C.B.N. coated for T7

[bobl]

Its Bob The Knife Grinder again,
I have seen on google a wheel that will fit the T7 and is advertised as so,  that is a Cubic Boron Nitride ( C.B.N. ) coated wheel.
I have experience of C.B.N.   The coating does not last long, although I use it on a Very fast machine. Does anyone know how long it will last on the T7 with it being a much slower grind.? Remembering that this is an electro plated  COATING of millimetres as opposed to a full wheel of grindstone as in the SG250 wheel.
Ken? anybody?
How long do  you think it will last, has anyone used a C.B.N. wheel on the T7.
Please don't say ( How long is a bit of string )
Because I will tell you the answer to that long asked question.
Which I will on my next forum post.
HaHa.
You are waiting now with baited breath!!!
I really do have the answer to that old adage of the string.

The first one to reply to this post with an informative answer to my C.B.N. T7 wheel, will get the solution to the conundrum of the string length.
Ken, You are good at trigonometry. Maybe you know the answer to the string question??? !!! 

[Ken S]

I was curious about the same thing. At this point, Tormek does not endorse CBN wheels. I have no personal experience with them, so can not really write about them. It does seem an interesting new technology. I believe grinding technology will change dramatically in the next decade or two. I have already seem changes. When I began sharpening as an adult in the early seventies, the most common choices were a six inch high speed dry grinder or oil stones. Water stones were just starting to become popular as were half speed grinders. Sharpening was a lot more work, and blued tools were common.

I believe that Tormek will continue evolving. I have seen substantial changed from tormek even since I bought my first unit in 2009. I look forward to seeing continuing developments in the scope of the Tormek.

Ken

[Rob]

I would echo that.  I think Tormek have got the balance between innovating to take advantage of newer ideas and technology and keeping their customers existing investments protected by remaining compatible just right.

[SharpenADullWitt]

There is an adjustable speed grinder that comes with that wheel, or a multitool belt grinder, that makes the Tormek look inexpensive.  Personally, I think I would like to try the CBN AND the SJ wheel in comparison,  I would think the SJ wheel would do pretty much the same for a better cost since it isn't just a coating.

[bobl]

ref. to sharpenadulwitts response,
For small wheels it costs around £174.
On a wheel as large as the T7 I would think it will be around £ 400 or more.
Unless you have more info it is a step I would not want to make without more info on cost.
Bob

[bobl]

Well, it looks like Ken was the first to reply.
So here is the answer to that long asked quetion of, " How long is a bit of string " 
The answer as promised is --- ----------  Twice as long as it is from the beginning to the MIDDLE.
Haha
Happy days.
Bob

[Stickan]

Hi,
Tormek has many different jigs for many different tools so we need a stone that can handle anything from small delicate woodcarving tool to tools with a larger surface with harder metal.
A CBN wheel or a Diamond wheel have one specific grit and our stones from 220 to 1000 grit plus the Japanese stone at 4000 grit.
We believe that our stones are the best solution for the wider range of tools and jigs.

Regards,
Stig

[Ken S]

Stig makes a very good point. One of the hallmarks of Tormek philosophy has been providing its users with as much versatility as practical at a reasonable cost. This idea goes way back. Even the SB and SJ grinding wheels are fairly recent additions. The traditional Tormek gave the owner the ability to sharpen many tools with just one stone (graded coarse and fine), a leather honing wheel with honing compound, and a few jigs. This has served many users very well for decades.

The traditional Tormek SG grinding wheel, although not specifically designed for high speed steel, does a credible job of resharpening HSS tools and a good job of sharpening them. Admittedly it is no speedster with major reshaping, however, the work is possible.

I believe the DBS-22 is a watershed product. It allows the user to sharpen drill bits going far and beyond a basic sharp drill point. It is amazingly versatile and quite well made. All this excellence comes at a price. It is expensive for the average homeowner user. By industrial standards it is not expensive. However, I believe it is priced beyond the reach of the typical home user.

Tormek AB, like any company, must consider price and demand points to remain in business. If twenty knife and square edge jigs are sold for every jig like the DBS-22, Tormek would not last long overspecializing. Several years ago, a forum member posted the desire to have Tormek sell an 8000 grit grinding wheel. I am sure this would be possible. However, looking at the price spread between 4000 and 8000 grit waterstones, and the cost of the SJ 4000 grit grinding wheel, I cannot see enough consumer demand to warrant the production cost.

Grinding technology is evolving. CBN wheels are very recent, especially those compatable with the Tormek. Stig is quite correct that these wheels are single grit. I have seen them in 80 and 180 grits. Purchasing both would cost almost the cost of a new T7. Within their limited scope, they do offer some benefits. I can see where they might excel at sharpening planar blades with the Tormek. Even a Tormek junkie like me would have to think long and hard before investing that kind of money. If I had a business which included sharpening a lot of planar and jointer blades, I would certainly obtain at least one CBN grinding wheel. Not having to refresh or dress the grinding wheel during the middle of grinding planar blades seems a notable advantage.

