Edge Retention/Rolling Test Stand

[KnifeGrinders]

I am afraid for a rolled edge testing, the above repeatability target is unattainable just because the rolled edge scores within +/-50 BESS by its nature. It is sort of too springy.
In the meat factory we had to take 4 measurements in the same spot on each knife and average them because of that. Below are some example scores taken in the same spot (that was right under the V letter in the Victorinox etching on the blade) after 2 hours of cutting:

140
245
140
170

280
390
295
380

155
165
245
210

240
385
365
365

235
260
320
220

If we see that much dispersion in every single knife, no wonder in your case you see the dispersion among several knives.
I might be wrong, but I see value in two numbers: the amount of force needed to cause rolling, and then to cause inrepairable rolling.

[EOU]

You could be right KG. Near perfect edges can be measured near perfectly but damaged edges are presenting a problem. We are having problems inducing roll to the edge in an even fashion.  We'd like to produce a test that will answer many questions as opposed to just a few if possible. We're still working on it though and haven't run out of ideas just yet.  

Your input and interest is much appreciated KG.

[EOU]

This post is dedicated to Grepper and we'll explain why in just a little bit. We're continuing to improve on our methods and apparatus in creating a homogenous roll. Our latest data set taken after the edge was rolled was better than we could have hoped for. We're going to have to repeat the test to see if we can duplicate our first results. We've taken to calling our efforts an "engineered roll" so please get used to our using that term. 

We've developed a whole new way of rolling the edge in a repeatable and homogenous fashion hence our "engineered roll" terminology. We've need to tighten up our process so we will be refining our test fixture over the next couple of days. Then, hopefully, we'll post some sample results.

So on to Grepper. Mr. Grepper has taught us, repeatedly, in his posts about the importance of lighting when taking microscopic pictures. We thought that we would give you an example of what can be learned about edges if we all listen to Grepper's advice. Here's our initial picture of the edge that we just rolled:

   

It looks like something but what? We know that the edge is rolled because we can measure it. What does the roll look like?Here's what a little change in lighting can do. In this case we've simply altered the angle of the camera, thereby altering the angle that the light strikes the edge.

   

And here's another at just a slightly different angle:

   

Now we can see what we are dealing with and it looks just exactly as we imagined it should. The edge apex appears to be rolled at about a 30 or 40 degree angle. Thank you Grepper!

[Mark Reich]

Are you now rolling the whole edge instead of just a single spot?

If so, I'm excited, because that is what I was hoping for!

[EOU]

Hello Mark. We could roll most of or the entire edge with our new method but are not at this time. We're rolling about an inch of the edge now and measuring at and close to the center point of the roll.  While our initial results with this new process were the best we've seen to date we are in the midst of tightening up our test apparatus even further at this time. This means that we are building new parts for the test fixture. With any luck we'll be testing again tomorrow. We have high hopes at this time. Thanks for following along and for your comments Mark.

[KnifeGrinders]

There are jobs out there waiting for this edge-rolling tester.
Just yesterday read a post at the bladeforums.com about a dodgy high-end knife:
"...you can try and test it for edge retention if you think there is a problem with the steel... then if you find issues do a warranty request."

On the shoulders of the BESS edge sharpness testers, its way to recognition is expected to come way shorter.
Dare I say it is promising to be a counterfeit detector, and Australia might be the first offering this service to knife collectors.
At present, a suspected counterfeit must be physically posted to the manufacturer, with the expenses on the sender of course - we may provide a preliminary advice by this tester.

Will it be too daring to say that demand for this tester is going to be proportionate to the extent of counterfeits?

[EOU]

No surprise that you have your visionary hat on KG. We're getting used to that with you. You're correct, if this pans out we'll have a handle on a lot of things. For instance, and assuming that harder steels turn out to be less susceptible (significantly so) to rolling than softer steels, one could very quickly pick out an inferior counterfeit compared to the real McCoy (do you have "real Mccoys" in Australia?). Or, in the case of manufacturing defect, a poorly made or misrepresented knife could be identified as well. 

We have aspirations for the economic benefit to the commercial/industrial world as well. This test may well shorten the learning curve considerably. Dull edges aren't just an inconvenience to those guys. Dull edges cost them money. Anything that results in better, longer lasting edges for their processes will put a smile on their face.

We should be getting the "tightened up" version of the test stand out of manufacturing and into our hands this afternoon. If we have the same or better luck as we did with the prototype we'll be one step closer to success. 

Like we told Mark R., thank you for your comments and thanks for participating.

[EOU]

Tomorrow is going to be a test day here at EOU. The new parts are finished and incorporated into the assembly and our test knife has been newly sharpened and marked. With luck, more to report tomorrow.

   

[EOU]

Well its tomorrow now and we conducted a number of tests. As you can see from the picture below we've had to get a little more sophisticated with the test fixture design. We're not showing the actual impactor used in the tests because we're not quite at that point yet from an intellectual property standpoint.

   

We are able now to roll and measure edges, in a repeatable fashion, at multiple points on an edge. In addition, we are able to add or subtract weight from the process and measure a commensurate result in roll. Our standard roll rate is in the area of 275 - 325 points and you might be surprised to learn that this is accomplished with only a total piston weight of 100 grams. With our current system, a 300 point roll may not only be measured but seen and felt as well. 

It is obvious to us that this is going to be a big picture device as opposed to our edge sharpness testers that can detect very small differences. We think that this is a big picture project though. We're exploring here for things that make a significant difference as opposed to a small difference. We were just discussing the general philosophy of this a few minutes ago here in the office. We think that we should be able to expect a big increase in performance between a $50.00 knife and a $150.00 knife. At least three fold we'd hope. The same is true for sharpening methods and processes. We might not  change our methods for a 10% increase but we might for a 50% increase.

Before we send the structural tester out to our field testers like KG and Mark R. we're going to conduct a few more tests just to get a better feel for the kind of results we can expect. We'll likely test thin blades versus thick and sharper versus duller beginning test points. We may also test something like 15 degree sharpening angles versus 22. The results of these tests will be reported here. We think that we will save for our field testers the comparison of HRC 55-57 and 60-62 or VG10 versus 440C. That's going to be an interesting one. We expect to see a difference but, how much difference?

Of course there are likely a hundred different tests that may be conducted with this device. This grind geometry versus another, different sharpening techniques and methods etc. and all in a effort to discover whether there might only be 10 cents difference between them or 10 dollars. 

We know that we have several of our industrial customers who are following this thread and to you we have listened and made provision in the test stand for fixturing of most of the various edges you measure. We will keep you apprised of our progress.

[Bud]

I'm ready for more. When is the next test?