Stanley SW era blade chipping out *LINK*

Coarse Diamond & Hard Steels

Steve Elliott

>Harder steels like the cutting portion of the Stanley laminated blade are often brittle. Coarse diamond stones can cause them to chip. When you increased the angle by 1 degree, that put all the pressure right on the thin cutting edge, causing the chips. When I increase the angle to form a microbevel, I lighten the pressure for the first few strokes until a small flat area has formed at the new angle.

An oilstone or waterstone with a similar grit size will probably not cause chipping.

I've had good luck using very fine diamond as a final honing abrasive on even the most brittle steels. All the chipping problems I'm aware of have been from using the coarser diamond stones.

Bad blade...

Scott Burr in Ben Lomond CA

>Somebody could have overheated it on a grinder or such to destroy the blades temper.

Re: Stanley SW era blade chipping out

Michael R

>It's possible that the blade was hardened but not properly tempered, leaving the cutting edge brittle. I had a carbon steel knife blade shatter to pieces when I dropped it after hardening and before tempering.

You might want to set your oven midway between 425 and 450 degrees and leave the polished blade in there at full heat for half an hour. It needs to come to full heat and stay there for 10 minutes or so. The polished part of the blade should turn to a pale straw color, which is about the right hardness. The rest of the blade should be softer already, and so shouldn't be affected.

You have to have a piece of polished, unheated steel to compare with,in order to seally see the pale straw color come up. If the setting between 425 and 450 doesn't do the trick, raise the temp to 450 and repeat. No need to quench.

AT this point, you won't make it any worse that it already is. Just don't overheat it, and go slow.

MIchael R

I am wondering

Wiley Horne

>if the baking might also help, if the blade is suffering from hydrogen embrittlement from having been left too long in an electrolysis bath sometime in its history.

Wiley

Re: Stanley SW era blade chipping out *LINK*

Ted Shuck, Centennial, CO

>Alan posted this question on The Porch as well and there has been an interesting discussion there. Of special note is a contribution by Ron Hock, suggesting that the blade might have been overheated at some time in the past, leading to a large clumpy grain structure with no toughness.

Leave it to somebody who does this stuff for a living...

I have linked to the thread from the Old Tools Archives.

Ted


The Porch thread on crumbly blade

That is a rare 4C toothing blade

Dan Clermont in Burnaby

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