I want to conclude my CBN tests with the Tormek. The purpose of these tests was to determine if using CBN grinding wheels on the Tormek, wet and/or dry, was possible and practical.
In a nutshell, I was pleased with the results. I found the CBN wheels useful adjunct units for the Tormek for specific operations. CBN made reshaping turning tools pleasant instead of a dreaded chore. I was unable to obtain sample planer blades, however, I am convinced that CBN would make sharpening planer blades much more efficient. CBN does not glaze with tool steel. The wheels do not need to be dressed or trued.
During my standard five minute test grinding a metal lathe tool bit mounted in the square edge jig, I found the CBN wheels cut as well at the end of the test as in the beginning. This was a marked improvement over the standard wheels, especially the SB blackstone.
I would consider a CBN wheel essential for anyone sharpening planer blades. I would consider them highly desirable for turners, especially those who do a lot of reshaping.
The 180 grit CBN wheel did an adequate job with initial sharpening of wood chisels, however, I prefer the standard Tormek SG wheel. It is designed for high carbon steel. I like the feel of the grinding with the SG. The SG. Like the SB, can be graded to be coarse or fine. The CBN wheels are single grit. I did notice a sharpness difference in the 80 grit wheel depending on whether it was used grinding into or away from the tool. Into the tool, the BESS reading was 495. Grinding away produced a BESS reading of 400, just about the same as the 180 grit made grinding into the tool. Lower BESS readings mean sharper edges. The "gold standard" reading with BESS, 50, is typical for a new double edge razor blade. Grinding away took considerably longer. I would use CBN wheels grinding into the wheel for heavy grinding.
Although the CBN wheels cannot be graded like the Tormek wheels, going directly from the wheel to the leather honing wheel produced a BESS reading of 130, surprisingly respectable, not quite a match for the 100 obtained with the SG, but close.
The CBN wheels ran surprisingly cool with the Tormek. Even with dry grinding to reshape a turning gouge, the tool was warm, but not hot. I would not consider wet grinding necessary to control heat. Sparks did not appear to be a problem.
The grinding dust from CBN wheels is only tool steel. There is no abrasive grinding dust from the wheel. When used wet, it is entirely contained, as it is with any Tormek wheel. When used dry, it is easily controlled with magnets.
One noticeable characteristic with CBN wheels is being much coarser when new. This soon wears off and the wheel becomes its intended grit. First use should be reserved for a major grinding project, which it will do well.
I did not notice any real difference in noise compared with conventional grinding wheels.
The three CBN wheels I used were steel D-Way wheels (dwaytools.com) One was 80 grit and ten inch diameter. The other two were 180 grit, one eight inch diameter and one ten inch diameter. The two ten inch wheels were used and generously provided by Dave Schweitzer of D-Way. I initially purchased the eight inch wheel from D-Way for my T4. I decided to purchase the two ten inch wheels at the end of the test.
When used wet, I encountered a rust problem with plain water. Adding Honerite Gold rust preventing additive solved this problem. Honerite Gold (not the same as Honerite) is diluted one part to twenty five parts with water. I used the following amounts. With the T4, 75ml water with 3ml Honerite Gold. With the T8, 125 ml water 5 ml HG. With the T7, 200 ml water 8 ml HG
The CBN wheels do not absorb water.
Both eight inch and ten inch CBN wheels fit directly with the Tormek. In fact the eight inch also fits directly with the larger size T7 and T8 The eight inch wheel used wet with the T8 required only 225ml water with 9 ml HG. Using the eight inch CBN wheel would be a possibility for someone who also wanted an eight inch dry grinder. (I question the practicality of this arrangement.)
Whenever I drained the water trough and stored the Tormek, I sprayed a protective covering of WD40 on the steel bushing and wiped the sides and bore of the wheel with WD-40 or light oil.
With the 180 grit mounted dry, the Tormek becomes a very quick touch up grinder.
The D Way wheels are 1 1/2", or approximately 38mm. While this is narrower than the standard 50mm of the 250mm Tormek wheels, I had no trouble quickly adapting. It was not a problem.
In summation, while the Tormek SG remains my "go to" wheel, for turners and planer blade sharpeners, a CBN wheel is a serious candidate for the second wheel. CBN makes the Tormek, a fine sharpening system, into a very respectable reshaping machine.
Ken
So, Ken; I only sharpen knives and chisels at this point in my life...................far, far more knives than chisels. Would you think that I needed a CBN wheel? thanx
Jeff,
Good question. In general, I would say no. Most knives are carbon steel, of something similar. Tormek users have been sharpening conventional knives successfully with the SG for decades. I would include chisels with this group.
OBR has posted about working very busy Saturday mornings, where the sharpening volume would make truing and dressing difficult. In that case, I would give a finer grit, say 600, CBN wheel serious consideration. There are also some more exotic knives which are too hard for conventional grinding wheels. These would be another CBN situation.
CBN wheels in 80 and 180 grit are prilarily marketed for turners who need to reshape their tools occasionally or often.
Ken
Thank you for the completion of the saga (said tongue-in-cheek), Ken. :) I appreciate the time and the effort you spent! It is great information to have.
You are most welcome, Eldon. I try to make sure the forum gets good information.
