Annealing an old file

MyNameIsBo

MyNameIsBo

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Hello again everyone. I'm struggling to anneal a file that I want to turn into a knife. I have a propane torch, the kind that screws onto the green camping propane tanks, and I can't seem to get the whole file hot enough with it. Do I need a bigger torch head, or do I just need to be more patient about the process? I spent about 20 minutes slowly going back and forth over the length of the file and it never started to glow at any point. Thanks!
 
Hey Bo,
Like I said in our earlier conversation, a plumber's torch is not the best heat source for a large knife. Using MAPP gas is a little better. A Prest-O-Lite torch works fine.

There are some "tribal" methods of annealing a file. The results are sort of variable, but what some folks do is build a nice fire in a little pit and get some wood burning. When there is a good bed of coals, put the file in and let it sit there. After a while, burry it in the coals and ashes and come back tomorrow when everything has cooled. It may still be hot, so be careful. Take it out and let it cool to room temp. It should be softened.
Is it perfect - NO ... Will it work - YES.

A better way is to use an A-O welding torch and a rosebud tip. That will heat the blade just fine for annealing and can be used to do HT as well.

There are several threads and tutorials in the stickys about making a file knife. Using the Custom Search Engine will also find them.
 
Last edited:
Stacy E. Apelt - Bladesmith said:
Hey Bo,
Like I said in our earlier conversation, a plumber's torch is not the best heat source for a large knife. Using MAPP gas is a little better. A Prest-O-Lite torch works fine.

There are some "tribal" methods of annealing a file. The results are sort of variable, but what some folks do is build a nice fire in a little pit and get some wood burning. When there is a good bed of coals, put the file in and let it sit there. After a while, burry it in the coals and ashes and come back tomorrow when everything has cooled. It may still be hot, so be careful. Take it out and let it cool to room temp. It should be softened.
Is it perfect - NO ... Will it work - YES.

A better way is to use an A-O welding torch and a rosebud tip. That will heat the blade just fine for annealing and can be used to do HT as well.

There are several threads and tutorials in the stickys about making a file knife. Using the Custom Search Engine will also find them.
Click to expand...
Got it, thank you so much for the reply! I'll see what I can figure out and be sure to post a WIP thread on the knife. I'm super excited to get this all going!
 
Check with friends and neighbors. Chances are good that someone very near you has a welding torch or a Prest-O-Lite torch. I would bet there are at least three in my neighborhood.

I forgot to list the "Weed-Burner" method. Buy a cheap weed burner at HF and hook to a BBQ propane tank. It will work for annealing. It can be used for HT if you are skillful.
Brace or clamp the torch so the flame is shooting horizontal and work the file in and out the flame.
 
If you have a heat-reflecting surface like a ceramic block, or fire brick, you can get things a lot hotter.
Just holding the flame on the metal unsupported won't work.
 
Stacy E. Apelt - Bladesmith said:
Check with friends and neighbors. Chances are good that someone very near you has a welding torch or a Prest-O-Lite torch. I would bet there are at least three in my neighborhood.

I forgot to list the "Weed-Burner" method. Buy a cheap weed burner at HF and hook to a BBQ propane tank. It will work for annealing. It can be used for HT if you are skillful.
Brace or clamp the torch so the flame is shooting horizontal and work the file in and out the flame.
Click to expand...
I think we actually have a weed burner at my family farm. I'll give that a try!! I also found this at harbor freight when I googled Prest-o-lite torch, wpuld this work? Also, is that something that uses oxygen and acetylene? Thanks again!
 

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Bill DeShivs said:
If you have a heat-reflecting surface like a ceramic block, or fire brick, you can get things a lot hotter.
Just holding the flame on the metal unsupported won't work.
Click to expand...
Got it, I'll see what I can find. Thank you!!
 
I do a lot of work with vintage files. To anneal, I put them in my ht oven @900 degrees for an hour, then let them stay in the oven overnight while it cools down. Heat treating/quenching/tempering might be an issue with you if you don’t have an oven. Just another suggestion…
 
godogs57 said:
I do a lot of work with vintage files. To anneal, I put them in my ht oven @900 degrees for an hour, then let them stay in the oven overnight while it cools down. Heat treating/quenching/tempering might be an issue with you if you don’t have an oven. Just another suggestion…
Click to expand...
Do you have a suggestion for good oven? I'm on a tight-ish budget, but I certainly want one at some point so I can start setting money aside for one.
 
MyNameIsBo said:
Do you have a suggestion for good oven? I'm on a tight-ish budget, but I certainly want one at some point so I can start setting money aside for one.
Click to expand...
I’ve always used Evenheat ovens. They’ve worked just fine for me. Other good brands out there….everyone has their own opinions of course. Start saving your pennies!
 
MyNameIsBo said:
Do you have a suggestion for good oven? I'm on a tight-ish budget, but I certainly want one at some point so I can start setting money aside for one.
Click to expand...
The oven mentioned is in the $2,000 range. Many other tools you need before a $2K oven. Good luck with your file knife - looking good in the video.
 
Ken H> said:
The oven mentioned is in the $2,000 range. Many other tools you need before a $2K oven. Good luck with your file knife - looking good in the video.
Click to expand...
That's true, there's a lot I still need. Thank you!!
 
The cost of equipment to make knives can be high. In the beginning using a local maker to do the HT tasks will get you started with little more expense than a six-pack of beer.

The old book, "The $50 knife shop" was good, but the valuation is no longer accurate.
 
Jarod Todd is offering discounted (single temper, no straightening and no tempering to specific HRC #s) and premium heat treating services now, too!

You can also look up a "Fire Brick Forge" where you take several fire bricks, make a small chamber out of them and use the torches. The fire brick helps retain the temperature and make it a little more even. I ended up building my own HT oven for about half of what a commercially available one would have cost me. $1200 for a 27" x 7" x 6.5" chamber with a WiFi Ramp/Soak PID. I put it to use for the first time with some 24" long OAL blades and it worked great! Glad I went wit the 27" deep due to the foil pouches the stainless blades go in to; just fit inside front to back!
 
Stacy E. Apelt - Bladesmith said:
The cost of equipment to make knives can be high. In the beginning using a local maker to do the HT tasks will get you started with little more expense than a six-pack of beer.

The old book, "The $50 knife shop" was good, but the valuation is no longer accurate.
Click to expand...
I might still see if I can find a copy, I'm sure it still has useful info!
 
Taz said:
Jarod Todd is offering discounted (single temper, no straightening and no tempering to specific HRC #s) and premium heat treating services now, too!

You can also look up a "Fire Brick Forge" where you take several fire bricks, make a small chamber out of them and use the torches. The fire brick helps retain the temperature and make it a little more even. I ended up building my own HT oven for about half of what a commercially available one would have cost me. $1200 for a 27" x 7" x 6.5" chamber with a WiFi Ramp/Soak PID. I put it to use for the first time with some 24" long OAL blades and it worked great! Glad I went wit the 27" deep due to the foil pouches the stainless blades go in to; just fit inside front to back!
Click to expand...
I was actually going to pick up some fire bricks today for that exact purpose! Thank you for all the useful information 🙏
 
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