retempering cold chisels

Yes, you have to reharden steel which has lost its temper.

Yup. Although drawing it to blue in the oven (about 450°F) for an hour will have tougher results.

Yep. I'm interested in knowing more about that though...

Tim

-- "I have misplaced my pants." - Homer Simpson | Electronics,

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Tim sez:

"> Yup. Although drawing it to blue in the oven (about 450°F) for an hour will

Maybe not. Tim left out the important step of quenching. Unfortunately, his recommendation only applies if the original steel is tool steel, generally known as O-1 or A-1, describing whether it is "Air hardening" or "Oil hardening". If the steel is high speed steel (HSS) it is impractical to attempt heat-treatment with resources normally available in the home shop. Get a copy of "Tool Steel Simplified" by Frank R. Palmer for proper procedures for both O-1, A-1 and HSS.

Bob Swinney

Actually it only applies to W1. O1 probably will not appreciate a water quench and A1 certainly won't. You'll have to check which alloy it is...

On the other hand, not many cold chisels are made from HSS. Nor does HSS lose its temper at dark red heat. ;-)

Careful with that B.S., Rob! ;^)

Tim

-- "I have misplaced my pants." - Homer Simpson | Electronics,

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Unfortunately,

Tim sez: "> Careful with that B.S., Rob! ;^)

Jeeze, Tim! Sorry. I though we'd agree for once - I read about it in a "Spiderman" comic book.

Rob;^)

Unfortunately,

"Robert Swinney" wrote: Maybe not. Tim left out the important step of quenching.(clip) ^^^^^^^^^^^^ The step of drawing to blue in the oven does not require quenching.

"Leo Lichtman" snipped-for-privacy@worldnet.att.net

Leo

Yes, that's correct. But it's unclear from the original post as to whether the tempering was to be done at the forge/or with torch, or in an oven. And he's talking about spring steel, which is some form of "alloy" steel--5160 or such?--not" tool" steel such as A or O or W steels, certainly not HSS, however.

Frank Morrison

Me too! Id love to see how a chisel will work taking off .04 x .357 slices of hot rolled, 6" long.

Gunner

"A vote for Kerry is a de facto vote for bin Laden." Strider

Snip

When I did my apprenticeship, we were taught to use chisels as you describe. One exercise was to Chisel 2 flats at right angles to each other along a piece of 1.5" round bar. By the time we had finished, we could achieve a remarkable accuracy and finish. Even the scars were beginning to heal.

John

Yeah. Correct. But the original answer from Tim was unclear on this point.

Frank

I will be tempering with torch, as I still have no forge. There is of course the small electrical oven in the kitchen :), and yes the chisels are leaf spring steel. Oh, I just bought another two that seem made from the stems of truck valves (?). BTW, I do have a slab of untreated O1 steel but I dont' feel ready to use it yet.

Regards,

Mongke

Actually I don't recall if car springs (5160) are water or oil quench...

Tim

-- "I have misplaced my pants." - Homer Simpson | Electronics,

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Blue is 560 or more. 450 is pale straw-yellow. Blue will soften the chisel too much.

Dan

For short times yes, but the last time I tempered a blade at 350 it came out almost purple. A bit under, between really dark straw and purple. Just a matter of the oxide being more developed after long hot periods.

Tim

-- "I have misplaced my pants." - Homer Simpson | Electronics,

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