Ken
Excellent all round research Ken. Very kind of you to go to such effort and cost and then share your findings in this way. You truly ARE a hero member :-)
Your findings are also very relevant to some of my woodworking activities so its very useful and topical for my situation and helps to extend the value of the Tormek for me.
Thanks again my friend.
De nada, amigo.
Ken
I think the fact that you found them great for turning tools and think they will be good for planer blades, kind of self explains why we haven't seen more posters of that kind on the forum. Where when we first discussed why we hadn't seen this here, most of the stuff I found, was in the turning section of woodworking forums, with active turners who spend more time doing charity stuff (wounded warrior/patriot pens, etc), then want to spend sharpening.
Same tools, just different goals. This is a good forum to learn, but don't be afraid to go outside our comfort zones for learning. :)
SADW,
Your points are well taken; I agree. "This is a good forum to learn, but don't be afraid to go outside our comfort zones for learning. :)" For the record, I found numerous posts on CBN wheels on other sources and forums, especially the sawmill creek forum.I recently became a member of sawmill creek, and posted perhaps three times. Except for that, I do not post on other forums. My constraint is time. Incidentally, Jeff Farris posted on several forums.
I regularly search other sources of Tormek and sharpening related information, usually several times a week. The CBN posts are almost exclusively turning oriented, and generally with dry grinders. I have no prejudice against other sharpening methods or for using non Tormek made accessories with my Tormek.
Among the information I found on other sources, I did not find anything which offered practical advice for using CBN wheels with the Tormek, or reasons not to use them with the Tormek. I tried to approach the subject in an unbiased manner. Having the name "Tormek" of an accessory does not get an automatic approval from me, nor does an accessory not named "Tormek" have any harder judging standards. In the case of CBN wheels, I realize that they represent a substantial investment for a Tormek owner. I hope to provide our members with a better starting point to make their own independent judgements.
Ken
Ken,
Thanks for the well and thorow full report.
I just "liberated" a ten milliliter liquid medicine scoop my granddaughter had used with cough syrup. It says Kroger Pharmacy (a local chain grocery store, although most pharmacies should have them). It should work very well with Honerite Gold.
Ken
Also much thanks for this fine report Ken, but there's one thing I don't get.
Why is it detrimental to use CBN on Carbon Steel? Is Wheel damaged some how, or what? How about stainless steel blades?
Sure is appealing to have wheel that never has to be trued and lasts forever
Larcal,
Welcome to the forum. You have asked two very good questions.
Not being a metalirgist, I may have used a confusing term in "carbon steel". Mild, unhardened steel would be more accurate. CBN is designed primarily to grind harder steel alloys, such as high speed steel. As part of my testing, I ground several Irwin Blue Chip chisels. These would be considered high carbon steel. They are also heat treated. They are typical of the traditional steel used for woodworking tools and knives. Due to the fine grain structure of the heat treated steel, high carbon steel tools can be sharpened to a higher degree of sharpness than A2, HSS or carbide steel. The trade off is this high degree of sharpness does not last, and the tool must be frequently sharpened.
I had no problem grinding several high carbon chusels with my CBN wheels. At last count, I have around eight 3/4" Irwin Blue Chip chisels. Having this many let me compare the surface of bevels ground with different grits.
The loading or clogging occurs only with very soft steel. This is essentially the same problem conventional grind stone have when someone tries to grind aluminum. The fix is easy, just grind a piece of hardened steel such as hss. It will unclog the wheel. You should watch the you tubes made by D-Way Tools. Dave Schweitzer demonstrates this declogging. I found the D-Way videos very informstive. They were my major source of information for my testing.
I also tested a garden variety "stain resistant" kitchen knife. An 80 grit wheel will give your knife edge all the tooth you want! To my surprise, the 80 grit wheel followed directly by the Tormek leather honing wheel loaded with the standard Tormek honing compound gave a surprisingly respectable edge. I should note that this edge was almost, but not quite as sharp as the traditional Tormek SG-250 technique.
I would not claim that CBN wheels last "forever". They do last a very long time. I found the initial excessive coarseness broke in quickly. I expect that whoever eventually purchases my lightly used wheels from my estate will get a lot of use from them. I would expect that someone like Curt, who gets a year out og an SB-250, will eventually need to replace a CBN wheel. Longevity aside, the main advantage for someone like Curt is that the wheel will not need dressing and truing.
There is a flip side to this longevity. I lent my 180 grit wheel to Curt to try. He noticed a slight high spot. I had not noticed the high spot; Curt is a far more experienced sharpener than I am. With a conventional Tormek wheel, the next wheel truing would eliminate the high spot. With a CBN wheel, the slight high spot will be there "forever". In fairness to D-Way, Dave generously loaned me two older wheels. My original purpose was to test how the wheels performed when used wet. (The steel wheels and steel reducing bushing work fine wet as long as Honerite Gold is added to the water and the wheels are left dry. I wipe on a bit of oil before storing them.
Dave offered to sell me the wheels at a generous used price. From my limited testing, the two used wheels seemed to cut as well as the new eight inch wheel I purchased initially from D-Way. A CBN wheel on a T4 is a lot of firepower in a compact package!
I have a DMT diamond flat plate. It is a marvel for flattening water stones and India oil stones. I made the mistake of flattening a Carborundum stone with it. It flattened the stone, but lost much of its useful life in the process. It still works with water stones, but the process takes longer. If diamond wears, I am sure CBN will wear, also.
