How Will I know its time to heat treat my fixed blade?

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supernate1990

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Apr 26, 2011
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Hello,

First time making a fixed blade knife, using the stock removal method with O-1 Tool steel. I have been grinding and filing it for probably 12 hours now, and was wondering how do I know when its time to heat treat it? thanks
 
You want to leave the edge about the thickness of a dime so that the edge doesn't warp when it gets quenched. The more you get done before its hard the easier it is to work with. Once its hard you will put the final finish on it which will remove scale formed during heat treat. There is the shop talk section of the forums where you will probably get better answers.
 
Read the sticky threads on top of this forum. There is a ton of info.
 
supernate1990 said:
Hello,

First time making a fixed blade knife, using the stock removal method with O-1 Tool steel. I have been grinding and filing it for probably 12 hours now, and was wondering how do I know when its time to heat treat it? thanks
Click to expand...

When your fingers are crippled and permanently bent to grip a file is often times good enough. ;-)

A better answer is "It depends." If you're making a necker with a a 1.5" blade then 12 hours of filing may be overkill. If you're making some sort of huge knife then 12 hours may not be out of place.

You stated that you've been grinding and filing for approximately 12 hours. This means you haven't yet begun to use sand paper. That should be good for another 12 hours. ;-)

- Paul Meske, Wisconsin
 
basically when it's done. You're edge will be missing the actual edge and will still have a bit extra over that but not a lot. The shape is done, everything's smooth and clean. It doesn't need a super fine finish, but a 120-220 grit finish helps reduce how much you have to do after HT and makes it easier to see problems before they're a lot tougher to remove.

My last half dozen knives have been taken a lot closer to done before HT than I did in the past, and it's definitely made my life easier. My time from taking a heat treated knife to ready to mail has been cut drastically along with far less sandpaper used, fewer belts worn out and an overall increase in productivity. For obvious reasons, steel's easier to work before it's hardened. A scratch heat treated just like the higher surfaces, so now you've got to grind all that extra steel, now hardened, to get below the scratched point PLUS clear off the decarb layer at its base. trust me, as someone who used to be insufficiently anal before HT, it's easier and faster to do the work first and just be cleaning up the results of the HT after.
 
If you're using flat ground O1 and doing stock removal, you are going to wind up with an essentially stress-free knife after you've shaped it. (If you had forged it, you would have obviously stressed the metal through your various manipulations.)

As your piece is (essentially) stress-free, you probably don't need to keep the edge so thick before you heat treat it. I differ from the standard approach in this, but I've made several knives out of O1 by stock removal, and I've never had any appreciable warping out of the quench. I form the blade and even go so far as to actually sharpen it up to 1000 grit (on stones) *before* I heat treat. It's a heck of a lot easier to remove metal when your stock is annealed than it is after. The blade has been hardened and tempered.

After HT, it's relatively easy to scrub off the quench-crud and proceed with the sharpening and polishing.

Now, having said all that, I would recommend doing it the way "everyone else" does it, THEN try it this way. I don't want to be responsible for you messing up your first blade :)
 
Read the sticky "How to instructions for making a knife" and use the conventional approach, leaving some thickness on the edge before HT. Stacy describes the process in detail in the sticky.
 
Thanks for the tips everyone! It's a 12in, 1/4in thick piece. I'm duplicating the beck survival knife, made famous from the movie the hunted. I started with 100 grit paper and will b switching to 220 shortly before HT.
 
220 leaves an acceptable finnish, but going finer might be what you're after.
A 600 gritt going from the ricasso to tip will be a good one.
HT and re-sand 600
 
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