CBN testing first report

[Ken S]

I have been working with three CBN grinding wheels. I will make a more extensive report available later. In the meantime, I thought many of the members might appreciate a short "reader friendly" report. My testing is ongoing, however, I feel confident in answering most of the basic questions at this point. The answers are based on my first hand, admittedly brief experiences.

Is it possible to use CBN wheels with the Tormek? YES

Can they be used wet and dry? YES TO BOTH. (see explanation)

Do they fit the Tormek without adaptation? YES

Do they wear out? Two of the CBN wheels I am testing are eight years old and still cutting very well. From a practical standpoint, it seems a non issue.

Do they stay flat and true? The two eight year old wheels are still flat and run true. CBN wheels are made of steel or aluminum and are accurately balanced at the factory. I have read of some wheels being defective. The dealers involved seem honest and conscientious about replacing them. I am not worried.

Do they overheat tools? NOT IN MY EXPERIENCE. Used wet, they are Tormek cool. Used dry, after long grinding (turning gouge major reshapeng) the gouge became warm. I could still hold it.

Is there a lot of grinding dust? NO. There is some when used dry. It is only steel from the tool. There is no abrasive dust. Used wet, there is no dust, and the small amount of metal removed is contained in the water trough. The trough stays cleaner with no abrasive dust from the wheel.

Some CBN wheels have a thickness of 1 1/2 inches (25mm). Is that a problem with the Tormek?
Not in my experience. In use, I did not notice the difference. The wheels fit the Tormek without spacers. They are "plug and play", especially when used with the EZYlock shaft.

Do the eight inch wheels work with the T4? YES,VERY WELL. Tormek does not offer the SB blackstone in 200mm diameter. The wheel I purchased is for my T4. It makes my T4 "turbo".

Do CBN wheels make regular Tormek wheels unnecessary? It depends. For reshaping turning tools, it is a definite yes. In fact, going directly from either the 80 or 180 grit wheels directly to the leather honing wheel, both wheels produced surprisingly sharp and polished edges.

With no personal experience, I believe CBN wheels are the answer for frustrated planer blade sharpeners. Unlike the SB blackstone, they do not glaze and the diameter remains constant.

CBN does a very adequate job with high carbon chisels. Direct from the wheel to the leather honing wheel the BESS sharpness readings approached the traditional three step SG sharpening. I prefer the feel while grinding and the smoother scratch pattern of the SG graded coarse. In a hurry, with a CBN wheel already on the Tormek, I would use it. Given my choice, I would use the SG.

Unlike the Tormek SG and SB wheels, CBN wheels are only one grit per wheel. I suspect those who venture down the CBN path will eventually purchase several different grits.

What about radius and flat area CBN wheels? Sorry, I have no experience with either of these. A turner might find the radius wheel useful. As to the CBN flat side, I leave that up to the reader. I probably have more than thirty chisels. For serious flattebing, I would use a flat piece of glass with abrasive.

For wet grinding, I found that rust was a problem with plain water. Using Honerite Gold diluted 1:25 has prevented rust so far. One of my sessions had the wheels in solution for eight hours. I then carefully dried, oiled and hung the wheels.. No sign of rust. These tests are ongoing.

All three of the wheels I am testing are flat steel wheels from D-Way. The 8 inch 180 grit is a new wheel I purchased from D-Way to use with my T4. The 10 inch wheels, one 80 grit and one 180 grit, were generously loaned to my by Dave Sweitzer of DWay for the tests. They are eight years old and still work very well. I requested two aluminum wheels from another vendor for the test. (The test way originally just to compare wet and dry operation on the Tormek.) The other dealer responded that CBN wheels are designed to work dry and did not seem interested in participating.

I wish to emphasize that my using D-Way wheels in no way implies any inferiority of other brands.

I will post more as testing progresses.

Ken

[grepper]

Thanks Ken.  Very informative.

How would you compare the cutting speed to regular abrasive wheels?

I wonder if Mr. Sweitzer would lend you a 600 grit wheel for testing.    I'm curious if it would be capable of removing enough metal to sharpen a really dull knife, and yet leave a smooth enough finish to be all that is generally required for basic kitchen knife sharpening.

I've found that somewhere around 600 grit with a good honing works well for a kitchen knife.

[WolfY]

Thanks Ken,

This is very interesting and informative.

If the wheel is 1 1/2" are you using spacers to compensate for the thickness to fit the shaft?

Have you thought of using the CBN wheels that are dedicated for the T-2? I know they are only 6".
Don't remember for sure the grits they have (300+600 I think) but remember they have 2 grits as standard.

Happy New Year to all.

[Ken S]

Grepper,

With the high carbon chisels, the 180 grit CBN and Tormek SG-200 seemed evenly matched for grinding time.

I found the CBN wheels much faster than the SB blackstone. I have always had trouble with my SB glazing. This may be me, so I hope other SB users will post. The CBN wheel cuts consistently from start to finish.

