unsharpenable knife?

[John Frankl]

Have you ever had this problem?

I am finishing up a nice little integral blade. But before I assemble the knife, I want to give the blade a thorough testing.

Well, I have tried to put an edge on it with everything from diamond stones to arkansas stones, norton indias to japanese waters. To my eye and my fingers, and even under 30x magnification it looks and feels like everything is right, edges meeting at 0, no burr, etc. But the thing just won't cut the way I want it to. It will cut newspaper, but not perfectly, and it will only shave hair if I really scrape.

The only things I can think of are decarb, but I ground a decent amount off the edge after hardening, and "under tempering." That is, I am wondering if I might need to temper a bit higher. I went to 400 but I am using W1 and feel like I really nailed the heat treat. I am wondering if I got enough hardness to need to temper a bit higher to get better sharpenability.

All help greatly appreciated,

John

 

[bigbcustom]

I had the same experience a while back. Looked like everything was great, but no cutting. Turned out that what looked like a zero edge was actually two bevels going down to a little tiny flat where the edge was supposed to be. Finally saw this while looking at the blade edge on under a dissecting microscope. I just hadn't sharpened enough yet. Attacked it with coarse stone for awhile then rehoned. Cut like a dream. I am not saying that this is the problem you are experiencing, but it could be.