Problem Knife?

R

Robert Ptacel

Joined
Feb 1, 2007
Messages
314
Does anybody have that one knife that just won't respond to sharpening like your others? I have a BM Monochrome that just gets hair scraping sharp and has minute micro chips in the edge. The primary edge bevel is about 24 to 26 included and the secondary is 40 included. I assume the heat treat just can't take any thinner. I've stopped thinning and just maintained the 40 degree secondary and the edge is getting smoother. I have never had a knife this stubborn. It makes me wonder what is wrong with me but all my other knives are sharp. Ever had a knife like that?
 
If I remember correctly the monochrome is N690co steel, it should be able to handle a very thin angle and should get extermely sharp. Try using a strop to polish the edge and get rid of the burr that may be causing you problems.
 
Been there, done that. Only after resharpening at 40 included and getting back into the thicker part of the edge are the micro chips starting to disappear.There never was a burr because after sharpening and stropping I even checked it with a pin.
 
I have a 5 inch outdoors knife that wasn't completely ground completely at the factory... it's like the edge didn't meet in the middle and there was still a paper thin amount of stock there... So I had to reprofile it and lay the edge down a little bit and now it cuts like a razor. Usually any knife with edge problems can be fixed with a simple reprofile from what I've seen. I did use to have a Benchmade in ATS-34 that would not take an edge for the life of me. I did everything I could... it never cut well at all. Became a toolbox knife. I've never liked ATS-34 though. Every knife I've owned in that steel (About 5) had some kind of problem. That was the only one that wouldn't sharpen right but the rest chipped easy or got broken tips way to easy... it's like the steel has no flex to it at all or something.
 
This knife has been reprofiled several times and it seems that when I thin it the micro chips start. I sharpen it the same way I do every other knife.
 
Checking with a pin won't always let you know if ther is a burr, sometimes a burr will be present and not be able to be felt. In that case I would suggest looking at the edge under bright lighting to see if you can see the burr.

This knife is made from the same steel and has a 15 or less stright bevel on it. Its a great performer and have had no problems with micro chips.
Picture295.jpg
 
Robert Ptacel said:
Does anybody have that one knife that just won't respond to sharpening like your others?
Click to expand...

My CentoFante III....

I use the sharpmaker and im not liking the fine and med stones; i might get

the ultra fine and diamond replacements or just save up and get the Edgepro

Apex full kit.
 
What are you cutting that is causing these microchips?
 
Robert Ptacel said:
Does anybody have that one knife that just won't respond to sharpening like your others? I have a BM Monochrome that just gets hair scraping sharp and has minute micro chips in the edge. The primary edge bevel is about 24 to 26 included and the secondary is 40 included. I assume the heat treat just can't take any thinner. I've stopped thinning and just maintained the 40 degree secondary and the edge is getting smoother. I have never had a knife this stubborn. It makes me wonder what is wrong with me but all my other knives are sharp. Ever had a knife like that?
Click to expand...
Very similar results here with a Benchmade Monochrome: After taking the primary down to 12 deg/side I tried it with a 17 deg/side microbevel, but edge retention was not good. With a 20 deg/side microbevel, things improved, and in fact achieved very respectable sharpness. And FWIW this is typical of many high alloy stainlesses, even VG-10 for example performs much better with a 20 deg/side microbevel than at 17 deg/side.

Note also that under magnification, the Monochrome's N690 was found to have very fine microchipping after use -- much finer than any other steel I've examined that tends to microchip, rather than wear smoothly. Now this could be viewed as a positive or a negative, depending on what you're cutting and how you feel about such things. Personally I prefer steels like the Sandviks or nonstainless carbon steels that aren't prone to microchipping. YMMV.
 
If we were a little closer I'd say I could look at person but I'm south of detroit.
 
knifenut1013 said:
If we were a little closer I'd say I could look at person but I'm south of detroit.
Click to expand...

Thanks for the offer. It is getting smoother but only as the edge gets thicker. It is if the edge can't support a thinner edge but that is really not that thin. Never had that problem before so it is a stumper.
 
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