Well somewhere during the heat treating process of the very first knife I've successfully forged, it acquired a slight side-to-side bend. I'm not sure where in the process it occurred, but it was flat after forging, and I didn't notice the slight bend until I pulled it out of the toaster oven once tempering was done.

 

It's slight enough that a few good hammer blows cold should straighten it, but is this wise to do on a blade that's just been hardened? Should I heat it back up to forging temperatures then straighten it? If so, how do I go about heat-treating it again, wouldn't quenching it again make it too brittle?

 

If any more information helps, it was forged in a coke-fired forge, and for hardening it was heated in an electric heat treating oven.

Just chuck it back in the oven at tempering temp, then get a little piece of leaf spring etc... with a slight curve. I have one roughly 300mm long for this, you then use a metal clamp and make it straight or just slightly bent the other way and put it back in the oven leaving it for 30min then let it cool slowly. This is what I did with a warped cooking knife recently.

A trick that I was shown was to make a hammer from a rock drill with a carbide bit still in the end. Make sure the carbide is radiused (no sharp edges).

Tap the side of the Blade cross-wise to stretch or shrink until straight. Tap the Blade length-wise to take out a twist. This is done cold.

 

Welcome to the world of the unknown :) :)

 

Neil

The warp is most likely due to stress in the blade prior to hardening...It can also be saused by sticking the blade in the quench so one side hits quenchant more than other side. In the knife making lessons and heat treat stickies there is info on normalizing,,

For me, as I have a hydraulic press, I quench for 8-10 seconds in oil, then immediately put the blade btw (2) 1.5" thick al plates and press for several minutes or so until the blade is cool. The same effort could be done in a vise located near the quench tank. I usually quench and straighten twice till the steel is cool on the second pass. Straightening after temper is a pita, and while it works sometimes, is a crap shoot. Better to do it asap imho.

John

A trick that I was shown was to make a hammer from a rock drill with a carbide bit still in the end. Make sure the carbide is radiused (no sharp edges).

Tap the side of the Blade cross-wise to stretch or shrink until straight. Tap the Blade length-wise to take out a twist. This is done cold.

 

Welcome to the world of the unknown :) :)

 

Neil

 

 

hitting any hardened blade is asking for fractures or shattering  the blade,  you have been warned.

This is my brake drum forge. I made for around $50. I start it by a little bit of charcoal and then once the charcoal is hot enough I will add the coke. I removed the black rubber pipe where the forge blower is. (which is an air matress inflater, thats temporary) I know it isn't the best forge. But it's all I could do.

Edited April 20, 201511 yr by ThomasTheRebel

ThomasPowers

Well you need to slit opposing sides or add a fence so you can pile fuel up and slip your stock through the middle of the hot spot,  I did a fence and my small brake drum forge became my top billet welding forge.  Looks like too much air do you have a control system worked out?

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Frosty

That's a good start It'll let you make more than enough items to sell and upgrade. Keep your eyes open for a steel table or cart, washing machine lids work a treat but you gotta make legs. Then mark a circle the drum will drop into but the rim won't pass through. Cut the hole and drop the drum in. Now you have a decent sized forge, large fire pot and plenty of room to store working fuel, lay tools and support stock you're working on.

The cinder blocks aren't great for table legs but will work if you can get them tall enough but you'll still have stability problems.

I have 3 of those 12v inflate all blowers, they're de BOMB for remote set ups. All a person needs is a little black pipe and a camp fire to be up and forging. If I were working a coal forge and that's what I had I wouldn't replace it unless something much better fell in my lap.

Frosty The Lucky.

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ThomasTheRebel

Posted 10 minutes ago · Report

  13 minutes ago, ThomasPowers said:

Well you need to slit opposing sides or add a fence so you can pile fuel up and slip your stock through the middle of the hot spot,  I did a fence and my small brake drum forge became my top billet welding forge.  Looks like too much air do you have a control system worked out?

 Thanks! I do that. The air is fine. I am getting a new forge blower anyway:)

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