Rasp HT trouble

[trogdorr]

So i have this rasp knife I've been working on and no matter what it doesn't want to harden. It's a bellota, and I forged the teeth flat and everything else was stock removal. Ive tried an uninterrupted quench into soapy, salty water and that didn't work either. It failed the file test, it bit into both the edge and the flats. Ive heard of rasps being case hardened but why would the flats reharden where i didnt remove any steel?

 

[Stacy E. Apelt - Bladesmith]

If the HT isn't working at all, the rasp was probably case hardened.

 

[samuraistuart]

If the HT isn't working at all, the rasp was probably case hardened.

....or decarb layer.

 

[trogdorr]

But if it was case hardened wouldn't the areas where nothing was removed re-case harden?

 

[DEllis]

If you forged it, you may have burned off the carbon case layer......it's very thin.
Darcy

 

[Fish30114]

I have worked with a few Bellota rasps and haven't had any issue with getting them hard. I did not do any forging on them though. I simply ground the blade into the rasp, and then went about my hardening work. I heated them to the proverbial cherry red, and then quenched them in pre-heated Peanut Oil--I pre-heat by heating a 1/2" rod til red and stir it around 3 or 4 times, heating between each pass. I know that there are many different rasps within a given line, and the couple I fooled with may have been different from yours--just wanted to share my experience--I've made quite a few knives out of Farriers Rasps, mostly Hellers, but a local machine shop I'm friendly with has confirmed what my calibrated files have told me, mine have been coming out at 59-60, this after two 1hour tempering cycles at 425

Good luck to you!!