FYI, we've added a sharpness chart to the Sharpening Resources section of our website Sharpness Chart >> (http://knifegrinders.com.au/Manuals/Sharpness_Chart.pdf)
Includes data for all traditional sharpness tests.
Great chart.
How sharp is it that it can slice a phonebook paper? (Not push cut)
Same as slicing a sales docket/receipt – 300 BESS or about 0.5 micron edge
Quote from: wootz on November 25, 2017, 05:52:29 AM
FYI, we've added a sharpness chart to the Sharpening Resources section of our website knifeGrinders.com.au (http://knifegrinders.com.au/12Resources.htm)
Includes data for all traditional sharpness tests.
Good stuff... printed out for reference. Thanks!
Quote from: sharpco on November 25, 2017, 12:35:14 PM
Great chart.
How sharp is it that it can slice a phonebook paper? (Not push cut)
There's a bit more to cutting phonebook paper... most has a "grain" to it, and cutting it with the grain, is a lot easier than across it. (Not sure how that translates in BESS scores though).
Good work, Wootz.
Ken
Practical use of these sharpness tests is not as much to determine the already attained sharpness, as to guide your sharpening process.
Some tests are more useful than others as they tell you when you have to change to a finer grit.
Certain sharpness tests are so precise that can tell which grit number to choose.
I don't shave forearm or do hanging hair tests anymore, as the BESS score itself tells me everything.
Measuring the edge sharpness with the PT50 tester at the same spot on the edge guides my sharpening session in the right direction.
For example, how we use this BESS edge sharpness tester in honing.
We keep honing while the sharpness score keeps improving (i.e. lowering), and stop when the reading has stopped changing.
At this point, should you continue honing - you will lose the edge sharpness you've just achieved.
At this point the right thing to do is to change to a finer hone.
The BESS edge sharpness tester indicates those breaking points in the sharpening sequence, where you have to change to a finer grit, and not to ruin the edge by overhoning.
You know you are overhoning the edge when the BESS reading increases.
When I see this, not only I change to a finer grit, but may also take a shallower honing angle.
I compiled this Sharpness Chart for those who haven't got the sharpness tester yet.
The apex width values given in the chart for the "Traditional tests" is the earliest attained sharpness (from the dullness end of the range) when the test can be performed more or less cleanly.
Note though that the BESS score tells the edge apex width only to a first approximation for these "traditional tests".
You can pick tests from this chart, and build your own system of indicators telling you when you have to change to a finer grit in refining your edge.
BTW I never took seriously that single ply toilet paper test, and will replace it with a cigarette paper test, as it is a way more standard test media.
Quote from: wootz on November 28, 2017, 12:44:10 PM
For example, how we use this BESS edge sharpness tester in honing.
We keep honing while the sharpness score keeps improving (i.e. lowering), and stop when the reading has stopped changing.
At this point, should you continue honing - you will lose the edge sharpness you've just achieved.
At this point the right thing to do is to change to a finer hone.
The BESS edge sharpness tester indicates those breaking points in the sharpening sequence, where you have to change to a finer grit, and not to ruin the edge by overhoning.
You know you are overhoning the edge when the BESS reading increases.
When I see this, not only I change to a finer grit, but may also take a shallower honing angle.
So, just to satisfy my curiosity... are you testing every knife you sharpen? I can't imagine what you described being used on every knife... although that's what it sounds like.
Yes for each type of steel new to us, when we have to develop a sharpening protocol for it.
When I am sharpening in a "study mode", I may test as often as after every 2 passes to catch the tendency and breaking points.
Usually on abrasives down to 3 micron grain I test after every 2-3 passes.
Further in the submicron range, after every 1-2 passes.
When I am finished, the floor next to my sharpness tester looks like hairdresser's covered with cuts of the test media line.
After a sharpening protocol has been established and proved, I pass it to our team to follow, and we measure sharpness just twice - before and after sharpening.
Quote from: wootz on November 28, 2017, 08:22:00 PM
Yes for each type of steel new to us, when we have to develop a sharpening protocol for it.
When I am sharpening in a "study mode", I may test as often as after every 2 passes to catch the tendency and breaking points.
Usually on abrasives down to 3 micron grain I test after every 2-3 passes.
