Help-difficulty with stock removal edge

marekz

marekz

Joined
Jun 16, 2008
Messages
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Hello all, Ive got myself in a rut. Im practicing making stock removal knives. The problems is getting a sharp edge.Ive made stock removal knives in the past but lately , ive been having this problem. Im getting really frustrated. I start off with a 3/32 o1-precision. I thin it down a bit ( as it is a kitchen knife) , i get the edge centered,then I go to putting a edge on it , then after heat treating, I start back on the edge.. I cant seem to get the edge sharp. I end up taking alot of steel off the blade. I burr up one side and start on the other side- it ends up dull again. So it try different methods without success. Any advice or references would be helpful and appreciated- Thanks- Mark
 
My method is similar to yours, but i don't burr up one side and then switch, I do a pass or two on each side at a time (instead of 50 passes and then switch to the otherside, which is what you are doing?), and work through the grits on my stones. It seems to work for me.
 
I HT my 3/32 blades before I grind anything except a 45 degree on the edge. What are you using to HT them? It may not be getting hard enough as O1 needs a 20 minute soak.

I also take my edge down to .007 before I put the final cutting edge on. Since I leave them at 61/62, the edge holds up fairly well. How thick are you leaving your edge before you sharpen it?
 
If you are putting an edge on before HT on a .900 or thinner blade, you will have to remove a lot of decarbed steel to get an edge. Either profile the knife and grind the bevels after HT, or grind the bevels only and leave the edge at .030 minimum ( don't do an edge bevel).

Once the knife is hardened, re-grind the bevels with a 220 Norton blue belt...avoiding heat.....don't set the edge yet, but grind the bevels to nearly an edge (.010). Then repeat with 400 grit, and set the edge. At this point there will be a burr on the edge that makes it not seem sharp...don't let it fool you. Strop the blade on a charged leather strop, or buff with green chrome or matchless white. A pass or two on each side will pop off the burr and make the knife crazy sharp. Be careful, as the knife will go from barely cutting to bone deep slicing in about 2 seconds.
 
Thanks everyone
Zach, no i dont take off stock from one side by doing multiple passes, I try and keep it down to 3 passess tops ( sometimes 4 if im feeling the groove.lol) on a side before switching over, but yes you are correct about sharpening. I usual make enough passes to get a nice burr on the opposite side. I dont know for sure, but If I were to guess, I would say approx 8 passes to get the burr i want- on a 60 grit.That may be a factor, I could see how the edge may get off center- Thanks

Jaw, im using a forge- heating to non magnetic- then leaving it in for about 20 seconds more. I use canola oil at approx 180*-200* to quench. I then temper it x 2 at 400* x 2 hours each- letting it cool in the oven to room temp.

Stacy, i do the bevels to about .006 and do an edge bevel down to approx .04 before heat treating- I use a 60 grit to get down to the edge. That may very well be a significant part of the problem.. I do use a norton.- thanks Stacy- good stuff

Sam , I start with a 60 - 220 - 400- Thank

Thanks you all-Mark
 
Last edited:
marekz said:
Jaw, im using a forge- heating to non magnetic- then leaving it in for about 20 seconds more. I use canola oil at approx 180*-200* to quench. I then temper it x 2 at 400* x 2 hours each- letting it cool in the oven to room temp.
Click to expand...

If I am reading this right, non-magnetic plus a 20 second soak just ain't gonna make it happen for O-1. O-1 needs to be somewhere between 1475-1500 with a minimum soak time (at temp) of at least 5-7 minutes in order to get all the goodies into solution. The Canola will work fine with O-1 providing you have the steel where it needs to be prior to quenching.

As Stacy said, de-carb can make you think you didn't do something right, especially when heat treating in an open forge.

Knife making is kind of like life.......... We need to continue to fine tune everything every day.

Robert
 
Thanks Robert, I need to keep the o1 in there for 5 - 7 minutes after non magnetic. I usually do soak for longer. I have been experimenting on o1 for fun. I use smaller pieces. Im trying to learn/understand how to distinguish grain structure at different soaks and using different quenching fluid. I see now that I have not soaked this actual working knife long enough- Thanks for the help-Mark
 
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