Used chisels arrive with heat colors. How much to remove?

[Clark Magnuson]

If there are colors like this, does it mean the tip has lost is temper and I should grind that part off?

I have a wet wheel delta grinder and a couple other grinders.

TIA

[Mike Henderson]

It looks like someone overheated the chisels but what I'd do is sharpen them and see how they perform before I started grinding a lot of metal away.

Mike

[Patrick Chase]

If there are colors like this, does it mean the tip has lost is temper and I should grind that part off?

I have a wet wheel delta grinder and a couple other grinders.

TIA

That dull blue-gray color on the top one is very bad news as that indicates that it was heated to >750F (depending on the steel). Assuming it's O1 or similar that corresponds to something like Rc52 in the best case. While we've already established today that hardness isn't the only thing that matters in a chisel, that's really really low. I wouldn't even bother trying the top chisel - just grind the discolored part off.

The bottom one is more of a borderline case. That color corresponds to 570F or so, which would be ~Rc57 in O1. If it were my chisel I would grind it off, but if you sharpened it up you might be fairly happy with it.

[ken hatch]

Maybe I'm nor seeing what I think I see but....I'd be a lot more worried about the pitting than the color. Loss of temper can be ground past, pitting is forever.

ken

[Clark Magnuson]

362863

I changed the edge angle to be twice as shallow and got rid of the bevel on the back side.

I was tolerating just blue color.

These two cost $5 each delivered.
I thought the Witherby brand was good after reading this:
http://www.sawmillcreek.org/showthread.php?13734-Wood-Chisel-Survey-for-Beginners-(Revised-For-The-Record)
7 years ago I found a Greenlee socket chisel in the garbage, fixed it up and was surprised how good it was. That lead me to sawmillcreek.

But these two Witherby Woodchuck chisels do not seem to be high quality at all.

The are very sharp after bench grinder, 300 grit diamond, 1000 grit diamond, then the strop with rouge. But I don't know how long they will stay sharp, and have not some up with a controlled test.

[Nicholas Lawrence]

Witherby is a good brand, but those do not look like they have been treated very well by their prior owners.

[Mike Henderson]

Witherby is a good brand, but those do not look like they have been treated very well by their prior owners.

He mentioned Witherby "Woodchuck" as the brand. All the Witherby chisels I have are marked T. H. Witherby. I never heard of Witherby Woodchuck.

Mike

[Nicholas Lawrence]

You are right. I missed that in the initial post. I just made out Witherby in the photos. Disregard all.

[george wilson]

Ground on bench grinders and burned by those weekend home repair persons I referred to in the Irwin post,page 5 Pitted from being in the bucket in the damp basement.