don't crumble into smaller particles so the grit of the wheel doesn't change. Even though the Tormek CBN wheel is a 1000 grit, it was able to sharpen a skew very quickly. The only downside is that the edge isn't quite as smooth as the edge produced by using the aluminum oxide stone.

[Bill Boehme]

Anyone who tries shaping on the Tormek more than once is a glutton for punishment or not thinking clearly...

Guilty on both counts. :D


... The second thing I did when I bought and experimented with my Tormek was rig up a grinder to use the Tormek support and jigs. For a new grind I start with 80 grit CBN (if necessaray), refine with this Tormek jig using 600 grit, and then move to 1200 CBN on the Tormek. The 600 grit CBN is surprisingly fast and the convex curvature from the 8" wheel is not enough different from that of the 10" wheel to cause

I have a spare base from when I upgraded my Tormek 2000 to the T-7 configuration. I've been planning on doing that as soon as I got a round tuit. So far, it's just been square tuits.


... The Tormek water stone gives a better surface than the 1200 grit CBN as well.

I have no doubt about it. My 1000 grit CBN wheel is a long way from being satisfactory. Ken Rizza insisted that I would be completely happy with the 600 grit wheel. He allowed me to try out a demo 600 wheel at SWAT. I knew for certain that wasn't what I wanted and also I'm pretty sure that he isn't a real Tormek groupie.


... I sharpen skews without a jig on the 600 grit CBN then hone on the Tormek leather wheel.

From my very limited experience I believe that the higher speed results in a smoother surface for the same CBN grit

[John K Jordan]

From my very limited experience I believe that the higher speed results in a smoother surface for the same CBN grit

That makes sense to me, as long as the tool is kept in motion and the pressure is light (and the wheel is not brand new.). As with sanding, if the grit is not constantly moving across the surface individual grit particles can cut deeper grooves. The surface will get better as the new CBN wheel gets "broken in", which might take a month of use according to Reed's old writeup. A new wheel is FAR more agressive until the tops of the particles are knocked off.

If the 600 wheel you tried was relatively new it probably wasn't a fair test. When new, my 600 grit wheel worked more like a 180 but gives a much better surface now. If you ever get up this way you could try it.

JKJ