Is a rasp from the car body fixing – any good?

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Steinmann

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Jan 12, 2010
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I can get an old german rasp from the garage in my area, used to fix automotive body parts and would like to know if it is any good making a knife from it? It does not say what steel it is.
Thanks.
 
Old and German, I'd go for it.
It might be a bit thick for a good slicer and there is always the risk of it not working out.
But IMHO file knives have a certain charm.
There's knife makers that get a hamon in a file knife.
 
I agree. There is a risk of crap steel with unknown files, but it can be reduced by using old stock european or american files. I love making file knives, I look for french, german and english made in particular. You could break a piece off and h.t. it and see what you get.
 
I've read somewere that you can TH the tang and not temper it.
If it brakes off after hitting it with a hammer the file is good to make a knife out of
 
Hengelo_77 said:
I've read somewhere that you can TH the tang and not temper it.
If it brakes off after hitting it with a hammer the file is good to make a knife out of
Click to expand...

I often hear this same thing when people have some mystery steel....."Heat it to non-magnetic and water quench. If it breaks, it is good knife steel."
That is as far from true as anything can be.

Try this - take a piece of 1X1/4" welding steel from the bin at HF. Heat it to bright red, well past non-magnetic, and quench in water. It will snap like glass if you put it in a vise and hit it with a hammer.
This is A36/1018 steel with less than .30% carbon.....which would not make a knife of any quality at all.

There are spark tests, quench and break tests,....I have even read of people who claim they can lick the steel and tell how much carbon is in it. The truth is that all these type of tests will eliminate some things, but tell little about what you actually have.
Unless you have it analyzed, there is only a guess as to what it is in alloy content.
Just being a file or a rasp will not guarantee suitable steel.
Just being a Nicholson or a Simonds file won't guarantee it either ( they have been made in many different places in anything ranging form W1 to case hardened A36)
Age does not guarantee this either, as case hardening was popular 100+ years ago, when good steel was expensive.

Short summation:
Until one has the experience to ascertain a mystery steel as being useful for knives by how it works and hardens, it is FAR BETTER to use a known steel.
Until one has the experience and equipment to work higher alloy steels, it is FAR BETTER to use 1084.
Files and rasps are FAR BETTER for removing wood and metal that they are for making knives.

Old story:
Years back, at an estate sale of a fellow who made knifes, I bought a nice wooden bin filled with about fifty 18" long pieces of shiny 1.25X1/8" steel. The bin was labeled "Knife Steel". It looked like any good stainless steel from Crucible.
I tried to test it by a quick "heat it and dunk it" hardening, and couldn't get it to harden. I figured it was some high alloy that took a long soak to HT, so I sent a piece to the lab. When the results came back, they had run the test twice to make sure it was right. It had .008% carbon ( that is 1/100th the amount of 1084). It also had 15% nickel, and a lot of chrome.....pretty interesting stuff, but it will never make a knife. As to why it was in a box labeled "Knife Steel", we will never know, but as to whether it will make a knife, I absolutely know...it won't.
Moral of the story - get it tested if you want to know what it is.
 
yes, using a file as knife stock can give you poor results, but if you like the look of a file knife then go ahead and just make one. If it doesn't end up with the results you expected then just toss it in the garbage and make another. If you enjoy making them then you wasted nothing. And if you do get one made from good steel they make a VERY good knife. I'm not trying to be contrary here, I actually agree with everything stacy said above, I just feel that you shouldn't be dissuaded from experimenting because of the risk of an undesirable outcome.
 
I agree that a file knife can be a good knife, and has the mystique of the bladesmith craft of yore.

What I was saying is it isn't really a good starter place for inexperienced makers with minimal equipment, and that testing a file won't tell you too much.
 
+1 for bladesmith's advice. I started to say something similar but he seems to say it better... IMHO if you have to ask if it makes a good knife, you probably don't have the skillset to make one from it. Not a slam, I struggle with mystery steel and consider myself at least functionally knowledgeable with my metallurgy. My file/mystery/discovered steel stays in the shop and amongst friends at this point, but I would say I rarely get predictable results. When using mystery steel it is adviseable to have enough of it to destrutively test samples prior to making one particular item. Thus one rasp, one file, small pieces would seem ill advised.
That said, a lot can be learned from working scrap, and I have had a few that turned out really nice and had a unique and impossible to replicate look. I say have at it, but just be prepared to be disappointed.
Bladesmith, think the box of steel was maybe liner material or he was doing laminates? Sounds like highly corrosion resistant stuff... Not to hijack the thread, sorry...
 
Worst case scenario you´ll end up with the best looking letter opener in town.
 
If it is the type of rasp with large curved teeth used for dressing down soldered auto body repairs, and it is still somewhat sharp, it can be very useful for working soft metal, wood and plastic handle/bolster materials. If it is dull and you have spare time...it will be a learning experience.
 
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