2 Stones, 1 Tormek?

[Pastor_Zatx]

Well to ask more accurately, can I run a CBN wheel on both sides of the T-8 or T-4 instead of the leather honing wheel on one side?

Thank you for answering my newbie questions.

[GKC]

I cannot see how this could be done, the honing wheels have a function in the drivetrains of the machines, so they are one-grinding-wheel machines.

Gord

[Pastor_Zatx]

I cannot see how this could be done, the honing wheels have a function in the drivetrains of the machines, so they are one-grinding-wheel machines.

Gord

Thank you GKC!

[RichColvin]

Jason,

You might want to look into the use of CBN wheels on Tormeks.  I am not a grinding expert, but remember reading that CBN was designed for the machining industry where high pressures and temperatures were required.  Diamonds won't fit this bill, so CBN is a better alternative.

I would bet that CBN doesn't work well at lower speeds.

Kind regards,
Rich

[Pastor_Zatx]

Jason,

You might want to look into the use of CBN wheels on Tormeks.  I am not a grinding expert, but remember reading that CBN was designed for the machining industry where high pressures and temperatures were required.  Diamonds won't fit this bill, so CBN is a better alternative.

I would bet that CBN doesn't work well at lower speeds.

Kind regards,
Rich

Thank you for your response, Rich. You and the other members here are a tremendous resource to the community.

I got the idea for using CBN wheels after watching wootz/knifegrinders videos where he uses the CBN wheels and the Tormek for his commercial sharpening operation and produces amazingly sharp knives with them. And, also, from personally using CBN rods on a Spyderco Sharpmaker, which is the slowest of all speeds as it's hand operated.

As others have mentioned, I think the idea that CBN gets gummed up from high carbon steels comes from untempered or incorrectly tempered metal which isn't the kind of steel I own in my high-end folding knives. But, if there's anything I've learned over my blessed long life, it's that I always have more to learn.

[Ken S]

Pastor,

I think we have to be careful of outdated information. I am one of the early users of CBN wheels on the forum. I believe Wootz was the first user.Back then, we did not have diamond wheels for comparison. I use my D-Way CBN wheels wet or dry, almost exclusively wet with anti oxident. While I have no complaints with CBN, I have not used them since I got the new Tormek diamond wheels. I have sharpened numerous Irwin Blue Chip high carbon chisels with each and have not noticed any  problems.

As a Tormek user, I have no use for high pressure and temperature grinding. You should definitely use very light pressure with diamond wheels. I don't remember for CBN, however, I feel lighter pressure would work better.

If I was beginning with the Tormek, after the SG which comes with the Tormek, my next wheel would be the 360 grit diamond wheel. For heavier grinding, it makes the operation go more quickly. The SG can handle finer grinding until one feels the need for a finer diamond wheel. I would skip CBN. I do not mean to disagree with Wootz; I just think he has not had the chance yet to evaluate the diamond wheels.

Ken

[GKC]

If I was beginning with the Tormek, after the SG which comes with the Tormek, my next wheel would be the 360 grit diamond wheel.  I would skip CBN.
Ken

It would be good to have a comparison of CBN and diamond wheels on the Tormek.  My $180 CBN wheels (10") seem to work very nicely wet and dry on my T8.  I have been waiting for diamond wheels to come back into supply, but now I am not so sure that I will be keen to plunk down ~$330 each for the Tormek diamond wheels. (I don't need the flat sides.)  All of which is to say, with cost as a factor, the performance comparison would be useful.

Gord

[Pastor_Zatx]

If I was beginning with the Tormek, after the SG which comes with the Tormek, my next wheel would be the 360 grit diamond wheel.  I would skip CBN.
Ken

It would be good to have a comparison of CBN and diamond wheels on the Tormek.  My $180 CBN wheels (10") seem to work very nicely wet and dry on my T8.  I have been waiting for diamond wheels to come back into supply, but now I am not so sure that I will be keen to plunk down ~$330 each for the Tormek diamond wheels. (I don't need the flat sides.)  All of which is to say, with cost as a factor, the performance comparison would be useful.