I think a turner who does a lot of reshaping should have a CBN wheel for his Tormek. I found it made that lengthy chore pleasant. Although I have not tried it, I am convinced that CBN is the answer for planer blades. I do not think CBN should be the only wheel for a general Tormek sharpener. For everyday sharpening, like woodworking tools and kitchen knives, the SG is still my go to wheel.
Ken
We've been using CBN wheels for over half a year, on a few hundred knives by now.
Can only confirm what Ken has said above.
The leaflet that comes with CBN wheels warns against high carbon steels, however, carbide type matters.
With conventionally cast high carbon steel, e.g. 1095 (Carbon 0.95%), and those that Ken calls "mild", the ground metal fills in the CBN pores, and the wheel grinds worse and slower.
But as soon as the steel is stainless, will it be mainstream (chromium carbides), or high-end homogeneous powder-metallurgy alloys (vanadium carbides, tungsten, molybdenum) - works perfect on CBN even when Carbon contents nears 2% (e.g. M390 or S290), with all the advantages the CBN can offer over the stone wheels.
larcal, feel free to ask more questions if any left.
Excellent post, Wootz!
Ken
Quote from: wootz on September 03, 2017, 10:37:35 PM
We've been using CBN wheels for over half a year, on a few hundred knives by now.
Do you have a grit preference? (The.... If you could only buy one.... question).
And do you finish on a CBN (prior to stropping if any), or switch to a waterstone? (Guess the easier question... what's your "CBN use" procedure)?
Thanks.
Quote from: cbwx34 on September 05, 2017, 04:45:32 PM
Do you have a grit preference? (The.... If you could only buy one.... question).
Speaking of knife sharpening (not woodturner' tools), if you could only buy one CBN wheel, get #1000, and not necessarily the 10" Tormek-ready; cheaper 8" CBN wheels work fine on both T4 and T7/8/2000, you only need a bushing to fit the Tormek shaft - the bushing specs are here:
http://knifegrinders.com.au/05Equipment_CBN.htm (http://knifegrinders.com.au/05Equipment_CBN.htm)
On the CBN wheel #1000, we can set edge on most of the knives.
With the grossly dull knives, you can set bevel on rough SG or SB, then continue on #1000.
Quote from: cbwx34 on September 05, 2017, 04:45:32 PM
And do you finish on a CBN (prior to stropping if any), or switch to a waterstone?
The edge you get on #1000 can be deburred and finished on the Tormek leather wheel with a honing compound; we do it on paper wheels.
For regular knives you do not need a finer grit in between.
Safe queens go through a combination of SJ and paper wheels.
Quote from: cbwx34 on September 05, 2017, 04:45:32 PM
... what's your "CBN use" procedure?
It is in the "Sharpening Procedures" section on our website, e.g. see there "Stainless steels, mainstream" or "Tool and high-end steels" etc
http://knifegrinders.com.au/06Procedures.htm (http://knifegrinders.com.au/06Procedures.htm)
Ah.... very cool. Thanks! :)
Thank you Ken and Wootz for your thoughtful answers.
Have partially looked over Dave Schweitzers videos but so far seen no mention of the clogging issue and it's solution but will keep looking. Guess I'd like to ask if either of you have tried declogging by his method and if it does in fact work and is fairly easy?
And there is this possible discrepancy in the way I read your experience if you guys would care to comment.
Ken says the clogging only happens with "mild steel", a term usually applied to low carbon steel up to max carbon of .3% that can not be heat treated. He has no problem with high carbon heat treated steel chisels that are probably in the 1% or more carbon camp but do not, I'm guessing) have any of the special additions like tungsten, molybdenum.
While you, Wootz, seem to experience that it is necessary to have these "metalurgical alloys" to avoid clogging and that any normal high carbon, even the very high 2% ones, will present problems without them. And as you say, even the CBN leaflet warns against high carbon.
So is interesting as to why Ken has no problem, or I'm misinterpreting this some how
Glad to see that you both agree Stainless steel blades are fine on CBN.
Other good and interesting points made in both posts
We saw CBN wheel performance decrease after conventional rusting steels, both low and high carbon (e.g. 1095), on a couple of occasions, and 1095 clogged worse.
On the other hand, Japanese high carbon, well tempered hard steel kitchen knives cause no problem, similar to Ken's chisel.
So it is not only about Carbon contents, go guess. Temper might matter, as Ken suggested.
Solution in the leaflet is to wash in kerosene with a brush - so as soon as we noticed that, we ran the CBN wheel with the Tormek water trough filled with Turpentine, and brushed it with a tooth brush... This saved the wheel, but turpentine discoloured the trough.
Given their cost, and the trouble of cleaning, we generally avoid sharpening rusting steels on the CBN wheels, so far so good.
Excellent post, Wootz. CBN is designed for hard steels. The SG is designed for carbon steel. I don't think of either as a universal wheel, although the SG was the only wheel for the Tormek for many years.
