Why doesn't Tormek replace stone with a CBN wheel?

[Ken S]

Rich,

Both CBN and diamond wheels gravitate toward their optimal use. CBN, with its high speed heat tolerance, is used by turners with their high speed dry grinders and hss turning tools. If you watch Dave Schweitzer's videos, he prefers the 3450rpm eight inch grinders. With CBN and hss, heat is not really a problem.

The Tormek must work in several environments, from turning tools and planer blades to delicate carving tools. With its water cooled slow speed motor, it can handle the much harder diamond grinding wheels.

I started using CBN wheels with my Tormek before diamond wheels became available. If I was starting out today, after the SG-250, I would add one of the Tormek diamond wheels. In my case, I would start with the DC 360 grit coarse wheel. I have found it cuts more quickly than the 220 grit SG or SB wheel.
Eventual third and fourth wheels would be the other two diamond wheels. You pick the order depending on your needs. Frankly, I would not choose CBN or the SB today. I believe the Tormek diamond wheels have eclipsed them. Your thoughts may certainly differ; this is just my opinion.

I reshaped a new 3/4" spindle roughing gouge today. The bevel was steeper than I wanted. I reground it to 35°. That would have doable with the SG, but very time consuming. The DC did the job in a reasonable time. It was no speedster, however, it kept grinding. I could hear the grinding and watch the progress.

The SG can work with higher grinding pressure. The diamond wheels should always be used at low grinding pressure.

I think Tormek chose quite logically with diamond wheels.

For the record, I believe the Standard "Original" SG which comes with the Tormek is the ideal grinding wheel for most of us. For sharpening woodworking tools and kitchen knives, it does trooper service at minimum cost. For sharpening several kitchen knives occasionally or the home shop chisels and plane blades, I would find it difficult to justify the extra three dundred dollars US each for the three diamond wheels, unless one is a Tormek junkie.

Marie notified me that Tormek just placed more detailed information about the diamond wheels on the website. It is worth reading.

Ken

[GKC]

I think Tormek chose quite logically with diamond wheels.
Ken

I quite agree.  Given that you don't have the melting-diamonds-at-high-heat problem, it would seem that harder diamonds are the way to go. 

It is worth noting that, if you do not need the flat sides of the Tormek diamond wheels, the 10"x2"x12mm CBN wheel that Woodturners Wonders sells in its "Spartan" line for the Tormek is $180, whereas the DC-250 is about $330. Also, the CBN wheel is available in 200 grit, which might be faster than the 360 grit of the DC-250 (it is difficult to say without trying them side by side).

Tormek recommends water with their diamond wheels but says that they can be used dry.  Woodturners Wonders says to use the CBN wheels dry, but it looks like they could probably be used wet (with a corrosion inhibitor).  If there are variations in the wet and dry cutting performance of the two abrasives, that too could be an interesting differentiator.

I have the CBN wheel and hope to get a DC-250 when Tormek gets the diamond wheels back onto the market, so I will be looking to see how they compare. 

(Ken, I think you have CBN and diamond wheels on hand, so perhaps you already have some views on whether you prefer one wet and the other dry, both wet, both dry etc.)

Gord

[RichColvin]

I like theses two charts from the new info that Marie mentions.

Kind regards,
Rich

[GKC]

Marie notified me that Tormek just placed more detailed information about the diamond wheels on the website. It is worth reading.
Ken

Like Rich, I found the new information on Tormek's site to be helpful--Ken, I think you have been asking for this for a while, perhaps you were heard.

I have made it into a pdf so that I could find it when off-line, attached.

Gord

[Ken S]

I like theses two charts from the new info that Marie mentions.

Kind regards,
Rich

Rich,
I like the tables, too. However, they don't tell the whole story. As noted, Diamond is the hardest substance by a wide margin. I have a DMT flattening plate specially designed for flattening sharpening stones. DMT has a reputation for quality, and I am sure my plate is no exception. It did a great job flattening my water stones and India oil stone. I made the mistake of trying to flatten my grandfather's two sided oilstone. I think the medium side is carborundum. The five dollar oilstone almost completely destroyed my two hundred dollar diamond flattening plate. The plate still works, however, most of its useful life is now gone.

Therefore, I would tread lightly with comparative hardness charts.

Ken

[GKC]

Ken's cautionary tale reminds me that an abrasive coating is only as effective as its bonding to the substrate.  CBN and diamond particles on a lapping plate or wheel will always be harder than steel (or sharpening stones) I target them at, but if I dislodge the particles, the target wins.  I would have expected the monocrystalline diamond particles on a DMT lapping plate to stay intact while flattening a silicon carbide stone, but evidently not. 

This makes me think about comments that CB and others have made about these "last forever" wheels: if you prong them with your tool, you might wish you had been working on a stone that you could restore.  Has anyone dinged one of their diamond stones yet?

Gord

[Ken S]

Gord,

You are correct; I have been asking this question for a very long time. In fact, my question predates the diamond wheels by several years.

I keep a print copy of the handbook in my satchel. I often refer to it during quiet moments and have reread the entire handbook numerous times over the years. I have also loaded it onto my ipad.

Torgny Jansson did an outstanding job with the handbook. The SG grinding wheel is very well covered. Unfortunately, since his passing, almost nothing has been done to update the handbook. The SB and SJ wheels share only two paragraphs. The SB I purchased in 2010 has essentially remained in the box on my shelf. Whenever I have tried to use it, it quickly glazes and does not cut. The only reason I have kept it is because I know several experienced users who like it. I have found several alternative stones, the Norton 3X; CBN; and most recently the Tormek diamond stones. I freely admit that my problem with the SB is probably user ignorance rather than a defective product. Until Tormek decides to provide in depth information on the SB, it will continue to collect dust on my shelf.

I really like the new diamond stones, both the two 200mm and the three 250mm. Information has been lean, however, by using the ACC and a very light grinding touch, I have had very satisfying results. I welcome the new information referenced by Marie. The new Tormek diamond wheels are innovative; they deserve good support.

I would mention that Tormek has produced some outstanding videos. The pick of the litter is the turning DVD done years ago by Jeff Farris. I hope marketing will not "upgrade"it by only substituting a T8 and a new face. Jeff and the SuperGrind are as solid as ever, however, new grinding wheels and jigs have been introduced. Also, new questions have arisen, such as the 40-40 grind and the Alan Lacer skew. The turning DVD definitely needs a real revision.

Knife sharpening has also moved beyond the SuperGrind Jeff Farris stalwart you tubes.

I like the videos Alan Holtham has done, especially his outstanding DBS-22 video. We need more of them.

Yes, Gord, I have been asking this question for a long time. Actually, we seem to finally see some movement. I remain positive and hopeful.

Ken

ps I just read your last post. I have no expectations of any abrasive material lasting "forever". I do believe the Tormek diamond wheels to outlast the Original wheels long enough to be cost efficient. In my case, with a home shop and being 68 years old, I expect they will outlast me. I am happy with that, and consider them fairly priced.

[Sigs]

Seems the only CBN wheels I have located are horribly expensive. Can buy 2 diamond wheels for the same price. We want the diamond wheels for certain HSS and ceramic knives.Why not just stick with What's available?

[GKC]

Sigs, I don't know where you have been looking, but there are certainly CBN wheels that are not twice the cost of the diamond wheels (try D-Way, Woodtuners Wonders).  But there are advantages to the Tormek diamond wheels, so they might be best for you.  There are supply chain issues, they are still out of stock in my part of the world.

Gord