No man is prophet in his own country?

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Originally Posted by BobL

I'm not concerned with the same level of sharpness like some other folks on these forums but if I was to invest in one these, the sort of data I would find useful is;

1) What is the single point reproducibility of the system at varying degrees of sharpness? Eg std deviations of repeat tests on the same point on a blade at various sharpness levels?
2) how many points along a blade are needed to adequately test sharpness. I can't imagine one or two points especially on longer blades being sufficient?
3) How many times during a sharpening process is testing recommended?
4) Is it possible once you have a successful sharpening protocol to not test at all, and still achieve optimum sharpness?

[EDIT] I had a quick look at some of the vids - worth a look if you are into that level of sharpening.

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This sharpness tester is spot sampling.
Though a BESS calibrated edge sharpness tester is a great tool to determine the degree of sharpness, by itself it is not sufficient to verify quality of the whole edge as it samples only one point on the edge, even when you take a couple of measurements at its different portions.

Measuring sharpness at the same spot of the edge is all needed for guiding your sharpening session in the right direction.

The professional edge sharpness tester PT50B has 5 BESS of resolution (+/- 0.05 micron edge apex width).
The industrial edge sharpness tester PT50A has 1 BESS of resolution (+/- 0.01 micron edge apex width).

5 BESS of resolution is more than adequate for all the sharpening discoveries and perfecting your sharpening process.
(But for knives in my own collection I use the PT50A :rolleyes: )

"3) How many times during a sharpening process is testing recommended?"

We are talking here about refining a deburred edge, obviously.
Before I got my first PT50, I used to overhone & overstrop the edge past that sweet point of the maximum sharpness.

When I am sharpening in a "study mode", trying a new abrasive or working on changes to the sharpening routine, I may test as often as after every 1-2 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 para-micron and submicron range, after every 1-2 passes.
It depends not only on the abrasive grain size, but also whether it is a paper wheel, a rock-hard felt wheel, a leather wheel, or a strop - we have sets of them with various grits abrasives.

"4) Is it possible once you have a successful sharpening protocol to not test at all, and still achieve optimum sharpness?"
Yes.
After a sharpening protocol has been established and proved, I pass it to my team to follow, and we measure sharpness just twice - before and after sharpening.
We have a BESS Universal licensee obligation to give customers true and accurate sharpness scores

http://knifegrinders.com.au/Home/BESSslip.png

Another useful and potentially lucrative document to produce would be a compendium of your various sharpening protocols along with your instrumental data.

How do the various sharpness measurement results correlate with real world utility? For instance, a very sharp knife blade for a machine may be useless in practice if it isn't used to cut material with physical properties similar to the test material used with the instrument.

How does the measured sharpness vary with grind angle, all else held constant?

Can the instrument reliably and repeatably assess edge retention?

Can you help me make a decision with a task we see daily?

Suppose you have set edge on 2 blades, and going to deburr and hone them:
one scores 160 BESS, i.e. has about 1.5 micron edge apex, scraping shaving your forearm;
the other scores 110 BESS i.e. has near 1 micron edge, smooth shaves with, but not against the hair grain.

Suppose you have the same grit honing compound on the wheels we use:
a Tormek leather wheel, a paper wheel, and a flint-hard felt wheel.
On which wheel will you hone which blade?

Tell me your best answer, and I will tell you what our protocol is based on the the sharpness tester readings.

I don't work with razors, nor do I sharpen them. I polish carving chisels using the Tormek leather profile wheel. I have heard it suggested that knives are best polished on hard paper wheels. I've never heard of flint hard felt.

Well, I knew the same little in the beginning.
These may well be chisels or knives, doesn't matter.
Suppose number one is not shaving at all, just scraping - but you aim to get the both blades razor sharp.
Don't want to take a guess, from your experience and what you know about sharpening?
Anyone?

Your challenge raises a number of points that have been discussed at great length on this forum in various threads.

At this point, nobody has offered an answer for a whole variety of questions about the concepts of sharpness in a quantitative way including:

1) How sharp is sharp enough?

2) Is optimal sharpness for one use optimal for other uses?

3) How is sharpness measured?

4) What is the trade off between sharpness and durability for any particular application?

5) How is optimal sharpness attained?

6) How do the physical properties of the material constituting the sharpened tool influence real world performance?