Gord

I would be surprised if there is much difference at all between the two, and I'd be even more surprised if what small difference there might be could justify the diamond wheels costing twice as much. I've used CBN and diamond in hand sharpening super steels for years and could not notice any significant advantage of one over the other in low-speed applications. Where there are vast performance differences is when you're talking high-speed and high-heat applications.

[Ken S]

So far, I have not seen what I would consider ideal wheels in either CBN or diamond. My ideal wheels would: 1) Be fully usable wet, without voiding the warranty. 2) Have abrasive only on the circumference to keep the cost down. 3) Be available in both 200mm and 250mm diameters. 4) Be available in a variety of grits. AND 5) to a lesser extent, Have a well designed 12mm bore. If a reducing bushing is used, it should be stainless steel.

Until I see such wheels available, I am leaving the jury out. Feel free to disagree with me. In the meantime, I will continue using both.

Unfortunately, we do not yet have fully information on either product. From the Tormek Handbook, we have the following specifications about the SG:


"The Stone is Not Running True
The stone should run true radially (up and down) within ±0.2 mm (total 0.4 mm or 0.016"). The axial (sideways) tolerance (which has no influence on the grinding result) is max ±0.5 mm (total 1.0 mm or 0.04")."

I have not seen any similar specifications, either from Tormek or any of the CBN vendors. There may not be a problem; I would just feel more confident with published specifications. If an SG wheel gets out of tolerance, it can be trued with the TT-50. CBN and diamond cannot be trued.

I have not yet seen enough information or worked with it enough to decide if the side abrasive is worth the extra cost. I would like to see Tormek sell diamond wheels in both diameters both with and without the side grit.

Ken

[Ken S]

I was poking around the Packard Woodworking site and found this in the description of their CBN wheels:

"CBN Wheels are used for grinding hardened high speed steels and should not be used on carbide or softer tool steels."

The Tormek SB wheel is listed as being suitable for carbide "touch up". The Tormek diamond wheels are listed as carbide compatable. I don't sharpen carbide, however, it I did, this could be a deciding factor, at least for one wheel.

Ken

[GKC]

CBN wheel aficionados will insist that their wheels can touch up carbide tools, and D-Way says their CBN wheels sharpen carbide, but I think that there is general agreement that diamond abrasives are the way to go for carbide. 

If I were making only one of my Tormek wheels a diamond one for this purpose, I would get the "extra fine" Tormek diamond wheel, to get a clean edge.

But with that said, if carbide sharpening capability were the reason I was getting a diamond wheel, I would want to hear some reports of people sharpening carbide tools at the low speeds of the Tormek before I made the purchase.  It might be rather slow and the edge might not be great.

Presumably Tormek has tested these parameters, I wonder what their results were.   

Gord

[RichColvin]

I have found that Design and Use of Cutting Tools is the best book on sharpening carbide tooling.  It was written in 1952 by Leo J. St. Clair.  He was working in the industry as it was changing from HSS to carbide tooling (lathes, milling, drilling, etc), so both are covered well. His experimental data helps validate or disprove many theories.

There is a bunch of stuff in St. Clair's book regarding tooling shape (which I have summarized on the Sharpening Handbook), but for this discussion, the key take-aways are :

    1. Sharpen in two steps :
        a. Get close to the final sharpening on a lower grit wheel, and then
        b. Finish on a higher grit wheel.  This is to minimize cracking in the grinding edge.

    2. Never use water to cool carbide when it gets hot.  It will crack.

I used St. Clair's techniques today when sharpening the tooling with carbide inserts that I used when working on my metal lathe.  I used my high speed grinder to sharpen the tooling (step 1a), and then finished up on the SB stone (step 1b).  I turned aluminium, cold-rolled steel, and hot-rolled steel.  And I can say that this process left a really smooth finish.