Ken
Tormek-ready CBN Wheels from WoodturnersWonders for less than the cost of stone wheel, all grits. Haven't tried them myself yet, but affordability is a true breakthrough.
https://woodturnerswonders.com/collections/spartan-affordable-cbn-wheel-1/products/spartan-10-cbn-wheel-5-8-arbor (https://woodturnerswonders.com/collections/spartan-affordable-cbn-wheel-1/products/spartan-10-cbn-wheel-5-8-arbor)
My pet peeve with this company is not their products. I have never used them, so I have nothing negative to say about the wheels. My pet peeve is how they are photographed. The edges look like they taper. They should be square with the sides of the wheel. I believe they are, however, one would not know that from looking at their photographs.
Good commercial photographers solved this problem the better part of a century ago. The answer is to use a longer lens and make the photograph from farther away to flatten the perspective. Ring photographers deal with the same possible distortion, as do portrait photographers. How many times have we seen a portrait shot too close, so that the subject's nose appears too large.
Grumble, grumble. The photo just hit a pet peeve.
Ken
So true about the photo, Ken, that I even asked Ken Rizza at the WoodturnesWonders, though about other Spartan wheel, and he assured they are square.
But you never know till get one yourself...
Is that a plastic wheel? No rust?
How is the CBN attached? Electroplated to an aluminum ring around the plastic wheel? Steel ring around plastic wheel (rust?)?
If it is a plastic wheel with a plastic hub, any issues with hub wear? I know some folks remove the wheel after each use. ;)
The wheel surface is electroplated CBN on steel, and center is made of nylon - the latter drops the cost.
I use CBN wheels wet or dry. I think the water mess problem with Tormek grinding is overhype and mostly a result of sloppy technique. No one seems to mention the mess of dry grinding dust. Minor spillage of water is easily controlled and contained. Dry grinding metal dust may not be so easy to contain.
I use Honerite Gold at the standard dilution of 1:25 with water. That and careful drying with a light coat of oil at the end of the session has cured the rust problem for me.
Personally, I like the idea of inexpensive CBN wheels for turners. A coarse CBN wheel would make quick work of reshaping. Do a quick change with the EZYlock to the SG for sharpening. You have the best of both worlds.
Wheel wear with nylon? I would expect more wear than with steel. However, the Tormek bushings are nylon, and work fine. Part of our thinking is back in the high speed dry grinder era. I would expect sealed steel bearings in a Baldor grinder. It lives in a much more stressful environment. I suspect the nylon bushing area of the wheels will probably last as long as the CBN grit. At the price, they can be replaced more often, if needed. (If one is wearing out wheels with any grinder in business, the revenue produced should certainly cover new wheels as needed.)
Ken
I asked our Australian woodworkers what steels should be avoided on CBN wheels and they said unhardened only.
They gave me a long list of tool and knife steels they grind on CBN wheels, but in one word - any steel is OK except poorly hardened - the latter will gum up the grit. Tungsten carbide is another exception, but for a different reason - better done on diamonds.
Well, we have to conclude that the manufacturer's leaflet coming with the CBN wheels is incorrect in saying that high carbon steels should be avoided.
BTW, Ken Rizza at the WoodturnesWonders has sent me a 10" Tormek-ready Spartan CBN wheel, and delivered it would cost me less than a stone wheel bought locally. If it is as flat and square and round as promised, you won't want a stone wheel any more.
The Spartan CBN wheel won't be cooling as well on regular bench grinders as its fully aluminum counterparts, but that has no bearing on the low-speed Tormek.
For a new generation of Tormekers, the problem will be to find a Tormek machine on sale stripped of the stock wheel.
"If it is as flat and square and round as promised, you won't need a stone wheel anymore."
That's a lot of ifs. Not only that, those ifs cannot be easily corrected by routine maintenance with the TT-50 Truing Tool. And, unlike the SG-250 stone wheel, CBN (and diamond) wheels are single grit. Putting together a multigrit sharpening system with CBN is not difficult, however, it requires purchasing several wheels.
I have three CBN and one diamond wheels. Each has a purpose, and fulfills that purpose well. Like my modified Norton 3X wheels, most of the CBN wheels are coarser grits (80 and 180) primarily for reshaping woodworking tools. They do this very well and quickly. I think a 180 grit CBN wheel would be a good investment for an active turner. I would recommend switching to a stone wheel and leather honing wheel to complete the sharpening, especially before making the finish cuts.
For rough grinding of high speed steel, the SG-250 is no match for a CBN wheel. For harder steels, it is no match for the SB-250, CBN or diamond. For a highly polished edge, it is no match for the
SJ-250. The SG-250 is primarily designed for high carbon steel. It performs this function very well. Unlike the more exotic wheels, when it wears, it is easily retrued. It can be graded to function as several grits. It can sharpen high speed steel. HSS is not its forté, however, until ten years ago, it was the only wheel available for the Tormek and did trooper service. While it does not match the Tormek SJ-250 4000 grit stone for the ultimate, highly polished edge, it comes reasonably close without the several hundred dollar additional cost.
I have read several reports of CBN wheels wearing out of flat and square. My ten inch 180 grit CBN wheel is slightly out of round. It still functions. As I recall, Wootz, your original CBN wheel soon wore out of flat.
