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TOPIC: Sharpness Testing Jig

Sharpness Testing Jig 1 year 2 weeks ago #13422

  • Mikedoh
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Wow!
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Sharpness Testing Jig 1 year 2 weeks ago #13424

  • EamonMcGowan
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You are the man! B) My guy has not completed my rig yet? Wait till he hears about this? I think I'm going to have to let this update go? But it never hurts to ask? Lol :whistle:

My preliminary numbers are very close to yours. I think I'm on the right track? I have been testing my different steels and angles and the one that really stands out is Benchmade I got over the weekend at a thrift store. I don't know the steel type but I put a 15* 80-1000K diamond with a 14/10um strop finish on it and wow does it test well! I would have thought a 5/3.5 strop would be sharper? but not so?
The definition of insanity is to do the same thing over and over again and expect a different result?
An old Irish toast, May the wind always be at your back, may you always have work and may you be in heaven a half hour before the devil knows your dead. Cheers!
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Sharpness Testing Jig 1 year 1 week ago #13566

  • wickededge
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I've been doing some more fun stuff with the machine today. I'm setting up to do a side by side comparison of two blades, both taken to the 10k Chosera stones then stropped down to .125um CBN on kangaroo, one at the same sharpening angle of 15° and the other stropped at 13°. I won't spoil the results yet as to which is sharper more durable, that will have to wait until tomorrow. In the meantime, I can share how the edge of the one stropped at 13° fared over 40 repetitions of the test. The chart below shows the grams of force required to rupture the tape at each repetition:

hfe4b0e0.jpg


With each repetition I'm applying force to the exact same spot on the blade. There are some peaks and valleys within the overall upward trend of force required. The higher the number, the duller the blade is getting. I suspect the very edge is deforming under the load and occasionally it deforms to a shape that momentarily improves its sharpness and that is what we are seeing in the valleys. Other explanations for the valleys could be weak spots in the tape or imperfections in the collar holding the tape. If it is imperfections in the collar that we're seeing, we'll probably be able see corresponding valleys in subsequent series which would represent the locations on the collar that are different from the norm.
--Clay Allison
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Sharpness Testing Jig 1 year 1 week ago #13583

  • wickededge
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Here are two nice shots at 2000x of the edge of the blade stropped at 13°. One is of the section of blade that was being tested, the other is of a section just a millimeter down that didn't have any load:

hc93dd84.jpg

Edge Baseline - No Testing - 2000x

hdd5023b.jpg

Edge After Testing - 40 Repetitions - 2000x

The deformation is pretty easy to see.
--Clay Allison
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