Now, all that said, there is a very good article titled "Modern Tool Steels and Grinders" by Tom Wirsing in the June 2018 edition of "American Woodturner" (the journal of the American Association of Woodturners).  Tom addresses the sharpening of tools which are made from particle metals / powder metals (M4 and A11/CPM 10V) vs. HSS (M2 and M42).  His article shows good microscopic views of the tooling using different grinding media :  both 60 grit friable grindstone and 600 grit CBN.

This is a good article as it addresses particle metals, including how and why that technology is used to make the tooling.  But it doesn't get into the depth of research that St. Clair did for more traditional carbides (formed by forming molten steel with various additives).  None-the-less, it is better than anything else I've seen.

And here is the key point :  I believe you should judge the advice by the output of the person advising.  Tom Wirsing is an AMAZING artist.  His work can be seen on the gallery on his web site ==> http://www.thomaswirsing.com.


As a final note, there are quite a few carbide tools that are based on being discarded after use rather than being resharpened.  The Hunter tool (http://huntertoolsystems.com) uses a pre-sharpened cutter which they advocate has a nano-grain structure.  This enables a very finely sharpened edge which is delivered already sharpened.  As it gets dull, the wood turner is to rotate the cutter until all 360° have been used.  Then the wood turner is to replace it with a new one ($15-25 each).  Quite frankly, I believe trying to sharpen this would cause more bleeding that it would be worth !

Kind regards,
Rich

[Ken S]

Well to ask more accurately, can I run a CBN wheel on both sides of the T-8 or T-4 instead of the leather honing wheel on one side?

Thank you for answering my newbie questions.

I cannot see how this could be done, the honing wheels have a function in the drivetrains of the machines, so they are one-grinding-wheel machines."

Getting back to the original question, correctly answered by Gord:

The original Tormek concept was for a large single, fine grit, natural grinding wheel running in a water trough. This was powered by an electric drill. the other end was the drive wheel, which reduced the rpm of the motor to a manageable speed for the water trough. The leather honing wheel and universal support bar came later.

During this time period, the 1970s, I was using my garden variety high speed six inch dry grinder. My dry grinder cut faster. Its six inch wheel left a distinct hollow grind, favored for "two point" sharpening. I, like so many sharpeners, frequently blued my edges, ruining the temper of the edge. In my opinion, even this early Tormek was a giant step ahead of conventional grinders for woodworkers.

Progress marches on. Tormek added the electric motor, the incredibly versatile universal support bar, and gradually switched to the present manmade aluminum oxide, Super Grind wheel, which could be graded between 220 and 1000 grit. With the added leather honing wheel, this one wheel machine offered the user grinding from 220 to 1000 grit, plus leather honing/polishing. The SG wheel served as the only Tormek wheel until 2010. Then the SB blackstone for harder steels and the 4000 grit SJ Japanese polishing wheel were introduced.

Soon sfter, some pioneering Tormek users began adapting CBN and Norton 3X wheels to the Tormek. There were some wear problems with the early CBN wheels. (Read Wootz' early posts and Derek of Perth's online comments.) I have not seen recent posts about these problems; the manufacturers seem to have resolved them.

In addition to CBN, we have the diamond option from Tormek. Neither option has been around long enough (in Tormek use) to have accumulated extensive (or adequate) usage data. Already, the present 250mm Tormek diamond wheels are the second generation distributed by Tormek. Generation one was introduced in 200mm with the T2. We have seen several configurations of CBN wheels.

I predict that in the next few years we will see new models of both diamond and CBN wheels. Eventually many of us will replace our present diamond and CBN wheels. They will not be worn out; they will be overshadowed by newer advances. In my opinion, Tormek is the only manufacturer which truly understands wet grinding. Third party manufacturers are still in the high speed dry grinding thought mode, primarily aiming for the woodturning market. I do not mean to imply that third party wheels will not work or work well with the Tormek, only that they are primarily designed for dry grinding. This may change someday and Tormek may have some serious competition in the grinding wheel market. It will be interesting.

Ken

Gord