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Roger
12-14-2010, 03:09 PM
1- I have a lot of old coil and leaf springs. I want to use them to forge decent working knives. Supposedly that sort of thing is usually 5160 but what else could they be made of and what sort of HT temperatures should be used? Or just go to non-magnetic?

2 - I have an idea for a heat treating oven I can afford. I can control the heat in my propane forge from 1000-2100f by varying the inlet pressure of the propane. Using the dutch oven principal of baking I'm thinking of putting a 4" round section of Sch. 40 pipe, welded shut at one end with a hole for a thermocouple, inside the forge. I'll play with the propane pressure till I can get a fairly stable heat. Anyone think this might have a chance of working?

Thanks, this is a great forum.

rob45
12-14-2010, 05:02 PM
1. Can't help with the mystery metal. Could be anything!
Mystery metal will require experimentation.

2. A lot of the swordmakers out there use the same principle you're mentioning.
Their usual setup is a 55 gallon drum (on its side) lined with ceramic blanket.
A pipe is suspended in the center; no front opening except for the pipe.
The rear of the drum (not the pipe) has a small exhaust port (necessary when using gas).
The tuyere (burner port) on most are located up front for easy access to the burner. Those claiming the most successful designs usually have a heat shield of sorts in front of the flame so as to even heat in the chamber and minimize hot spots in the pipe itself. IOW, no flame on pipe = more evenly heated pipe?
But I have to wonder if placing the tuyere at a different angle wouldn't accomplish the same results with simpler construction.

Nevertheless, if it works for people making $3000+ swords, I don't see why you couldn't make it work on a smaller scale. As usual, forethought and experimentation.

Good Luck,
Rob

Doug Lester
12-14-2010, 07:23 PM
With old springs you can be rather certain that they have enough carbon in them to make decent knives. The problem with old springs is that they can contain stress fractures that can ruin a blade. You will have to check your heat treating with each different spring but each spring should give you several knives. I usually speak against mystery metal but it's hard to tell someone not to use it when they have a plenty of free, or at least paid for, steel at hand. I have a piece of 1" rebar that I'll probably have to start using for knife making. It's probably plain carbon steel; it does test out as being able to harden so I'll end up using it. Just not looking forward to breaking down a six foot long, one inch diameter steel bar without a power hammer or press but the thing keeps looking at me every time I go out to the forge.

Doug Lester