Further in the submicron range, after every 1-2 passes.
When I am finished, the floor next to my sharpness tester looks like hairdresser's covered with cuts of the test media line.
After a sharpening protocol has been established and proved, I pass it to our team to follow, and we measure sharpness just twice - before and after sharpening.
Where is THAT chart.... ;)
Cigarette paper test - slice the edge furthest from fingers holding the cigarette paper, then push-cut down.
Becomes possible at 30 BESS or 0.06 micron edge, but cleanly performs only at 20-25 BESS or 0.05 micron edge.
This one is a highly precise test due to standardized "test media", and I replaced with it the toilet paper test in the sharpness chart on our website http://knifegrinders.com.au/Manuals/Sharpness_Chart.pdf (http://knifegrinders.com.au/Manuals/Sharpness_Chart.pdf)
I never took that single ply toilet paper or facial tissue tests seriously anyway.
Quote from: cbwx34 on November 28, 2017, 09:30:43 PM
Quote from: wootz on November 28, 2017, 08:22:00 PM
Yes for each type of steel new to us, when we have to develop a sharpening protocol for it.
When I am sharpening in a "study mode", I may test as often as after every 2 passes to catch the tendency and breaking points.
Usually on abrasives down to 3 micron grain I test after every 2-3 passes.
Further in the submicron range, after every 1-2 passes.
When I am finished, the floor next to my sharpness tester looks like hairdresser's covered with cuts of the test media line.
After a sharpening protocol has been established and proved, I pass it to our team to follow, and we measure sharpness just twice - before and after sharpening.
Where is THAT chart.... ;)
Appreciate your sense of humor, mate.
Our protocols may get into the public domain only over my dead body.
Curtis, you can read about our best sharpening protocol in this thread on the BESS forum:
http://www.bessex.com/forum/showthread.php?tid=209&pid=1602#pid1602 (http://www.bessex.com/forum/showthread.php?tid=209&pid=1602#pid1602)
In the Internet age, it is easy to forget that some things are not free. In Wootz' case, the time and expense he has put into developing his protocols are part of his livelihood. He has every right to protect them.
I have run into the same situation with Steve Bottorff's Sharpening School DVD. Steve asked me to review it for the forum. He also generously shared parts of it, more than a teaser trailer. From time to time, questions arise on the forum which are answered in Steve's DVD. I often email Steve, and he usually posts an answer. I do not answer those questions; I consider the information on Steve's DVD his intellectual property. Likewise, I consider Wootz' protocols his intellectual property.
Some of us, myself included, make our ideas open source. In my case, I am retired and have never been a professional sharpener. I have freely used and credited ideas posted by other members. I have tried to add to the general knowledge base with no thought of financial gain. This is in no way a criticism of those of us who are professional sharpeners with specially developed techniques. I am sure I would feel differently if my income depended upon a distinct business I had built. Let us not forget how much expertise the professional sharpeners on this forum have shared.
Ken
Quote from: wootz on December 02, 2017, 01:39:44 AM
Curtis, you can read about our best sharpening protocol in this thread on the BESS forum:
http://www.bessex.com/forum/showthread.php?tid=209&pid=1602#pid1602 (http://www.bessex.com/forum/showthread.php?tid=209&pid=1602#pid1602)
Interesting read....
Next step... some "edge retention" testing? ;)
Now reading through articles at http://www.cliffstamp.com/knives/ (http://www.cliffstamp.com/knives/) - heaps there about edge retention.
Those questions SHARPCO asks about microbevel and edge retention are answered there.
An easy and immediate remedy for edge retention is to use the right cutting board
https://forum.tormek.com/index.php?topic=3452.0 (https://forum.tormek.com/index.php?topic=3452.0)
I've been thinking about this thread... and should modify my request... from "edge retention" testing to "burr/wire edge" testing. One thing I've learned over time, is that some sharpening methods can create a wire edge that, as opposed to a burr, tests very sharp, but is very hard to detect. Usually, however this wire edge won't hold up to much cutting.
One quick/easy way to test, is to make a slice thru a thin piece of paper (I use phonebook paper), then make a couple of cuts thru cardboard, maybe throw in a couple of cuts thru copy paper, or a single rope cut, then back to the phonebook paper. To pass, the knife must make another clean slice.