Unfortunately no one has offered anything other than a miasma of personal experience and opinion in answer to any of these questions.

Can you show us how the instrument on offer is really anything more than a way of testing how good edges are at cutting fishing line?

Half of your questions have been put too broad to answer, and some confuse sharpness and cutting performance.
There is no trade off between sharpness and durability for any application, you might have meant the edge angle - any can be made equally sharp.
Blade geometry, angle and profile (other than radius at the very edge apex) have no bearing on BESS scores as such.

My "challenge" can be solved with common sense and everyday sharpening experience everyone on this forum surely has.

As to yours "Can you show us how the instrument on offer is really anything more than a way of testing how good edges are at cutting fishing line?" - this is exactly what this thread is all about.
Please keep posting

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Originally Posted by KnifeGrinders

Half of your questions have been put too broad to answer.

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Okay, so as to the other half?

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Originally Posted by KnifeGrinders

There is no trade off between sharpness and durability for any application, you might have meant the edge angle - any can be made equally sharp.

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Interesting assertion.

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Originally Posted by KnifeGrinders

My "challenge" can be solved with common sense and everyday sharpening experience everyone on this forum surely has.

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If the answer is truly common sense why the insult? "Well, I knew the same little in the beginning."

No insult was meant, mate - I meant your words on not knowing paper and felt wheels - I knew the same little about them in the beginning.

When I shaped my sharpening hobby into a business, I had to move from benchstones and strops to powered wheels, and from guessing to quality control tools like the BESS sharpness tester, microscope and others.

Yet that task we are talking now about can be solved with common sense, but the solution can be proved with instruments only.
And a sharpness tester helps to better sharpening, for yourself or businesses.

Honestly, this thread is not as much about selling the instrument - here I share my experience with the instrument I found useful.
I have limited experience with sharpening your tools, but thought you guys might benefit as well, as hundreds of woodworkers who already use this sharpness tester can't be wrong.

The woodworking community typically uses diamond plates, stones of various kinds +/- strops and or devices like the Tormek. As I mentioned, I'm not interested in knives or razors though there are some users here who are. My feeling is that they are more likely to be familiar with the paper and felt wheels. If these wheels are truly useful for woodworking tool sharpening tell us how and show us some examples.

You're selling the product and I want to know more. Unfortunately you've not answered my interest.

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Originally Posted by KnifeGrinders

No insult was meant, mate - I meant your words on not knowing paper and felt wheels - I knew the same little about them in the beginning.

When I shaped my sharpening hobby into a business, I had to move from benchstones and strops to powered wheels, and from guessing to quality control tools like the BESS sharpness tester, microscope and others.

Yet that task we are talking now about can be solved with common sense, but the solution can be proved with instruments only.
And a sharpness tester helps to better sharpening, for yourself or businesses.

Honestly, this thread is not as much about selling the instrument - here I share my experience with the tool I found useful.

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I'm all for instrumental analysis.

This is a screenshot of the data page of a study I've been doing of the hardness of saw blades. This is about 1/8th of the full page (62 X 626). Unfortunately it's so big now (1.38MB) that I can't practically post it in its entirety. Nonetheless I have posted the results of my work.


Attachment 422010


Show us some of your data.

I recognise your doubts, and remember mine before I bought the tester for myself.
Australians are in a better position, thanks to a hire option we offer - no such thing in the US.
You can hire the BESS sharpness tester from us for a cost of a pack of Marlboro, play with it for a month, and either return or keep...

At first I didn't so much doubt but truly wanted to know more about the instrument. Now, in the face of your resistance to producing data, I doubt.

Interesting discussion but shouldn’t the first post have been placed in the Market place as it was obviously a sales pitch?. Even the sold to “James in Newcastle” fits that bill.
I have no problems with discussions on sharpening techniques but please Knifegrinder, stop the sales pitch or put it in the appropriate area.

Lappa, the little margin I have from selling these instrumets isn't even worth the label "marketing" - some beer money, maybe.
I started using this sharpness tester the next year it was invented, when no one knew much about it, and quickly became the BESS convert. Nowadays it is used all over the places, but Australia - I do recommend it, whatever my recommendation is worth.
Basically, I've said all I wanted and don't mind this thread to be locked or moved or what is appropriate.
Heading for my workshop now...