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how hard would you make a stone-chisle??


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may be an odd question... i know ;) tomorrow I will reveal the results .... your not-so-usual stone-chisle B)

 

however... I wanted to ask if anyone here got a good idea about how hard (HRC) a stone-chisles "cutting-edge" should approx. be?

 

 

thanks

 

Daniel

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Daniel, don't know if it makes much difference what kind of stone you use, but one of my teachers was a marble carver and he suggested the end be something like purple to blue at the tip and a little less drawn further back.... Might be just how he did it, but there it is....

 

I keep meaning to make some of my own carving chisels but can't seem to get to into it considering I can't afford to by the marble to work.... lol Too bad, I am not a bad sculptor sometimes.... But, money is an object and obstacle if you don't have it.... heh, heh....

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thanks.

 

I used to repair and reforge a lot of construction-site tools..... mostly reforging deformed / dull tips and reheat-treating them.

 

I after the reforging and a quick grind I heated them to non-magnetic and quenched only the tip in water (but quickly...) pulled it out ... used a rasp to remove the oxide and waited 'till the tip got blue and then into the oil...

 

this was the procedure I was told to do with that sort of tools... but I had not much info about the steels... so not much idea what Hardness a 290°C temper will result in.

 

anyways... with this piece (intended for "soft" stones, like marble, sandstone, limestone...) I'll go for a blue temper... resulting in approx. 58HRC I guess t hat should work fine.

(it's 01 steel... I know... not the perfect choice for the the job, but goes well with the damascus rest ;) )

 

thanks again.

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On an old book i read that stone chisels were tempered to bronze color, so pretty hard. There was written that you have to harden not only the edge, but also the area that you hit with the hammer.

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The harder the chisels are the longer they will stay sharp. The best stonecarving chisels are made with carbide tips, brazed on, instead of hardened steel. Of course the harder they are the easier to shatter so usually just the teeth of the chisel are hardened, 3 to 4mm. Chisels for harder stones usually are drawn to a straw or bronze color and are ground with a larger angle on the tip (duller). Chisels for softer stones would be ground to a smaller angle (sharper) and tempered back to a purple or blue depending on the stone they are intended for. Hammers used by stonemasons to strike chisels are, often, made of unhardened steel. Hardening the end of the chisel that is struck makes it so that when struck by an unhardened hammer it "bites" and does not slip off the end of the chisel. Sometimes chisels would be cupped slightly on the striking end and hardened to provide even more "bite". Traditional steels for stonemasons chisels have 100 to 130 points of carbon and that's about it. There are a few businesses in Italy that still make stonecarving chisels the "old way", might be worth a roadtrip to check them out.

Edited by B. Norris
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Well, you need to know how hard it is BEFORE you temper it. If we quenched out a .95%C steel and a .15% C steel, and tempered them both at 300F, which one do you think would be the hardest? The tempering temperature would drop them both approximately the same number of Rockwell units (assuming we have no significant alloying differences) but I am betting the .95C would be a lot harder even if it were the same temper color as the .15C steel.

 

I would guess stone working tools would be in the Rc 40-50 range.

Edited by RKNichols
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