Final report, CBN grinding wheels

[wootz]

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 - 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

[Dutchman]

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.

[Ken S]

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 As I have not shaved for twenty five years, my information may be outdated.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

[wootz]

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
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

In line with the above direct measurements are measurements of edge sharpness done with a PT50A instrument at
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

[cbwx34]

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)

[Ken S]

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

[cbwx34]

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.

[wootz]

Similar to Ken, I use a belt linisher for the "spine grind" in a broken tip repair, or for reducing a bolster.

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.

[cbwx34]

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?

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).