Hot cut Hardie

[gobinu]

G'day all,

Found a nice big chisel at a junk shop yesterday and my plans are to turn it into a hot cut hardie. The edge needs to be completely reworked so I'm going to have to anneal it. My plans are to rework the tool to 30 degree cutting angle. After reading the Hofi stuff about cutting a straight edge with such a beast I think it'll be the most versatile.

My question, what temper should I draw once I harden it back up? Is is necessary to harden a hot cut hardie? This will be my first time at doing any tempering, btw.

[jayco]

gobinu, others may know better than me, but I don't think I would want a cut-off hardy to be really hard. At least not like an axe or wood chisel. Too much risk of breakage and flying shrapnel.
If the stock is a chisel, it's probably pretty good steel as is.

I've made some from axle steel and leaf spring also. I didn't hard-quench those, but left them more or less normalized. They hold their edge pretty well.
They have to be redressed from time to time, but no big deal.

You could always make it and try it in a normalized state.......if it's too soft.........then you can harden it.

Hope this helps!

[S.Willis]

You should not need to temper being you are going to be cutting hot with it. I have never tempered any hot tools. The temper would eventually draw back out any way by being in contact with the hot metal.

[ThomasPowers]

Well the temper temperature of some hot work alloys is in the glowing range---you shouldn't be exceeding that in use!

I'd go with normalizing as a first guess too.

[gobinu]

Yea, a little after I posted I realized that normalized made sense. Sometimes these forums are a little too convenient and circumvent thought. Of course, I was also reading a blacksmith book when I came to that conclusion. So it probably was in there somewhere and popped into my head.

Thank you all, and I'll let you know how it turns out.

[S.Willis]

Thats correct on the hot work alloys. Being made from a chisel from a junk shop it probably safe to assume it is not hot work alloy

[civilwarblacksmith]

When you go to use the cut off hardy, I would use a brass hammer just to be sure the hardy doesn't break.

[ThomasPowers]

I pick up old stone/cold chisels at the fleamarket for knifemaking and you really don't know what you are getting---I've had some air harden in a knife thick section---makes it rather difficult to file until you go back and do a full anneal on it. Others you have to really work at it to harden up like you want it for a blade.