Please do not misunderstand me. I am a proponent of CBN wheels. They have some significant advantages for some Tormek users. As they evolve, they will be a larger part of kit for Tormek users. They are certainly long lasting. For the average Tormek home user, this may be a lifetime. I would not say they last forever. With the right grit, they may work very well for a professional knife sharpener. Please note that even the T2, designed for simplicity of operation with a 600 grit diamond wheel, has an optional second (320 grit) diamond wheel. In my home workshop, trying a suggestion by Sharpen a Dull Wit, I ground a knife into a "cake knife" by removing the bevels. I then resharpened it with the T2 and 600 grit wheel. Sixteen double passes on each bevel did the job. In my home shop environment, this amount of time is no problem. For a professional, this would be unacceptable. A busy sharpener would switch to a second, coarser wheel for initial sharpening. (Ordinarily I would have used the SG or SB stones graded coarse.
For a garden variety Tormek user like me, I believe the standard issue SG wheel is still the most practical, cost efficient choice for a one wheel shop. For those who might read this in the future, I would add that the Tormek is an innovative, evolving and expanding technology. At some point, CBN, diamond, or something else may become the standard "stone". Until that time, I believe the obituary for the stone wheel is premature.
Ken
I'm still a bit confused... ??? maybe this was answered somewhere, but why CBN over diamond? Going by what I've read on the interweb... diamond is generally cheaper, and CBN was used only where diamond couldn't be (usually when heat is an issue, if I understand it), and that diamond in general performed better. Yet all the aftermarket stones (with the exception of the new T-2 stones), seem to be CBN.
So, what's the reason(s) for CBN over diamond?
Quote from: cbwx34 on October 06, 2017, 09:40:14 PM
I'm still a bit confused... ??? maybe this was answered somewhere, but why CBN over diamond? Going by what I've read on the interweb... diamond is generally cheaper, and CBN was used only where diamond couldn't be (usually when heat is an issue, if I understand it), and that diamond in general performed better. Yet all the aftermarket stones (with the exception of the new T-2 stones), seem to be CBN.
So, what's the reason(s) for CBN over diamond?
Not that puzzling if you imagine yourself an owner of a factory producing grinding wheels, and streamlining profits is your major concern.
You know that CBN has higher heat and impact resistance than diamonds - and this is important for high RPM grinders which are your principal consumer base. With them in view, you commission a CBN technology, and as a side-line you also make wheels for Tormek-like slow grinders. Having an additional diamond wheels line for slow rotary grinders just isn't that profitable, i guess.
What has been said in this thread, is better read together with Curt's thread https://forum.tormek.com/index.php?topic=3259.0 (https://forum.tormek.com/index.php?topic=3259.0)
All read and thought over, hardly can it be summarised better than Ken did a post above.
Quote from: wootz on October 06, 2017, 10:33:28 PM
Not that puzzling if you imagine yourself an owner of a factory producing grinding wheels, and streamlining profits is your major concern.
You know that CBN has higher heat and impact resistance than diamonds - and this is important for high RPM grinders which are your principal consumer base. With them in view, you commission a CBN technology, and as a side-line you also make wheels for Tormek-like slow grinders. Having an additional diamond wheels line for slow rotary grinders just isn't that profitable, i guess.
What has been said in this thread, is better read together with Curt's thread https://forum.tormek.com/index.php?topic=3259.0 (https://forum.tormek.com/index.php?topic=3259.0)
All read and thought over, hardly can it be summarised better than Ken did a post above.
Makes sense.
Hopefully, Curt (OBR) will post a followup in that other thread.
Thanks, Wootz. You have been the original forum pioneer with CBN. Like you, I hope Curt (OBR) will continue posting on his CBN journey. We all benefit from having posts from different backgrounds. You, with a high end sharpening service; Curt as a high energy farmers market weekend warrior, and me as a curious home shop sharpener.
From what I have learned, if CBN works better at high speeds, and diamond wheels are less costly to manufacture, I think Tormek shows good engineering by choosing the less costly product which suits the slow speed Tormek. I was surprised at the cost of the Tormek diamond wheel. The prices seem very reasonable to me. Not cheap, but fair. Tormek has chosen a product ideally suited to the Tormek machines at a reasonable price.
I would be curious to know the reaction when Tormek first introduced the man made SG grinding wheel as an alternative to the locally mined natural stone. The SG stone is coarser than the nstural stone. My uninformed guess is this was the original impetus for the stone grader.
Ken
I haven't read any further, but one CBN wheel manufacturer claims that the pure carbon in diamond wheels forms carbides with the other elements in steel, destroying the diamonds. http://www.optigrind.com/page_2538178.html (http://www.optigrind.com/page_2538178.html)
Mike
Mike,
I have not found definite proof, however, I suspect the carbon problem is from the high heat produced in high speed grinding. The slow speed (approximately 100 RPM) of the Tormek is very different than the 1725 to 3450 RPM world of dry grinders.
I am glad you brought up the question. We need more documentation. The costs of designing, research testing, and manufacturing the T2 with the diamond wheel must be substantial. I can not imagine Tormek choosing diamond for the wheel if there was a carbon/carbide problem which effected grinding at Tormek speeds. I wish Tormek would share more of its decision process in choosing diamond.
Ken
Hi,
This happens only with high-speed grinders. CBN wheels are designed to mainly be used on bench-grinders.
Sincerely,
Stig
Quote from: AKMike on October 08, 2017, 02:58:12 AM
I haven't read any further, but one CBN wheel manufacturer claims that the pure carbon in diamond wheels forms carbides with the other elements in steel, destroying the diamonds. http://www.optigrind.com/page_2538178.html (http://www.optigrind.com/page_2538178.html)
Mike
This discussion of CBN and diamond wheels illustrates my idea about trying to apply high speed dry grinding thinking to the Tormek.