They might be very efficient for reshaping turning tools. They are the same width as the T4 wheels (1 ½" or 40mm). As Rob noted, that is a constraint compared with the T7 wheels at 2" or 50mm. Again, if I had a sharpening business where I was reshaping many turning tools, a CBN wheel might be a good investment. With the new EZYlock shaft, switching wheels for a final finer cut is easy to do. However, spending that much money to reshape perhaps four to six turning tools at most hardly seems cost efficient.

I believe the Tormek is a very versatile tool in its present configuration. I also believe it is capable of much more versatility. Ten years ago, who would have thought of sharpening  four facet drill bits with a Tormek? Six years ago, we were still sharpening small knives handheld. Now we have a choice of the Tormek small knife tool or Herman's jig. We are presently seeing more potential than knives and machetes with Herman's jig. Both are useful with slightly different focus points.  Evolution continues.

I believe this question of CBN wheels is an example of the capabilities of the Tormek  going beyond the scope of accessories which are profitable to market in reasonable quantities. I am pleased that we have such a well designed and built machine on which to base this growth.

Ken

[Rob]

I've been rather sheltered from real life while all this family illness has been going on....CBN...what's the deal with these wheels then?  They sound very hard and very abrasive from your description Ken.

[Ken S]

Sorry I can not offer much help, Rob. I am still in the learning stage about CBN. I gather it is slightly less hard than diamond and perhaps less brittle. Either the 80 or 180 single grit wheels would be more coarse than the Tormek SG wheel.

Ken

[Rob]

OK thanks Ken :-)

[grepper]

Much safer.  They won't crack, explode or chip.  Excellent for cut-off wheels.
Cleaner.  No stone dust.  (A clean water trough)
Higher thermal conductivity.  ~55% better than traditional wheels.
Tools remain cool after grinding.  No more blue blades. Slow speed grinding not necessary.
No change in wheel diameter over life of wheel.
Consistent abrasive across the surface of the wheel.  Higher precision grinding.
Surface stays flat. 
Perfectly flat side wheel grinding.
Can be plated onto almost any shaped wheel.  Thin cup wheels for example.
No down time for dressing/conditioning.
Fast material removal of HSS.
Reduced vibration.  No balancing required for high speed cutting.
Reduced time spent grinding.  Saves labor costs.  Increased production.
Almost no sparking.
4X harder than AO.  Almost as hard as diamond.
Doesn't clog or glaze like regular wheels when used on HSS, but may clog with soft steel.
Does not react chemically with steel like diamond wheels do.
Longevity.  20% - 50% cost reduction over regular wheels.
Won't break if dropped.
Very light pressure is needed when grinding.
Not effected by solvents.

For Tormek:
http://www.cwsonline.com.au/shop/item/woodcut-cbn-wheel-250mm-x-40mm-x-180g

Watch.  No sparks!
https://www.youtube.com/watch?v=urM-5P8_t4g

[Rob]

They look impressive "IF" we believe all the hyperbole on the website. Do we?  Has anyone used one?  Do they really NEVER go off flat even with repeated grinding of bowl gouges made from HSS.  I appreciate the CBN is harder than the HSS but even so....diamond stones get dished eventually over time don't they?

So my next question would be myth versus reality based on folks real experience. If they stand up to the brochure then they certainly sound amazing.  Life experience to date would make me a tad suspicious of such "perfection" claims. Anyone used them?

[grepper]

I have not used one, but it seems it is true, and that they last for years.

They are made by applying a single layer of abrasive with electroless nickel plating (very tough stuff) on super hard steel.  Steel won't dish.  For example, they use them for "precision finish grinding of hardened gears after heat treat".

"Holding profile tolerances of 0.0001" to 0.0002" (one to two ten-thousandths of an inch) is routine
for our wheels, and we have produced profile tolerances of 0.00005" (50 millionths of an inch) for some aircraft gear
applications,"

http://www.gleason.com/uploads//PlatingFacArticle_pdf_english.pdf

[grepper]

"There are two types. One is a mix of abrasive and a bonding agent, that is applied to an aluminum hub in a layer that is about 3/16 inch thick. The other type is a machined steel hub with the abrasive material electroplated to the surface of the wheel."

"With the matrix bond type, there is tiny wear factor involved as the matrix is not as hard as the abrasive materials. They do develop a tiny amount of run out over a year or so of heavy use."

"Electroplated wheels never change size or shape"

Reed's Woodworking:
http://www.robohippy.net/featured-article/