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I attended a hammer-in recently at Anvil Academy in Newberg, Oregon. One of the demonstrators (I'm an idiot because I lost his card) made a knife from 1095.  He used the tendency of flat bar steel to "mushroom" when struck on edge to his advantage, and crafted an interesting handle for his one piece knife.  One thing he mentioned was the ratio of about 1:8 in thickness to width, as being a dimension very prone to mushrooming when struck on edge.

My current problem for which I could use some advice:

I want to make a rat tail knife from an old file. It seems the dimensions are close to 1:8, and it really wants to mushroom as I try to draw out the handle to square.

How do I combat this? So far I've tried correcting the mushroom by striking on the flat side, and knocking in the corners with softer blows.  I probably still got some cold shuts.

Is there anything else I can do?

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This is a two steps forward, one step back process. You should expect to spend as much time flattening it as you do drawing it down on the sides.  It can be done; I make rasptlesnakes from farrier rasps and that includes making an 8" rat tail for the bottle caps to fit on and farrier rasps are even wider than most files.

A few things to keep in mind: File steel has a limited forging range do NOT try to forge it too hot or too cold. Do not let the mushrooming grow before trying to hammer  the piece it back down flat, it should be flattened every heat!

How much experience forging do you have?  Knives are not beginner projects.

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This information has been talked about many times.  

If the metal is not having the center of the bar effected with the hammer blow the edges will indeed upset because the pressure is not getting to the center of the bar. 

this can be helped along with a more driving blow.. Lighter hammer moving faster.. or a heavier hammer.   The lighter hammer with a longer handle is what most do and this will take care of the problem. or help to minimize it. 

There is also working over the horn or 1/2 on 1/2 off to get better penetration into the metal. 

One of the other factors is not getting a thorough heat on the work piece.  IE the edges are hotter than the center. 

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Thanks for the input folks! I was out of town so didn't get a chance to read or reply.  I ended up better off than expected by doing what it turns out you all mentioned -- I switched to a longer handled hammer with a flat face on one side and a domed face on the other, worked over the horn, and at an orange heat correcting any mushrooming on every heat.

The knife is still pretty rough, but I'm pleased with my 1st attempt.  I'm going to straighten and re-bend the handle into more of a teardrop and take out the kinks in the curves.  If you look closely at the handle, you can see a thin line running along the length. I'm hoping this is a shallow cold shut that won't hurt functionality... Guess I'll find out!

I figure it'll be an OK knife after some hot filing the blade to shape and finishing with a 1x30 belt sander.  I left extra "meat" at the tip because I didn't want it to get too thin and possibly break in the next steps.  I usually use coal or charcoal, and am learning fire management the hard way.  Putting a work piece too deep (i.e. in the oxidizing zone) and cranking too long or too hard on the blower can make a project disappear. I had the rat tail drawn out 11 inches, then screwed up and burned through at the halfway point.  Thankfully there was enough extra material in the file to just draw out some more.

My daughter recommends at least several heating/cooling cycles, oil quench, then tempering in an oven.  I'm hoping to get back to this project tomorrow.

RoughRatTailKnife.jpg

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Just remember that the tang does NOT need to be quenched and a soft tang will be less prone to breaking that a hard one.

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Thanks for that advice Thomas.  With your advice, I now won't quench the tang and that could save this piece from cracking.  I had some house guests over Thanksgiving and one brought a nasty stomach virus that took out all but one member of my family. I'm finally over it and hope to get back out in the shop tomorrow.  I'll post a pic of this finished knife or the disaster if I should mess it up. :D  I love working with hot metal and learning from you all.

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