I have downloaded the instruction booklets of the clones. The safety portions give away the high speed dry grinding thinking. A grinding wheel turning at 3450 RPM requires more stringent safety precautions than a wheel spinning at 100 RPM. That is why high speed grinders require guards, spark guards, eye shields and cooling buckets. (That same dry grinding thinking, and cost, are why clones are still using rust prone regular shafts eleven years after Tormek converted to stainless steel.)
Past posts have suggested that the Tormek could be improved by using sealed bearings instead of nylon bushings. This is another example of high speed dry grinding thinking. In a low speed, wet environment, the nylon bushings do not rust. An older non stainless shaft and nut may be solidly connected with the grinding wheel by rust, especially from poor housekeeping or lack of yearly regreasing. I have never heard of a shaft freezing to a nylon bushing. How many of us have old SuperGrinds with shafts rusted tight to the grinding wheel, but otherwise working perfectly?
Much of the consumer grinding world thinks in high speed dry terms. It is important to recognize this thought prejudice.
Ken
Quote from: wootz on September 13, 2017, 01:12:15 AM
Tormek-ready CBN Wheels from WoodturnersWonders for less than the cost of stone wheel, all grits. Haven't tried them myself yet, but affordability is a true breakthrough.
https://woodturnerswonders.com/collections/spartan-affordable-cbn-wheel-1/products/spartan-10-cbn-wheel-5-8-arbor (https://woodturnerswonders.com/collections/spartan-affordable-cbn-wheel-1/products/spartan-10-cbn-wheel-5-8-arbor)
Today had first customer folder ground on this wheel, a Benchmade Osborne S30V - the wheel is all-round perfect – flat, square, and round.
The best flatness of all CBN wheels I have. Affordability is a true breakthrough.
Challenge with this particular blade was that it came with an uneven bevel out of the box, by 1mm higher at the tip:
(http://knifegrinders.com.au/photos/Osborne_before.JPG)
Fixing defects like that is demanding to the flatness of the wheel - the result is pretty good:
(http://knifegrinders.com.au/photos/Osborne_after.JPG)
Having ground the bevel on the Spartan CBN #1000 wheel, refined the edge on a sequence of paper wheels from 5 micron diamonds, down to 0.5 micron diamonds.
Final edge sharpness is 45 BESS, hair-whittling.
Can definitely recommend the Spartan CBN wheels.
Which sharpness tester are you using Mr. Wootz?
PT50 1st issue in the workshop.
Have to admit, Mr. Grepper, I still learn a lot from your posts on the BESS forum
Quote from: wootz on October 18, 2017, 08:25:25 AM
Having ground the bevel on the Spartan CBN #1000 wheel, refined the edge on a sequence of paper wheels from 5 micron diamonds, down to 0.5 micron diamonds.
Final edge sharpness is 45 BESS, hair-whittling.
Can definitely recommend the Spartan CBN wheels.
Wootz, your BESS sharpness 45 gf is an excellent result!
Following the BESS definition it means that your edge is as sharp (and also as thin) as a standard DE razor blade. The apex width is surely in the submicron region.
Based on prof. Verhoeven measurements the edge width of Gillette DE razor blade was about 0.3 microns.
J.F.Sackman paper reported that the edge width of Wilkinson DE razor blade was about 0.1 micron.
Jan
True, that's the best reading for the S30V steel I ever got, usually I get a score between 60-80 - that blade must have been very well tempered.
Not sure if you guys have played with them yourselves, but both the Gillette & Wilkinson DE razors score anywhere between 25 to 35 on the PT50 and PT50B with little consistency. Although in the specs the PT50 & PT50B resolution is at +/- 5, it is true in the over 50 segment of the BESS scale; these instruments lowest meaningful reading is somewhere at 30, and you cannot trust any score under.
Not that it is written somewhere or Mike told me - just came obvious to me from trying razor edges.
It is therefore only possible to say more or less confidently that the edge apex width is in the 0.2 micron range where the score is under 80-90, and that it is probably in the vicinity of 0.1 micron, where the score is 20-60.
For true submicron measurements, a PT50A or KN100 is needed.
I realise that these notes are not pertinent in here, just haven't registered at the BESS forum yet, still in the reading mode there.
Recently ToddS on bladeforums.com has shown perfect SEM images of different brands of razor blades. He claims that the average edge width is about 0.1 micron.
This is in full agreement with Sackman paper, A Close Shave, published in Physics in Technology, vol. 9, already in 1978!
Jan
The 45 gf reading is very impressive, Mr. wootz! Excellent job of sharpening there. ;)
Are you using test clips or the media holder on the PT50?
I'm surprised by that 25-35 gf reading on the Gellette's. If memory serves, that's sharper than your average Feather DE blade.
I learn from you too Mr. wootz. One big happy family. :)
... spooled certified media.
What surprises you, I believe only tells us that the PT50 and PT50B are unreliable in the lower range of the BESS scale under 50.
All our edges score between 50 and 90 on PT50, i.e. between 0.1 and 0.2 micron, and there is nothing amazing about it. Miracles aren't allowed in my workshop - only consistent angle is while sharpening and deburring.
