A2 and O1 stock removal - before sending to heat treat questions

Josh Muller

Josh Muller

Joined
Jun 22, 2003
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i read the post on how much work should be done before sending a blade in for heat treatment, and i gathered that its generally better to send in blanks (shape of knife cut out, but no bevels applied) to help slow later grinding, and help minimize warpage.



but as im hacksawing out the blade shapes, im having a hard time getting all the knives out of one bar that i want, so id like to be able to use something that can really cut thin curves and curners. i have a remgrit hacksaw wire, but it cuts twice as thick as the hacksaw blade, both taking off more metal and taking considerably more time and effort.

my basic question is this,

will the heat damage caused by using a dremel or similar tool (high speed rotary) be detrimental to the knife when it goes to be heat treated? specifically for A2 and O1 steels

thanks for any info or opinions :)
 
It won't hurt the blank.

Dremels and like tools tend to burn out easily cutting steel. I use a 4" DeWalt offset grinder with a metal cutoff blade. Mine is 8 or 9 years old and going strong.

I have not had trouble with heat treating blades that I have ground to shape. I don't do much O1, but I use D2, A2 and S30V as my standard stock. Unless you have really good equipment and lots of new belts, I would not advise doing all your grinding on hardened tool steel.
 
I don't know how you are going to do the bevels after heat treating, but if it's to be by hand, you had better do all that before HT, as you'll not be able to after.

If you're going to use a grinder, then ignore this, but make sure you don't get those blades over 350-400 when grinding on them. It can happen in seconds, especially along the edge, or at the point, and will ruin the temper in those places.:eek:
 
I use a lot of O1 and have also started forging it, but in the main I stock remove it. I grind my blades to within 80% (rough guess) of my final bevels before doing the quench. On smaller knives I go to probably 90% of the final bevel thicknesses etc. I take the grinds only up to 80 or 120 grit and start grinding with 80 grit after HT.

I figured that in my own workshop, any problems with warpage seems to be associated with mishaps with the heat treatment. Uneven grinding can cause warpage problems, but I have learnt to keep things equal on both sides, - grind shape, grind heights, etc. I even grind stepwise on each side, a bit at a time, constantly swopping from side to side to prevent any overheating / undue stress on either side. So the uneven grinds issue is in the past for me.

Another thing to consider - warpage post hardening tempering is common enough for me, I learnt to bend the blades back to true using simple methods. Its not like you have to grind the whole shape back to true again !!! :eek: Is it more effective for you to consider this - learning how to straighten the blades ?

My biggest fear in hardening / HT is breakage. But all my knife designs don't have any sharp corners or potential stress risers, so I rest easy on that as well... make sure the quench isn't too violent. Ie.- pre-heat the oil, and stay away from water / brine quenches till you are more experienced. Hope this helps... Its not as hard as some make it out to be. Cheers. 0Jason.
 
I'm with these guys - do your grinding before HT and finishing after. I grind to 400 before HT and go from 320 to finish after. Pay attention to what Jason said about his grinding process; that works.

As to cutting out your blanks; suck it up man. :D You're best off getting a band saw but that won't help you much more than easing the pain of cutting; you'l still make a bunch of straight cuts. You're going to have to lay out your blanks to allow for that, is all I can suggest. You'll eventually find uses for all the cut off scraps - everyone does and you've probably see some of the results here. Damascus, tiny knives, belt dressing tools. It's all good.
 
HEy Dave - belt dressing tools.....?? Go into this a little. Harden the tool steel then do what with it?
 
Brian I just take the burr edge of a scrap piece of steel and use it to "grind" off the surface of the belt. Abrasive goes flying and the belt comes out cutting like new. I've managed to extend the life of the belts three or four times by doing this.

So far I've just used whatever scraps I have laying around but a couple of them are going to get "sharpened" and hardened for that specific purpose. We'll see if it works. ;)
 
Thanks Dave - You do this on the lower grits only right? What belts do you use?
 
See again, this is why I love these forums. I'm trying to help out another newbie here, and voila. I check out one of the responses and its got the answer to one of my own (unrelated) questions... :eek: :D

(Its about the belt dressing tool and the belts that Dave uses...)

Sethmurdoc, I did forget to answer one of your other questions. Regarding getting the most patterns out of your sheet steel stock, I suggest stepping away a little from the mentality of wanting to use every possible square inch of the steel. It is a philosophy that plagues newbies, and I myself have only just learnt to let it rest.

Put it this way. stock removal is all about "wasting" the unwanted steel to sculpt a good, no, GREAT looking and performing knife. You can buy steel for a few extra $$ any day. MAKE THE KNIFE SHAPE YOU WANT. Yes, use steel economically, and smartly, but don't alter / modify your knife design and use excessively time-consuming methods to save a couple of bits of steel. After all, you wouldn't leave excess steel on your blade and end up with a fat blade, JUST to avoid hogging off some steel. Pride yourself in how much steel dust you can put on your shoes !

But keep all those scraps of steel. I do. Its amazing what you can turn all those scraps into. (One day you might be forging damascus, and O1 scraps would make an awesome cable-like billet or a fantastic mosaic bar !!!)

If you do want to work A2 as well, remember that it is an air-quenched / gas-quenched steel. Because most comemrcial Heat Treaters use vacuum furnaces and inert gas quench (eg.- nitrogen) you can finish A2 pretty much up to 98% of your final finish. Most people I speak to who use A2 say that they encounter little warpage. After HT you might just need a brief session with your final grit sandpaper to remove the slight surface oxidation and to touch up any dings and knocks from the Heat Treaters.

Good luck. Jason.
 
thank you for all your replies :D

i'll get them about 80% of finsihed before sending them in.

when i made my initial designs, im not going to lie, i used the tmbm handle from busse as a basic pattern, albiet smaller and with a different curvature. the basic 2 hump swag backed ricasso area is present, and the eu17 style center finger hump is present for the belly of the handle. to stay with the style, a lot of the designs have a forward finger rest on the spine, createing an overal spikey profile. is this what you meant by sharp corners? there are no squared edges on any of them, but there are definitly some spikey edges...


i think next time im going to space them out considerably just to make it easier on myself. thank you for the good advice concerning it :D
 
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