Hardening knife blades

[Dougster]

I have the bug - badly, I can't stop making knife handles and sheathes. I want to move onto the blades, possibly... depending upon wether or not I can find someone who can harden it proerly after I've shaped it and drilled rivet holes.

Anyone out there prepared to do this? Or any suggestions? If anyone knows roughly how much this would cost that'd be great too.

 

[akraven]

How about just going ahead and doing it on your own? If you stick with the high carbon steels its not very hard to do. Do you have any room to do it? akraven

 

[C_Claycomb]

There are plenty of folks around who can do a good job. Your best bet to find them would be to go and have a look around in British Blades. There are a number of makers there who are either full-time, or very serious part timers

Doing it yourself isn't too hard, even with O-1 which is a bit more complicated than the "simple" carbon steels. The usual hitch is the need for insulating (soft) fire bricks for use with a gas torch, or the construction of a simple forge.

Cost will vary, but should work out as under 10pounds per blade whereever you go.

If you get the Wayne Goddard books on knife making, they have some great suggestions for doing it yourself. There are also plenty of instructionals and threads on the knife forums.

 

[Ogri the trog]

Have a go yourself Rich,
You'd be supprised at how many ways you can get enough heat to get the blade sufficiently hot. I use my coal fired kitchen range, but a reasonable barbeque should do it. Fabricate a bit of wind protection to keep the heat in, and a very simple blower (AKA a hair-dryer or matress pump) should be sufficient to get the blade to cherry red.
Check regularly with a magnet to find when the steel stops becomeing attracted (this is the correct temperature for hardening) - when it does, quench the blade in some hand-hot oil (any oil, from veg cooking oil to old engine oil). Have a bit of a clean up to get the blade back to bare metal and temper it. This is just trading off a bit of the hardness for some toughness so that the blade is not too brittle.
Simply heat the blade to around 200 - 230 deg C just so that it starts to turn a straw colour - and leave it somewhere to cool slowly, any electric oven should do this without even thinking about it.
The really complicated bit comes next - fitting a handle

Have a go anf have fun

Ogri the trog

 

[davek]

http://www.primitiveways.com/pt-knives-1.html

Don't need a forge just to harden.

 

[Shing]

Heat treating supplies.

These supplies will enable you to heat treat 01 steel blades, up to 3.5 inches long and 3mm thick.

Blow torch
3 insulating bricks e.g. from www.chronos.ltd.uk
Veg oil
Metal container at least 4 inches in depth ideally with lid like an old syrup tin
Pliers
wire
googles
thick gloves
gas lighter

You need to build a small enclosure with the 3 fire bricks like so

and put the blade between the bricks, heat the back of the blade, at a low heat then gradually increase it until its bright orange, its easier to see in a dark or shady area, keep the flame playing along the blade, the ideal is to heat the whole blade but not the tang, evenly and bring it up to the same temperature at the same time. Once its at bright orange, keep it at that temperature for 2-3 minutes the quickly plunge it tip down into the oil covering the blade and a bit of the tang, This is where the thick gloves come in handy as the oil with catch fire for a minute or two until it cools.

When its still fairly hot take it out of the oil and see if its straight, if not straighten it now before it cools and becomes very brittle. Clean off the oil with some kitchen roll. Use an old file to cut the blade, if it bites then its too soft, if it bites slightly but slides off then its hard and you can temper it. Put the blade into a preheated oven at 230-240C for 2 hours, take it out and cool then put it in for another 2 hours and thats HT done.

good luck

 

[Stew]

You make it sound very easy Shing!