Edge Retention/Rolling Test Stand

[Mike Brubacher]

Well now you went and made me check my memory Mark. Two brass nuts weigh 8 grams, total. Two plastic nuts weigh 1 gram, total. For once, I got something right so I'm feeling pretty good right now.

[Mark Reich]

And looking good!

Yer just an all around good guy, Mike.

[EOU]

We're not just sitting on our thumbs here so a quick update. We will begin shipping out the new SET (Structural Edge Testers) units later this week. One of the units will be headed to Australia and another to the UK so we're trying to cover the corners as well as the middle. It is our plan, here at EOU, to begin generating a knowledge base that can be compared and referred to by our test community and customers. 

The first baseline will consist of samples constructed of A2 tool steel hardened in two point increments beginning at HRC50 through HRC62. We'll produce multiples at each hardness level so that we can test for other sharpening parameters such as sharpening angle, initial sharpness level etc. We'll also produce a set that includes a 30°  "chisel grind" for our woodworking and industrial customers.

We worked Mark Reich very hard over the telephone this morning and extracted as much advice from him as we could with regard to steels, heat treating and hardening processes. Thank you very much Mark for the guidance. This will be our first real effort inside a structured and comprehensive test group of samples. We hope then to expand the next round to something on the order of 440C and then, later yet, onto some of the more exotic knife steels. 

Of course the goal here is to discover what properties of sharpened steel edges contribute and which seem to mitigate edge rolling.  With luck, we'll have a much better handle on those questions soon. 

On another front we have finally broken down and purchased a new hardness tester. Should be here on Friday. While we're waiting for our test samples to be produced we'll backtrack and conduct hardness tests on some of the knives that we have previously tested and reported in this thread but were only able to give estimates of HRC hardness levels. We'll report those actual hardness levels here next week and perhaps, a few others that you might find interesting. Should be an interesting exercise as well as good practice.

[Bud]

This sounds like a well laid plan. Very interesting and will be anxious to hear the results.

[EOU]

Well, one Rockwell Hardness Tester. 

   

Glad it wasn't priced by the pound or we couldn't have afforded it.

[Rupert Lucius]

WOW!  4331 post to this thread - may be a record for this entire forum?

Rupert

[EOU]

Yes Rupert and 14 pages as well. We think that it is time to begin another thread that places much of what has gone before into a sort of "Cliff Notes" condensed version and then go forward from that point in the new thread. This seems like it might be good timing for just such a move since we have now begun shipping SET Units to outside testers. Here's what the primary parts look like and to the right, an assembled SET unit that is headed, Monday, to KG in Australia. 

                                                               

[KnifeGrinders]

Yes Rupert and 14 pages as well. We think that it is time to begin another thread that places much of what has gone before into a sort of "Cliff Notes" condensed version and then go forward from that point in the new thread. This seems like it might be good timing for just such a move since we have now begun shipping SET Units to outside testers. Here's what the primary parts look like and to the right, an assembled SET unit that is headed, Monday, to KG in Australia. 

                                                      

Much appreciated, can't wait for it at Knife Grinders.
I've been thinking of the SET testing plan these weeks,  and have several testing lines/directions in mind; high time to draft them in detail before the device arrives.

So proud Australians are among the first to reveal the unseen about the edge rolling.

We've needed something like SET to increase awareness of BESS and EOU in our hemisphere.
Though a BESS edge sharpness tester is an ultimate instrument to determine sharpness, sharpness (read edge apex width) is only one parameter the knife performance depends on, while used together with SET, this tandem should give us pretty comprehensive idea of the whole edge, not just its apex, what to expect of it and how it will perform.

[Rick Kr]

Greetings.  New member here, at least my first post here on the BESS forums.  I come via the Tormek forum and am a novice sharpener but a far more accomplished machinist.  

I like the notion of testing for edge rolling.  I think the proposed device/method is mostly a good idea.  I agree with KG about using a PT50 to measure the force. I was thinking of this in a different manner, one where the measurement of force occurred through the use of a device on the top of the ram, much like a hydraulic press.  I think the PT50 idea is better as it is already a known entity and a standard of comparison.  

I share a concern expressed by Mark Reich about how slicing should be part of the testing method.  I think this because it seems to me that it isn't just pressing downward that rolls the edge, but lateral movement along with pressing down.  I think his concern about pressing only at 90º is valid as well, as that also is not how knives get used and edges rolled.  

I think that a knife, per se, may not be the best test edge, but rather something known to much more standardized, such as a DE razor, utility knife blade or a single-edged razor with the reinforce backbone.  These could be tested for sharpness out of the box and rolled and tested again.  But I wonder if they shouldn't be dulled and then sharpened by some standard process and then tested.  I think they should not be tested in just a single location, but rather, drawn along the piece of steel to simulate actual use, measuring and keeping the force uniform, and probably at a slight angle so as to cause the edge to roll to one side.  Probably they should be tested both vertically with only downward force and also at an angle and then also with drawing along the steel strip.  I know that gets into a lot of testing, but I think these are all things that should be considered when deciding how to begin the testing. 

Thanks,

Rick Kr

[Rick Kr]

Greetings.  New member here, at least my first post here on the BESS forums.  I come via the Tormek forum and am a novice sharpener but a far more accomplished machinist.  

I like the notion of testing for edge rolling.  I think the proposed device/method is mostly a good idea.  I agree with KG about using a PT50 to measure the force. I was thinking of this in a different manner, one where the measurement of force occurred through the use of a device on the top of the ram, much like a hydraulic press.  I think the PT50 idea is better as it is already a known entity and a standard of comparison.  

I share a concern expressed by March Reich about how slicing should be part of the testing method.  I think this because it seems to me that it isn't just pressing downward that rolls the edge, but lateral movement along with pressing down.  I think his concern about pressing only at 90º is valid as well, as that also is not how knives get used and edges rolled.  

I think that a knife, per se, may not be the best test edge, but rather something known to much more standardized, such as a DE razor, utility knife blade or a single-edged razor with the reinforce backbone.  These could be tested for sharpness out of the box and rolled and tested again.  But I wonder if they shouldn't be dulled and then sharpened by some standard process and then tested.  I think they should not be tested in just a single location, but rather, drawn along the piece of steel to simulate actual use, measuring and keeping the force uniform, and probably at a slight angle so as to cause the edge to roll to one side.  Probably they should be tested both vertically with only downward force and also at an angle and then also with drawing along the steel strip.  I know that gets into a lot of testing, but I think these are all things that should be considered when deciding how to begin the testing. 

Thanks,

Rick Kr

Well, I see that I posted after having read only the first page or two, not realizing the most recent posts were at the end on page 14 (at this time). I'll have to go thru and read the rest. My comments may not have much relevance or contribute anything new, given the extensive discussion that I was unaware of. I'll do a better job of reading more be fore posting in the future.

Rick