D-Way only stocks 80 and 180 grit wheels. Other grits are special order; I doubt Dave has any setting around. Hopefully Wootz will post again when his replacement wheel arrives and settles down to a true 600 grit. My gut feeling is that a 600 grit CBN wheel might be useful for a busy farmer's market sharpener, and perhaps overkill costwise for the home sharpener.

Dave has been very generous. I hesitate to ask for more.

WolfY,

The 1 1/2" wheels come with a steel reducing bushing. The bushing has a shoulder on one end. Between the Tormek washer and the bushing, the wheel threads nicely on the Tormek shaft. Remember, Tormek grinding wheels, although 50mm thick, they are also inset. My new D-Way wheel also came with a washer. The two used wheels did not. I suspect that was a very minor oversight, which did not effect their use.

I believe the T2 wheels are actually diamond. The basic T2 looks like a jazzed up T4, so I assume they are 200mm in diameter. I know nothing about them.

Ken

[SharpenADullWitt]

Where I have seen the wheels talked about more, are in forums dealing with Turners.  (they seem to be more the buy/cry once and use it mostly for that)
I expect they keep their other wheel(s), for the rarer "flat woodworking tools" as I have heard them called.

What I would be interested in, is your opinion of them and rough shaping, verses your Norton 3x wheels, on both your style machines (bench and Tormek grinders).  Since they don't wear as the SG/SB stones, I expect that is where the CBN turner/users, gain real advantage.
For me, all my other grinders are higher speed (3450).  For the cost of a slow speed bench grinder, and the Norton (or other) wheels, it might be a wash, once you figure out payback verses use.

On a side note, not worth a pm, I am still awaiting an email about that other thing.  I expect they may be closed due to holiday's and if I don't hear something by next week, I will contact them again.

[Ken S]

SADW,

Your experience matches mine. Most of the people I have read about with CBN are turners. I also recall hearing that most of the US Tormer buyers are turners. With the impressive lineup of Tormek jigs and accessories for woodturning tools, this does not surprise me.A turner may cut through more wood with a gouge in a day than a flat woodworking chisel sees in a lifetime.

Looking at the dwaytools videos, it is apparent that Dave Sweitzer is a very active bowl turner.

Comparing the CBN wheels and the Norton 3X wheels for reshaping: The CBN wheels are much more advanced. I found the 3X wheels a significant improvement over the traditional gray wheels. The CBN wheels are a significant improvement over the 3X. CBN wheels absorb most of the heat. 3X wheels cut well, but they also transfer most of the friction heat to the tool. 3X wheels give off abrasive grinding wheel dust detremental to the lungs and need periodic dressing and retruing. They are narrower then other wheels for Tormek, only one inch.

On the positive side, 3x wheels grind significantly faster than the SG or SB. I have not experienced glazing with them. Using them wet with the Tormek requires making up a 12mm bore adaptor, however, when this is done, they are cool, dustless and sparkless, like a traditional Tormek wheel.

For someone who reshapes only a few tools, a 3X wheel is cost effective. For around fifty dollars US, a Tormek user can have a reshaping wheel which outperforms the SB.

The 3X has one distinct advantage over CBN wheels: It cuts mild steel without clogging. I used the 46 grit 3X wheel on my 3450rpm six inch dry grinder to grind off major mushrooming from two slitting wedges.

Having used both, I believe a Tormek turner would be better off, even on a tight budget, to get a CBN wheel.

Regarding the cost of a slow grinder, an eight inch slow Baldor grinder, like a Delta Unisaw and a Conover lathe, was one of those tools which never went from my wish list to my purchased list. At my age and life responsibilities, my list major tool purchase was my T7 in 2009. Comparing like for like, the Baldor is the Tormek of dry grinders. Using either 3X or CBN wheels has allowed me to get as close to the Baldor as I realistically need to be without the investment in space and money required for a Baldor.

I am surprised that CBN wheels are not more popular with sharpening planer blades.

Ken

[Ken S]

Just a couple side notes from my CBN chisel tests:

1) The constant diameter does away with having to compensate for wheel wear with the kenjig and similar tools. With a CBN wheel, Dutchman's booklet of tables could be reduced to just the 250mm table. This is not exactly ten inches, but is "within tolerance".

2) Quick work is even quicker. Today I wanted to regrind one of my sharpening chisels on the eight inch diameter T4 wheel to check the bevel angle. For precision chisel sharpening, I prefer to set up with the SG wheel. For a test measurement, I just used the 180 grit CBN wheel dry. It was very quick.

Incidentally, the eight and ten inch wheel bevels looked the same to my eye using an angle gage. To my surprise, the amount of hollow grind looked "the same" as well. My mind tells me there is a difference, but my eye did not see it.  Much can be learned from using the sharpening chisels.

Ken