Edge Retention/Rolling Test Stand

[Bud]

Thanks for the heads up Mr. Knifegrinders. I read the postings. They don't seem very happy over there about this guys report. I'm guessing they wouldn't like this thread any better.

[Mark Reich]

 There are a lot of opinions and guessing going on there.  All of the posters could benefit from a sharpness tester.  You know, sharpen the blade, test the sharpness, cut some cardboard and then test again.  I suspect that some of those guys who claim their edges don’t roll may well be surprised at the results.

With all due respect, I don't think I've heard of anyone here cutting stuff. Like... never. Beg though I have.

Cardboard is a very silly thing to cut. There's absolutely no consistency. "How thick?" "Did you cut with the corrugations, or across them?" I've never heard anyone make any distinctions. Just, "I cut some cardboard". Hmmm.... 

It's also a pain because there'e so much drag involved with pushing the entire height of the blade through a stiff medium. There could be some torque involved. I don't know. I've only cut cardboard that actually needed to be cut. Can't say it's ever rolled an edge without hitting a staple.

This is not to say I've only cut a little cardboard. I was in the building trades for a few decades. I just never thought it was good testing material.

I Have made 50-500 cuts of manila rope.... I'd guess over 200 times. Who knows, could be over 300. Edges don't roll for me. They actually get Dull. Every damn time.

[KnifeGrinders]

I believe we soon will need a separate forum section for the "Structural Edge Tester", for sure when the field testers results begin feeding in.

My primary interest at the moment are "super-steels", and in view of the above interesting thread on the BladeForums, my 1st study will be on high Vanadium blades.

[Mark Reich]

I have never been able to read Bladeforum's sharpening discussion. I banned myself very many years ago.

I read the whole thread very carefully. It not only reminded me why I banned myself, it reinforced the decision. 

I have 3 Benchmade 710s in M390, because 710s are my favorite inexpensive folders, and M390 is the best steel available. It's modern and expensive, and that's exactly how it performs. 

Obviously, any edge can role, but in my experience M390 is not prone to rolling, it's the opposite- chippy. Even Benchmade's.

This is the first one I acquired. I reprofiled it to about 9°/side and polished it (EdgePro), just to prove that it was possible, which was insane, especially with the recurve. It was an accomplishment I won't repeat. 

Although it did measure BESS 14 on the KN100 with plastic nuts...

Mr. KG, I will be absolutely delighted to read your pronouncements regarding the "super steels".    

[subwoofer]

I have never been able to read Bladeforum's sharpening discussion. I banned myself very many years ago.

I read the whole thread very carefully. It not only reminded me why I banned myself, it reinforced the decision. 

I have 3 Benchmade 710s in M390, because 710s are my favorite inexpensive folders, and M390 is the best steel available. It's modern and expensive, and that's exactly how it performs. 

Obviously, any edge can role, but in my experience M390 is not prone to rolling, it's the opposite- chippy. Even Benchmade's.

This is the first one I acquired. I reprofiled it to about 9°/side and polished it (EdgePro), just to prove that it was possible, which was insane, especially with the recurve. It was an accomplishment I won't repeat. 

Although it did measure BESS 14 on the KN100 with plastic nuts...

LOL, forums are funny places, and I know many people who have had enough of certain forums, even to the extent of setting up their own....

If you are going to be 'controversial' you need to be as objective as possible and present the evidence. The edge tester is exactly one of those things where all you can do is say here are the results of my 'experiment' it seems to show this...

That is some lovely work on your re-profiling - how about putting that through the edge tester :-P

How is it that simple edges are so complicated? Perhaps this edge tester is going to need a standard 40 degree inclusive angle to allow us to compare, but then again it will be interesting to know how a blade steel preforms at 40 degrees, 35 degrees, 30 degrees, and other angles too.

Is there any chance it would even work for angles as large as scissor blades at around 78 degrees - would this even be of use as these blades are shearing? The extreme angle example is more to see if much larger inclusive angles on various tools would behave in a predictable way.