You're not testing for "absolute sharpness"... in other words, it doesn't matter if the knife could push cut the paper, or pass a "higher level" test... but being able to make a clean slice thru phonebook paper before and after, has become a fast way to check for a wire edge.
Maybe give it a try?
The KN100 Operating Manual in the manufacturer library http://www.edgeonup.com/Library.html (http://www.edgeonup.com/Library.html) has speculations about the burr, and the wire burr in particular, accompanied by edge sharpness measurements.
Quote from: wootz on December 10, 2017, 09:25:07 AM
The KN100 Operating Manual in the manufacturer library http://www.edgeonup.com/Library.html (http://www.edgeonup.com/Library.html) has speculations about the burr, and the wire burr in particular, accompanied by edge sharpness measurements.
Trust but verify. ;)
I don't think the answer is to use the same machine you're getting your sharpness results from, to tell you whether or not there's another reason for it. (Especially when other options are available).
Wootz.
I have been told that the knife can be very sharp even though it has a very fine burr.
So I want to ask you.
How sharp is it that Burr is completely gone? In other words, what is the minimum level of sharpness that the burr can't exist?
These tests had been done by Mike Brubacher and described in that KN100 Operating Manual I referred to above, pages 39-42.
What you read there is in line with what Todd Simpson found out and illustrated by SEM images on his scienceofsharp.wordpress.com
A continuous wire burr is seen as a structural part of the apex, folding to one side of the edge soon after sharpening; "foil burr" is just another name for the wire burr.
When straightened by steeling or stropping, it is your sharpest edge.
Deburred completely by high-angle stropping, i.e. at an angle larger than the edge angle, the edge will be less sharp initially, but stay sharp for longer as no burr rolling occurs with the knife use (well, at least in soft food cutting on an edge-friendly cutting board).
In the KN100 Operating Manual, Mike Brubacher gives BESS scores for a knife edge in the 200-300 BESS range, and shows how the wire burr changes the score.
The BESS scores I get when I sharpen deliberately preserving the wire burr:
- immediately after sharpening 55-60;
- 2 houra later 80 - I attribute this worsening chiefly to oxidation, and to a lesser degree to the burr bending - the edge oxidation is known to worsen the score by 5-20 BESS;
- in 10 hours 115 BESS - due to the wire burr folding to one side.
By gently stropping this edge on a clean leather, after just 4 very light knife-weight alternating strokes, I get the sharpness score back to about 70-80 BESS - thanks to aligning the wire burr.
Mike B. says it takes 6-8 hours for the burr to spontaneously return to its rolled position due to the metal memory.
USB microscope image of the wire/foil burr
(http://knifegrinders.com.au/photos/wire_burr.jpg)
For comparison to the above, look at the same edge, but now completely deburred by fine honing on a paper wheel with a 0.5 micron abrasive at an angle +0.4 degree larger than the edge angle (e.g. honing a 15 dps edge at 15.4 degrees):
(http://knifegrinders.com.au/photos/wire_deburred.jpg)
The BESS scores I get for the deburred edge:
- immediately after sharpening 65;
- 2 hours later 70;
- in 10 hours 70 BESS;
- next day 72 BESS - no deterioration with time.
You see now why almost every our sharpening protocol has a final step of fine honing on a paper wheel at +0.4 degree.
I've checked with the US Sharpeners Report when our study on this is published, and was told they couldn't make it into the December issue, but will for sure in February.
BTW the December issue has a very interesting and detailed article about a sharpening and knife rental service in Las Vegas.
Interestingly, when Judy, the Sharpeners Report editor, sharpened her knives at a local shop in Minnesota they showed her the BESS score before and after her batch was processed - similarly to how we do it in Australia.
Amazing post! Your knife sharpening technique seems to have reached the apex.
It is no exaggeration to say that knife sharpening is the process of making burr and removing it.
BTW, Tormek says no need honing after using the SJ stone and I understood it means SJ can deburr completely. However, according to page 26 of the "Experiments on Knife Sharpening -John D.Verhoeven", it's not true. SJ produce very small burr, so we need the next step(maybe it's a final).