Absolute angle value is of no concern, but maintaining the same angle through the sharpening session is.
Steel type and temper bring the edge closer to either 50 or 90.
Quote from: Jan on October 19, 2017, 02:33:43 PM
Quote from: wootz on October 18, 2017, 08:25:25 AM
Having ground the bevel on the Spartan CBN #1000 wheel, refined the edge on a sequence of paper wheels from 5 micron diamonds, down to 0.5 micron diamonds.
Final edge sharpness is 45 BESS, hair-whittling.
Can definitely recommend the Spartan CBN wheels.
Wootz, your BESS sharpness 45 gf is an excellent result!
Following the BESS definition it means that your edge is as sharp (and also as thin) as a standard DE razor blade. The apex width is surely in the submicron region.
Based on prof. Verhoeven measurements the edge width of Gillette DE razor blade was about 0.3 microns.
J.F.Sackman paper reported that the edge width of Wilkinson DE razor blade was about 0.1 micron.
Jan
Jan, it is good for prof. Verhoeven he had retired before Gillette could read his publication.
Gillette would have destroyed him for saying loud their razors are 3 times thicker than competitor's :-\
In the miniscule world of Angstroms and nanometers, that difference is larger than from your Czech home to Tormek headquarters in Sweden.
Though that knife score on the PT50 instrument we use in our workshop is in the range of scores showed for razors by the study at https://www.refinedshave.com (https://www.refinedshave.com) - it should not be interpreted as equal because our instrument is just not good enough for that range; its readings cannot be extrapolated to the razor readings taken by the PT50A used in that study.
Well, we should not really go on our BESS chat here, I am registering as KnifeGrinders at the BESS forum today, and we better continue there.
EDIT: Posted at http://www.bessex.com/forum/showthread.php?tid=186
Quote from: wootz on October 21, 2017, 12:53:00 AM
Jan, it is good for prof. Verhoeven he had retired before Gillette could read his publication.
Gillette would have destroyed him for saying loud their razors are 3 times thicker than competitor's :-\
In the miniscule world of Angstroms and nanometers, that difference is larger than from your Czech home to Tormek headquarters in Sweden.
Can you explain this? The contempt shown here is inappropriate. Prof verhoeven has made a significant contribution to knowledge about grinding. We use that knowledge and develop it further. We must be aware that we are on the shoulders of this kind of pioneers.
I do not believe Jan intended any contempt or disrespect for Professor Verhoevev or his work. We often ascribe too much significance to numbers. As I have not shaved for twenty five years, my information may be outdated. I used Gillette blades for many years with no complaints. I had no idea about the micron size of their edges. They gave me a good shave as I presume they still do.
There are people who, with absolutely no concept of microns in shaving, might conclude that Gillette blades were inferior due to a higher micron measurement. We are obsssed with numbers in advertising which we do not understand. I remember news reports in the past comparing the number of times the nuclear arsenals of differents could destroy the earth. In hindsight, any number greater than one is overkill. Advertising and marketing convinces us to purchase far more than we need. Any company, including Gillette, would be concerned with any number, no matter how insignificant, which might make their product seem inferior.
I hope the dialogue on this forums, and the use of BESS readings will help advance our knowledge of practical measurements in our knowledge of sharpness.
Ken
Quote from: Dutchman on October 21, 2017, 01:01:52 PM
Quote from: wootz on October 21, 2017, 12:53:00 AM
Jan, it is good for prof. Verhoeven he had retired before Gillette could read his publication.
Gillette would have destroyed him for saying loud their razors are 3 times thicker than competitor's :-\
In the miniscule world of Angstroms and nanometers, that difference is larger than from your Czech home to Tormek headquarters in Sweden.
Can you explain this? The contempt shown here is inappropriate. Prof verhoeven has made a significant contribution to knowledge about grinding. We use that knowledge and develop it further. We must be aware that we are on the shoulders of this kind of pioneers.
It was meant to be a humor, not contempt.
Actually, Verhoeven estimated Gillette DE razor edge width of 0.35-0.45 micron (page 6).
Doesn't that much difference with the Sackman's estimate of 0.1 micron for a Wilkinson razor surprise you as much as it surprised me?
As a matter of fact, almost 2 years ago Mike Brubacher, the BESS edge sharpness tester inventor, told me that Verhoeven couldn't be right as his own study at the Arizona State University SEM lab estimated its radius of 50 nm +/- 12.5 nm, i.e. width at about 100 nm or 0.1 micron.
See to yourself that Verhoeven's numbers is an unfortunate mistake by checking the Gillette patent, and posts by
Todd of the scienceofsharp.wordpress.com also known as ToddS on bladeforums.com and fuzzychops on straightrazorplace.com
https://www.google.com/patents/WO2010132645A1?dq=EP2429777+A1&ei=lhTYVITCD4rLsASK9IEY&cl=en (https://www.google.com/patents/WO2010132645A1?dq=EP2429777+A1&ei=lhTYVITCD4rLsASK9IEY&cl=en)
http://straightrazorplace.com/honing/96867-why-do-we-still-use-clean-leather-strop-5.html (http://straightrazorplace.com/honing/96867-why-do-we-still-use-clean-leather-strop-5.html)
https://bladeforums.com/threads/how-low-is-it-practical-to-go-in-microns-for-stropping.1259402/page-2 (https://bladeforums.com/threads/how-low-is-it-practical-to-go-in-microns-for-stropping.1259402/page-2)
In line with the above direct measurements are measurements of edge sharpness done with a PT50A instrument at
https://www.refinedshave.com (https://www.refinedshave.com) showing no difference between Gillette and Wilkinson razors. Thoroughness of his measurements is worthy of respect.
