Do I need to heat treat a file?

C

charlesbjr

Joined
Mar 8, 2006
Messages
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Hi all;

I am making my first knife from a file. But do I need to heat treat it? I was under the impression that files have already been heat treated.

Thanks.
 
charlesbjr said:
Hi all;

I am making my first knife from a file. But do I need to heat treat it? I was under the impression that files have already been heat treated.

Thanks.
Click to expand...

Yes they have been heat treated. However, some people will anneal them to make them softer so they can work them easier. Once they've profiled the file out, they then will have to "reharden" it, which means they'll need to HT it again.

Others, like Michael Morris, tempers them so that the files aren't so brittle. Take a look at his video's, they have some good info on making a knife from a file.

How to make a knife from a file
 
Mudbug007 said:
Yes they have been heat treated. However, some people will anneal them to make them softer so they can work them easier. Once they've profiled the file out, they then will have to "reharden" it, which means they'll need to HT it again.

Others, like Michael Morris, tempers them so that the files aren't so brittle. Take a look at his video's, they have some good info on making a knife from a file.

How to make a knife from a file
Click to expand...

I watched the linked video's. Am I right in assuming that once tempered, the blade is done and no other heat treating is necessary?
 
chrisa62401 said:
I watched the linked video's. Am I right in assuming that once tempered, the blade is done and no other heat treating is necessary?
Click to expand...

I believe Michael says he tempered them back to the mid 50's. As long as you don't over do it, the blade will be done once you temper it. Make it too soft and you'll have to reharden it.
 
M.M.'s method is REALLY simple, and allows him to give a lot of knife for a very low price, heat treating in the kitchen oven without a forge or kiln of any kind.
You'll probably need to use carbide bits to drill any holes for handle fasteners, though- there are some very knowledgeable machinists here, perhaps one will chime in on drilling W2 at Rc 56.
I like to soften them fully, either at non magnetic or using Tai Goo's subcritical anneal, as described in the sticky.
Have fun!
Andy
 
chrisa62401 said:
I watched the linked video's. Am I right in assuming that once tempered, the blade is done and no other heat treating is necessary?
Click to expand...

Yes. (assuming it's a decent file to begin with, like Nicholson or Simmonds) the file is already hardened and tempered, MM's process simply tempers it back a bit further so it's less brittle but will still hold a good edge. You can further soften the tang to a degree by keeping the blade immersed in water and heating the tang with a torch, then letting it cool slowly. This won't fully anneal it but will make it easier to drill. Carbide bits are still a good idea, though.

If you have some manner of belt grinder to do the blade shaping, it's a very good way to get started in knifemaking.
 
When shaping a blade from hardened steel the main thing to keep in mind is that any heating above about 500F will ruin the edge hardness. 500F sounds like a lot, but in grinding, the edge can become 1000F in a split second. The first sign is a blue color forming when you grind. That indicates you already passed the 500F limit at the edge. Once or twice, a little blue spot won't be the end of it all, but a big dark blue patch, or repeated blue spots will ruin the blade.
The standard method is to grind a few seconds, dip in water, grind a few seconds, dip in water,........

Using bare fingers will tell you quickly when the blade starts to get warm :)
 
bladsmth said:
The standard method is to grind a few seconds, dip in water, grind a few seconds, dip in water,........
Using bare fingers will tell you quickly when the blade starts to get warm :)
Click to expand...

Very true, and very important. Cool often, before you feel or think the steel is getting hot. A quick dip in water after each grinding pass or two only takes a second and will prevent problems. A couple drops of dish soap in your water will help break the surface tension and allow swarf and grit to sink to the bottom - this reduces gunk getting stuck on your blade and gumming up your belts.

I grind barehanded for two reasons - to give me an early warning of heat build-up, and because I just don't trust gloves in close proximity to fast-moving machinery.

My second reason is a topic of some controversy among knifemakers. Personally I don't like nasty scrapes on my fingers any more than anyone else, but I'm certain they heal up quicker than a broken finger or popped knuckle (or worse) caused by a glove getting caught by a belt or bit.
 
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