Anealling a rasp or file

[Whistler1895]

Was given a couple of farier's rasp and learned most are likely case hardened and I should probably aneal them first. So while burning limbs i put them in them in the coal bed when everything was pretty much burned down. Let them stay there till the next morning and pulled them out. Still hot and a little bent straightened and let sit all day. My question is- could i have over done it ?

[Sarge]

That's how I anneal my rasps and files. I use the fire pit in the summer and the wood stove in the winter. Sometimes they warp but are fairly easy to straighten once they are annealed. On occasion, I've had to anneal a second time. If a good bit won't drill them, you might need to anneal again.

[Quenchcrack]

If they are case hardened, you probably won't get much of a knife out of it.  The hard layer is only as deep as the teeth on the rasp.  When you grind a bevel, you will remove the hardened layer and the knife edge will be soft.

[Whistler1895]

I've already ground one and i plan on heat treating them when i get a fire box built. The one threw a lot off long brite orange/yellow sparks soni dont think i removed much carbon. From what i can find out so far could be 1080. A good oil quinch should harden them rite up. I hope

[Whistler1895]

If anyone has any advice or suggestions please send them my way

[crashdive123]

After you harden it, run a file across the edge use some pressure.  If it skates across the surface, it is hard.  If it bites into the surface, it is not.

[1066vik]

canola or peanut oil heated up to 130-140 degrees before you quench works a lot better than cold oil or used motor oil.
those 2 vegetable oils also have a pretty high flash point and the smoke from them isn't as toxic as petroleum based oils.

If, OTOH, you have access to an actual engineered quenching oil, that will work even better -- but you still want to heat it.

heat our file up until it is glowing red and a magnet doesn't stick, then quench.
keep it moving in the oil - but only up/down or front to back - side to side like a paddle can cause it to cool at uneven rates and warp.

[Unknown]

I don't know that it needs to be said, I will anyway. If you are going to test with a file; make sure it's kinda new. I have plenty of used up dull files that will skate, or at least not cut, when a fresh one digs in like crazy.

[Whistler1895]

Thanks for all the input guys. One last question, I'm and pipefitter and was thinking of using light cutting oil as a quench. Its meant to remove heat quickly and has some sulfur in it. Any thoughts ?

[crashdive123]

It should work just fine.  Heat it up first to about 130 degrees (F).

[Whistler1895]

Thanks guys as soon as I get something done I'll post the pics

[Quenchcrack]

Whistler, case hardening is applied to LOW CARBON STEEL.  Low carbon steel is cheaper than high carbon steel.  They add carbon to the outside of the rasp in a special heat treatment called carburizing.  It usually only goes 040" deep.  If your rasp is carburized and you grind a bevel on it, the center of the blade will be in low carbon steel and will not harden.  Now if the rasp is really all high carbon steel, you are good to go.

[Whistler1895]

Ok. I guess I won't know till I know. Thx