This, of course, in no way diminishes the importance of prof. Verhoeven's study on grinding with Tormek.
I even assume professors do not take measurements themselves - they evaluate them, at least in Jan's country this is a rule.
@Dutchman & Jan - the last bit is a humor :)
I would still be interested in a few more things about the CBN wheel, for example:
- Would you feel comfortable making a "spine side" repair, or other grinding where you reshape the blade profile? (ie, grinding 90 deg. on the wheel?)
- Would one CBN wheel provide the same results as the stock wheel's ability to work at both a coarse and fine setting?
- Any significant difference in grinding speed, one way or the other?
- and of course, longevity vs. a stock wheel, (which you probably can't answer now)
CB,
I don't know why spine side repairs could not be done the a CBN wheel on a Tormek. I do this work with a belt grinder, however, if I did not happen to have a belt grinder, I would feel comfortable using the Tormek with a CBN wheel. I would approach this slowly at first using a very light touch, probably using the platform to support the knife.
Incidentally, I have used the T2 with the DWF-200 600 grit diamond wheel to grind down a bolster. It did the job quite nicely freehand.
Unlike the Tormek SG wheels, CBN wheels are single grit only. For some applications, CBN wheels are a very useful second wheel. For general work, my go to wheel remains the SG. CBN works very nicely for things like reshaping turning tools. I have not tried it, however, I have become convinced that CBN is the ideal wheel for sharpening planer blades, at least for initial sharpening removing nicks.
I notice the difference in grinding speed during prolonged grinding. CBN does not need to be refreshed. It is designed to work with harder steels, although it also works woth hardened carbon steel. Initially, the grinding speed seems comparable with the Tormek wheels.
How long does CBN last? My best guess is a long time, depending on use. I would guess that the majority of forum members are still using their original SG grinding wheels. Some are on their second wheels. I do not see economy in CBN wheels for most users. Serious turners should have a CBN wheel. I would recommend one for anyone doing serious planer blade sharpening. For most of us, I would keep the SG nearby.
Ken
Quote from: Ken S on October 22, 2017, 05:29:03 PM
CB,
I don't know why spine side repairs could not be done the a CBN wheel on a Tormek. I do this work with a belt grinder, however, if I did not happen to have a belt grinder, I would feel comfortable using the Tormek with a CBN wheel. I would approach this slowly at first using a very light touch, probably using the platform to support the knife.
Incidentally, I have used the T2 with the DWF-200 600 grit diamond wheel to grind down a bolster. It did the job quite nicely freehand.
Unlike the Tormek SG wheels, CBN wheels are single grit only. For some applications, CBN wheels are a very useful second wheel. For general work, my go to wheel remains the SG. CBN works very nicely for things like reshaping turning tools. I have not tried it, however, I have become convinced that CBN is the ideal wheel for sharpening planer blades, at least for initial sharpening removing nicks.
I notice the difference in grinding speed during prolonged grinding. CBN does not need to be refreshed. It is designed to work with harder steels, although it also works woth hardened carbon steel. Initially, the grinding speed seems comparable with the Tormek wheels.
How long does CBN last? My best guess is a long time, depending on use. I would guess that the majority of forum members are still using their original SG grinding wheels. Some are on their second wheels. I do not see economy in CBN wheels for most users. Serious turners should have a CBN wheel. I would recommend one for anyone doing serious planer blade sharpening. For most of us, I would keep the SG nearby.
Ken
In part, the ability (or willingness) to do 90 deg. grinds might depend on the durability of the wheel itself... why I asked.
Having used the 600g diamond stone, my question would be, how much bolster work did you actually do? (and how long did it take?)
I know the CBN wheels are single grit.... the seller indicates it's a cheaper alternative to the standard stone... but not if you have to buy 2 to replace it.
Again, actual use will dictate longevity.
Right now, the main advantage I see to CBN or even diamond wheels, is the fact that they don't change size... allowing for some easy setup procedures to be implemented. Most of the ones now, have to be adjusted for wheel size.
Similar to Ken, I use a belt linisher for the "spine grind" in a broken tip repair, or for reducing a bolster.
Quote from: cbwx34 on October 22, 2017, 07:05:36 PM
Right now, the main advantage I see to CBN or even diamond wheels, is the fact that they don't change size... allowing for some easy setup procedures to be implemented. Most of the ones now, have to be adjusted for wheel size.
True, unless in bulk sharpening, where another advantage of not having to true the wheel after every a dozen of knives comes into play.
Quote from: wootz on October 22, 2017, 10:20:11 PM
Similar to Ken, I use a belt linisher for the "spine grind" in a broken tip repair, or for reducing a bolster.
I'm curious if you think this particular CBN wheel is capable?
Any comment on the other questions?
Quote from: wootz on October 22, 2017, 10:20:11 PM
True, unless in bulk sharpening, where another advantage of not having to true the wheel after every a dozen of knives comes into play.
True about truing, :) (although I find no such need after only a dozen knives).