Hello Joshua, 

I like your instincts on the torch.  Heat treating with a torch is one ugly idea that I wish knifemaking, as a whole could forget and put behind us.  What I would do in your position is ditch the wood in the forge and buy some real hardwood lump charcoal, never briquettes but real hardwood.  Wood is a rather spotty heat that will never give you the same temperatures as pure carbon, like charcoal or coke.  With wood you are using up most of your energy in burning out the moisture, hydrocarbons and resins. 

I once did a presentation on how you can get a very good knife with almost no equipment by abandoning most of the ideas about making knives cheaply that you will see on the internet and elsewhere.  I specifically urged the audience to resist the urge, and any advice, to use a torch.  I dug a hole in the ground and put a perforated pipe in the bottom, I dropped 4 to 6 firebrick to line the sides on either side of the pipe and I filled it with lump hardwood charcoal and put a hair dryer against the pipe.  With this setup, I forged a 5" hunter and hardened it quite successfully.

You do not want to grind or sharpen before tempering.  Temper the blade out and do any post hardening grinding on a new, sharp belt with a water bucket directly beside the grinder.  Take a pass, dip, take a pass dip.  Do NOT wait until you feel heat to dip.  Save the torch for differential tempering, if you wish to do that.   

Posted by: @krcashenabs

Hello Joshua, 

I like your instincts on the torch.  Heat treating with a torch is one ugly idea that I wish knifemaking, as a whole could forget and put behind us.  What I would do in your position is ditch the wood in the forge and buy some real hardwood lump charcoal, never briquettes but real hardwood.  Wood is a rather spotty heat that will never give you the same temperatures as pure carbon, like charcoal or coke.  With wood you are using up most of your energy in burning out the moisture, hydrocarbons and resins. 

I once did a presentation on how you can get a very good knife with almost no equipment by abandoning most of the ideas about making knives cheaply that you will see on the internet and elsewhere.  I specifically urged the audience to resist the urge, and any advice, to use a torch.  I dug a hole in the ground and put a perforated pipe in the bottom, I dropped 4 to 6 firebrick to line the sides on either side of the pipe and I filled it with lump hardwood charcoal and put a hair dryer against the pipe.  With this setup, I forged a 5" hunter and hardened it quite successfully.

You do not want to grind or sharpen before tempering.  Temper the blade out and do any post hardening grinding on a new, sharp belt with a water bucket directly beside the grinder.  Take a pass, dip, take a pass dip.  Don NOT wait until you feel heat to dip.  Save the torch for differential tempering, if you wish to do that.   

Thanks, Kevin! I'll sideline the torch for now and spin up the whitlox forge with some hard wood charchoal from Rural King. I can't wait to see what this thing can do 🙂

As for the torch - can you tell me where I might want to use an option like this in the future? I bought it so I could cut, weld billets, and make easy bends in other metal projects, but now I'm wondering if it could be used in other parts of knife/sword/axe making.

Also, can you help me understand what you mean by 'you do not want to grind or sharpen before tempering'? I assume by grind, you mean the final grind to the edge, not the actual profile of the knife, etc. Stupid question, I know - but I want to be sure I'm not missing anything from the masters on this forum.

Regards,

Josh King

An O/A torch is capable of creating 6,000°F in a 1/4" spot, I have never been able to figure out how so many knifemakers could apply the word "control" to this scenario.  But enough of my complaining, there are many very valuable uses for a torch in a knifemakers shop. 

For every manner of brazing or soldering a torch is indispensable.  I do also use mine often for bending and localized heating.  Yes, you can weld with it, but I find gas welding best for smaller stock, tacking together billets is chore with a torch, but a breeze with arc welding. Cutting is definitely useful, but as soon as I got my plasma cutter I pretty much forgot where I put my cutting torch head.

Now- there are some heat treatment operations that will work.  For differential tempering, nothing is nicer than a torch for painting that spine blue.  I also will use a torch to heat treat my damascus fittings.  In this case the heat treatment is not for performance like in the blade, but to enhance the etch and increase scratch resistance, so the same concerns are not as bad.  And fittings are small enough to easily heat with a torch flame. But one of the main reasons I do this is atmosphere control, which is a huge issue with torching something the size of a blade.  Before I go for the high heat on my fittings, I adjust the torch to a very rich carburizing flame.  This will cover the fitting in a thick layer of carbon (soot), that will protect the part, which is often beyond a 400X polish, while heating.  The soot doesn't really burn off until the part is almost to temp, and then it is quenched before I get any scale or decarb. 

On my comments about grinding, I was referring only to operations that one would save until after hardening, like thinning down the bevels of a thinner kitchen knife or razor.  All heavy grinding should be done before any hardening treatments.  And anything done after hardening should also be done after tempering.  Adding strain and stress risers by grinding in the fully hardened condition, or delaying the tempering to do so, would be ill-advised.        

It's replies like this that bolster my confidence in the ABS and reassure my decision to join.
Thank you VERY much for the thorough answer!