Hand Tools

Subject:
Re: Edge chipping, again.
Response To:
Re: Edge chipping, again. ()

david weaver
I wouldn't go much above the 340. If it's white 2 or yellow steel (the two most likely in a blade in the lower price ranges), it'll probably be 63 hardness at 340.

Hitachi's tempering charts for white 2 show 217C equating to an ideal (if all other work was done as well as possible) hardness of 60 Rc. that's 32+(9/5)*217 = about 423 degrees F.

I'd not go further than that, and 60 is even a push because it's simple steel and will dull quickly at the sharpness levels you're looking at (as in, sharpness that would be OK in a western tool on harder wood isn't going to be enough for you, so you're operating in a narrower range).

375 and then to back beveling slightly is where I would go next if 340 doesn't work (375 in an oven will definitely result in some spots of the oven being 400 degrees).

The back bevel doesn't need to be large, it just needs to be larger than the length that the chipout is occurring.

In my opinion, if 375 doesn't solve the issue, the issue was present either in the parent steel or in the handling of the steel between manufacture and final temper. As in, nothing you can do about it.

I've tried various things over the years, hammering crappy chisels into knives to see if the hammering would help, and if it does, it's not enough to make them "good".

Tempering information is here:
http://www.hitachi-metals.co.jp/pdf/cat/hy-b10-d.pdf

Page five, item #2 in the table is white 2. Item 5 is yellow 2. I can't read japanese other than a few kanji that show up on stones, but specification of the alloys makes it easy to recognize white 1 and yellow 1.

The next steel down with a 2 beside it is blue 2. Not sure what the stainless steels are as we don't see them in tools. They could be VG10 or something like that - i'm sure they're intended for knives and kitchen equipment.

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