Sharpness Chart

[wootz]

FYI, we've added a sharpness chart to the Sharpening Resources section of our website Sharpness Chart >>
Includes data for all traditional sharpness tests.

[Sharpco]

Great chart.

How sharp is it that it can slice a phonebook paper? (Not push cut)

[wootz]

Same as slicing a sales docket/receipt – 300 BESS or about 0.5 micron edge

[cbwx34]

FYI, we've added a sharpness chart to the Sharpening Resources section of our website knifeGrinders.com.au
Includes data for all traditional sharpness tests.

Good stuff... printed out for reference.  Thanks!

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).

[Ken S]

Good work, Wootz.

Ken

[wootz]

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.

[cbwx34]

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. 

[wootz]

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.

[cbwx34]

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....

[wootz]

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
I never took that single ply toilet paper or facial tissue tests seriously anyway.

[wootz]

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.

[wootz]

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

[Ken S]

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

[cbwx34]

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

Interesting read....

Next step... some "edge retention" testing? 

[wootz]

Now reading through articles at http://www.cliffstamp.com/knives/ - heaps there about edge retention.

Those questions SHARPCO asks about microbevel and edge retention are answered there.