Farrier rasp HT question

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Jason Fry

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Alright, folks, I'm no newb, but I've stumped myself. Making a couple of blades out of a customer's farrier rasp. 1/4 thick in the middle, tapered tang and distal taper. I've got a digital oven and 10 second oil from Maxim. Both 1475 and 1500 austentizing temps didn't make for a hard blade. Sure hate to have to go brine, don't want the tink fairy on a customer's steel. Any ideas?
 
Could it have been a case hardened rasp? Do you have some cut-off pieces from profiling that you could quench test in water to see if they harden? Maybe try to spark test? 10 second oil should harden at least the edge of any 10 series or W steel at that thickness.

Other thoughts: can that oil be preheated for a faster quench? Or, what if you coat your blades with a very thin wash of Satanite to increase surface area, may help quench faster?

My feeling is still that this is not high-carbon. Good luck!
 
I'm tending to lean the same way, Salem. Maybe not enough carbon. I've got a couple of cutoffs to try, but the oven's already hot from stainless today.
 
There are a few brand of rasps out there today that are something like 1040..Your customer may have had one of those..Do you you know what brand it was?
 
I was thinking it may have been something like a cheap diamond brand because your heat treat sounds good..You may have to try breaking a piece of cut off after hardening..Try a piece of cut off in brine maybe?
Some newer rasps are just low/med carbon steel that are case hardened..I hope this not your case but it may be..Good luck with it..
 
I have found most currently available rasps are case hardened. They make great wrap hawks with a 1084 bit.....but poor knives usually.
 
I've made a bunch of farrier's rasp knives and try my very best to stick with the old files for reasons stated previously. I heat treat to non-magnetic, hold for 5 minutes, and quench in Brownell's Tough quench heated to about 130 degrees. I have no problems with the blades following a double temper at 375-400 degrees for w hours. I know I am there when I get a nice straw color on the blade. My #1 concern is age...I like the 50 year old stuff or older if I can find it. #2 is brand: Nicholson, Heller, Save Edge...Can't stand Belotta (Brazil)...very inconsistent quality control in their blades.

Here is a super old Stokes I worked up:

hhfilecopperbowie.jpg
 
Well Heller is a premium rasp and all the ones I have used are not case hardened. Case hardened rasp will not cut it for the professional farrier trust me I know. A few years back I called Heller, Simonds, Save-Edge. I was told by all 3 that they basically use 1095.

The best way to check is to take a scrap piece bring it up to temp 1475F hold for 10 minutes and quench in a fast oil. Don't waste anytime getting to your quench. Take your piece of quenched scrap to the anvil and give it a rap with a hammer (Be sure to have safety glasses on) It should shatter like glass. If it is case hardened it will just bend. I have some heller rasps here I used this last week I will do a test with one just to see if these new ones are still holding true.
 
I do the same thing on each rasp as Mike does prior to working it up to a blade....I quench in water though. The ones that bend and don't snap get trashed.
 
1475, 10 second oil, still bends. Guess that's that, not enough carbon. Too bad for the customer who won't get his knives, and too bad for me who already ground and heat treated them :(
 
I do have a question, just wondering if you did some thermocycling on this blade? I would try a water quench on a test piece before you give up. If you need a few good rasps drop me a line I have piles of them.

You could pack carburize or case harden them.
 
As far as thermocycling, I cut the rasp in half to make the blades. I put the blanks in the oven at 1200 for half an hour or so to anneal prior to grinding. I also austentized and quenched twice now, still with no progress.
 
Well that is a bummer, I did not get any shop time to check the heller rasps I just used. I will do it tomorrow and see what happens.
 
Just a thought, but if your rasp has more than 100 points of carbon did you get the blade hot enough before the quench? Before you trash everything bump the temperature up to 1600 F for a minute and quench in water. At this point you can't hurt anything and Heller may have gotten some steel that had a higher carbon content.

Disclaimer: I'm new at this and taking what I've read about the ANSI specs for W1 steel and looking at a phase diagram.

AAaaarg: just noticed the Zombie thread :(

Crackerjack 1945 - Oil speed refers to the @ speed that a blade will cool off when quenched in that oil. Brine is faster than water is faster than oil.
A case hardened rasp will not get very hard in quench. If you forge the rasp by wrapping it around a form then forge weld a piece of 1084 between the edges of the rasp you will end up with a laminated edge on the hawk supported by soft tough steel on the sides and around the part that holds the handle.
 
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