If the edge is diamond, ceramic or stone sharpened, has it been honed, and with what, will this affect the properties of the steel apex? For real working edges, the edge can be too sharp (thin); can we identify an ideal sharpness for the most stable edge for a given steel and edge angle? - I think we'll be at this for a while.

[Mark Reich]

Heh Heh! Thank you, Mr. Subwoofer, but as you guessed, this one will not be visiting the SET. 

After that much work, which literally took days, I immediately bought a duplicate. The first one is a testament to the madness of sharpaholics, and it was a difficult decision to even risk measuring it. BESSaholism won out.

I'm sure the SET will work for scissors, although I'm not sure of the benefit. 

I know for sure that every edge I test will be precisely sharpened on the EdgePro. Honestly, I believe it's been collecting dust since the M390 experiment took the joy out of using it.   

The EP is capable of extreme accuracy. Those magical little angle cubes are actually capable of 0.1° precision, and they are easy enough to use at that level on the EP. 

I'm not sure why the testing edges will need to be honed. I'm not sure what you mean. In fact, one of the biggest questions to be answered will be what role grit will have on edge stability, IMHO.

I've always said the EP is more of a scientific instrument than just a guided sharpener. Coupled with a KN100, we are going to find out the defining characteristics of the SET, and the steel of choice. There will be no more  guesstimation involved.

It's pretty darn cool to be in on the ground floor of revolutionary metallurgical science!

[Mike Brubacher]

Great posts Mark but you're showing your age with this little nugget that I extracted "Although it did measure BESS 14 on the KN100 with plastic nuts..." . "Plastic nuts?" That made me smile Mark. The original KN100's included two styles of clamping nuts, brass and plastic. Brass was standard and when used provided a standard piston weight of 55 grams. A naked piston weight of 55 grams would typically cause the test media to sever without any additional added weight when measuring standard DE razor blades. Replacing the brass nuts with plastic ones reduced the piston weight by some seven or eight grams. Usually, the test media would just sit on the DE edge when plastic nuts were used. Just goes to show how long and good a friend of edge testing Mark Reich has been and if I haven't said it before, I'm saying it now Mark, thank you!

[Blade Banter]

This would be a good test if the baseline could be set.  The media which is used to roll or dull the edge would need to be somewhat controlled to give the same pressure over at least 3 test weights.
   What would make it relatable would be corolated to something like rope cutting.  So if a certain dullness was obtained by making 50 cuts of rope the test would have a given weight applied which simulated the same wear.  
    I'm not sure how to how this works because there are so many different knife steels.

[EOU]

Good thoughts Blade Banter and welcome to the Exchange! We do hope to establish benchmarks with this device just as we have with our line of edge sharpness testers. How those benchmarks will be established has yet to be decided. We are a fair amount of general testing away from even establishing the parameters. The good news is that we are all back on duty now and our new SET parts are back from the powder coater. That means that we can begin putting SETs together and getting them out to our member testers. 

As an introduction, Blade Banter has just begun a YouTube channel that is dedicated to examining the various attributes, we believe, of folding knives. Here's the link https://m.youtube.com/channel/UC1v4yovZeJ1rwE8cuphPxgw

[Mark Reich]

Hello Blade Banter, Welcome to the Forum!

There are many things to learn from the Structural Edge Tester, and the difference between wear and rolling is certainly a prime example. 

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Thank You Mike, and you are welcome for sure. I have always felt very fortunate to have met you "in the beginning" as well. Thanks to the Godfather.  

Shoot. I thought the difference between the plastic and brass nuts was more significant than that.

What I remember most vividly is the shock of the media severing between the time I put the little plastic cup on the ram, and just as I was about to some lead shot. It definitely startled me!

After determining the Moritaka petty was within single digits with brass nuts, I switched to plastic, and went to work on the M390 with the EP.

For some reason I thought the brass nuts weighed more than that. I had "Plastic 14" written on the M390 with red Sharpie for some time, but here's one thing I don't remember- Are there more plastic parts to swap from the razor machine? I gave the razor machine away.

Time flies, as does my memory...