Fully shaped and finished?

S

ScottEnglish

Joined
Apr 11, 2020
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Can you fully shape and finish a blade before heat treatment?

To put the above question in to context, I will be shaping my knife only with files. The metal will be finished by draw filing with a long angle lathe file.

Thanks.

Scott
 
You need to leave a little for after HT. You will need to finish with sand paper and/or stones.
 
Thanks Ruari. Could the scale be removed by an acid, say vinegar, rather than by sanding? If I do a good job of drawfiling the blade it would be satisfying to retain the filed finish when the knife is complete.
 
I send mine out for professional heat treat service and they specify a minimum edge thickness to avoid it coming out like a piece of bacon.
 
If you go down too thin before heat treat, the edge will warp or crack like others have said. There are products to help with scale/decarb when heat treating, but most recommend to remove metal after heat treating to eliminate these issues even if using those products. Acid or vinegar won't really work to remove decarb and will leave the surface rougher since it is chemically eating away at the surface. You can use EDM stones or sandpaper, but I wouldn't want to spend the time to remove it that way!
 
If grinding before HT, to keep your edge around .03” thick BTE. I’ve made the mistake of going too thin and made a lot of extra work for myself. The thinner you go, the easier it is to overheat.
 
How far would be reasonable to take it before heat treating? 120 grit? 220grit?
Reason I'm asking is I currently working on a couple of cleavers and hand sanding is such a PITA on hardened steel. Took me forever to go from the 120 grit belt finish to 180 hand sanded and then on from there. Currently sitting at about 4 hours of hand sanding, and have one to 600grit and the other at 220.
 
I just HT'd some damascus pieces and used a graphite spray lubricant (B'laster 8-GS Industrial Graphite Dry Lubricant) on them and they came out of the HT fairly clean and without a ton of scale. That may be another option is to use? I don't know if it prevents decarb or not and works on carbon steels.
 
ScottEnglish said:
Can you fully shape and finish a blade before heat treatment?

To put the above question in to context, I will be shaping my knife only with files. The metal will be finished by draw filing with a long angle lathe file.

Thanks.

Scott
Click to expand...
I think it depends a lot on whether you're using oil or air to quench
 
Hello Lorien. The steel I am using is 1084. You are recommended to quench it in oil.

Update

I have just been reading about the heat treatment method for kukri knives. Would this work on 1084 steel? I wonder if this method would enable me to fully shape and finish the blade, apart from the cutting edge, prior to heat treatment?
 
Last edited:
ScottEnglish said:
Hello Lorien. The steel I am using is 1084. You are recommended to quench it in oil.

Update

I have just been reading about the heat treatment method for kukri knives. Would this work on 1084 steel? I wonder if this method would enable me to fully shape and finish the blade, apart from the cutting edge, prior to heat treatment?
Click to expand...
in that case I wouldn't do anything more than profiling it and drilling holes first
 
Shaping should be absolutley no problem pre heat treatment. As others have said, you can get some real problems if you take the bevels too thin before though.

I recently tried pushing my luck, and went to redo a 52100 blade that was originally done in a forge, and it turned out wasn't going to perform like I wanted (big surprise, everyone saying a kiln is necessary for a good ht was right). Anyway, the edge ended up looking like a bunch of s's. I just ended up having to throw it away. Which I guess is better than not having a good heat treat.

What I recommend is try sanding the flats of the blade up to at least close to where you want to finish the blade, so you can at least save yourself as much work as possible. Also maybe look into either getting some anti scale, or stainless steel foil. Either of those will help with decarborization at high heat, and also keep oil from polymerizing onto the blade when you quench.
 
Blankblank said:
…. Also maybe look into either getting some anti scale, or stainless steel foil. Either of those will help with decarborization at high heat, and also keep oil from polymerizing onto the blade when you quench.
Click to expand...
Don’t use foil for 1084 or other oil quench steel. It will interfere with the cooling rate.
 
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