[TheForge] Re: slitting chisel / drift

[Grant Marcoux]

Mike:  Automotive coil springs are usually made of 5160 or an analog.
Rarely, automotive leaves and coils are made of air-hardening alloys.  I try
to determine this by cutting "coins" off of the spring.  I will first heat a
length of coil or leaf and heat it to bright orange.  Allow to slow cool in
the forge.  Test with a file, if the piece was air hardening steel, it will
be noticeably hard, even after slow cooling.  Then cut 3 coins and heat them
to low orange, which is about 1500F. Quench one coin in water, one in  oil
and one in still air.  Then check for hardness with a file.

 If the file skates w/o biting, I consider the piece fully hardened. Check
again the air quenched piece, if file bites, it is likely not air hardening.
Check oil hardened coin and if the file skates or barely bites, the alloy is
likely oil hardenable.  The water quenched piece should be harder still, but
I'm reluctant to recommend a water quench, as it more likely will crack.

Ii usually use auto springs in the as-forged condition.  These make
excellent drifts, etc.

Grant
-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net]On Behalf Of Mike Spencer
Sent: Tuesday, January 22, 2008 1:29 PM
To: theforge at mailman.qth.net
Subject: [TheForge] Re: slitting chisel / drift



dave> I have no identifiable tool steel (other than automotive coil
dave> springs) from which to make the slitting chisels and drifts.
dave> Can someone give me the process for hardening & tempering
dave> forging tools made from automotive type coil spring?

There seems to be a lot of variability in springs. So you have to
experiment with one particular spring until you know how it responds
for you purpose(s), then mark that spring "precious" and use it for
the relevant purpose until it's gone.

I, too, live where running down to the store for some H13 (or
whatever) just isn't worth the effort in most cases.

I *do* like the idea of making offset slits on opposite sides of the
bar. (Sorry, I deleted the post and have forgotten who said it.)  I'll
have to give that a try.  My only addition would be that using a slot
punch instead of a chisel will leave a tidier opening.

Somewhere I saw a description of how to make box-joint pliers that
dealt with this problem.  But probably not in qhuite the way you need
for a big railing.

- Mike

--
Michael Spencer                  Nova Scotia, Canada       .~.
                                                           /V\
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^

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