Thread: Old farriers rasp: any annealing tips most welcome :)

'Evening everyone,

Having escaped last month from my little apartment into a house with a nice big garage/shop, I have finally begun building my forge and collecting the bits and pieces to do some blacksmithing at home. One project that will be coming down the pipe at some point will be turning an old farrier's rasp into a knife and (eventually, once my skills have developed a bit) a razor.

Obviously I won't want to be working on the rasp as-is as it's bloody hard. Any suggestions regarding annealing it to make it workable? Anything to make sure I avoid? I am familiar with the more traditional blacksmith's approach of eyeballing temps by colour and I lack accurate high-temp thermometers, so unfortunately #s won't be of much use to me. But if you have any advice that can be related to colour or magnetic properties I would really appreciate it.

No rush at all BTW. I need to finish building the forge then get used to using propane rather than coal, which all my other blacksmithing has used, so it will likely be quite some time before I tackle this project.

Thanks

No real life experience, but from what I have read heat to non magnetic and allow to cool very slowly in something like vermiculite. Not sure if it would be different with a farriers rasp. I am curious as to what other says since always good to learn something from those more experienced.

I'm throwing this out there hoping those who can verify, or refute the info will do so. I knew an old ironworker/welder who had done a lot of time in prison. He told me, 40 years ago when I was an apprentice, that he would take files, heat them cherry red, and cover them with lime. He said, IIRC, that he'd leave them overnight and that when they were cooled off they were flexible enough to be like spring steel where if you stabbed someone in the ribs, the blade would snake around the bones rather than break.

I don't know if this method of annealing is doable, or if the results of doing it that way would be as he described. You hear so much "stuff" as you go through life.

Prison shanks are bound by a different set of rules...

As to simple annealing, yes, heat to non magnetic, at least a dull orange and allow to cool overnight slowly. Vermiculite, the micaceous stuff not the styrofoam stuff, or wood ashes will do the trick nicely. It should be soft enough to grind a lot more easily.

I would recommend removing the "teeth" of the rasp. It's too easy to leave a cold shut without realizing it and when heat treating the blades that result from the work, sometimes those shuts can lead to unwanted surprises.

"Jimmy's Floppy Shiv Co."

With prisons being such a growth industry, there's probably a buck or two to be made there.

Thanks guys - that was what I was thinking, so it's reassuring to have confirmation. And thanks for the teeth recommendation - I hadn't thought about the possibility of them presenting potential problems. Too bad as I think they would look great on the shank. Ah well...

I've quenched a knife made from a file that had cold shuts. After the quench, the blade had a couple of marble sized pustules

Originally Posted by Bruno

I've quenched a knife made from a file that had cold shuts. After the quench, the blade had a couple of marble sized pustules

Pustules?! Cripes... this is getting worse!

If the young smith held on to the hot piece too long, the tendons would contract and the grip will tighten. No letting go after that and it just keeps making things worsefrom there. Learn to use the back of your hand! Great advice.

Originally Posted by Mike Blue

If the young smith held on to the hot piece too long, the tendons would contract and the grip will tighten. No letting go after that and it just keeps making things worsefrom there. Learn to use the back of your hand! Great advice.

Reminds me of my classmate who had the brilliant idea of making an extra long power extension by putting 2 plugs on a very long cable, which he was then going to plug into a free socket on one of those power bricks with multiple outlets.

He plugged it in the wall socket first, and upon trying to put the other end in the brick, it slipped, and he caught the prongs between thumb and index finger. Couldn't let go after that. In the end he put his foot on the cable and yanked his hand loose. 3d degree burns to the bone. Good times... Good times...

Oh. He was majoring in power distribution at the time.

You mean to tell me that the hissing sound that doesn't hurt immediately isn't a good thing? Yep, good advice indeed...back of the hand.