[TheForge] slitting chisel / drift

[Mike Linn]

1. Typically I forge to shape, then bring to critical 2 or 3 times then 
harden in transmission fluid. I normally do a 1 step harden/temper where 
I quench the working end and leave heat in the striking end, then let 
the heat run into the quench while filing so I can feel the hardness. 
Just when the file starts to cut I quench the whole thing.  In this 
circumstance you will probably need 3 or 4 cutting /slitters and a 
minimum of 2 drifts. Otherwise you will be rehardening every few heats. 
With that much to do I would look for a source of H-13 or another air 
hardening steel.

2. Typically this is done in some kind of form/holding fixture. Ive seen 
it done on angled bar but all of the holes were done at the same angle 
so the fixture worked well. In this case almost every hole will be a a 
different angle. The only way I can think of to do it is to make some 
sort of domed anvil with a hole in it to allow the punch and drift to 
pass through.. its a toughie and you'll probably need 2 helpers to hold 
the piece.

mike


Dave Mudge wrote:
> Friends, I need a little advice on two issues.
> 1. Although my new shop is not up and running yet I have a temporary
> set-up in the machine shop where I work.
> Air hammer, gas forge, anvil, swage blocks etc.
> We have a job coming up where I will need to slit & drift 1/2" square
> holes in 3/4" x 1-1/2" flat bar on 6" centers.
> I have no identifiable tool steel (other than automotive coil springs)
> from which to make the slitting chisels and drifts.
> Can someone give me the process for hardening & tempering forging
> tools made from automotive type coil spring?
>
> 2. This is a railing. Imagine the afore mentioned 3/4" x 1-1/2" flat
> bar as a wave running the length of a section of railing.
> The 1/2" square pickets will pierce the wave on 6" centers.
> The holes to be slit & drifted to size will have to be on an angle
> that would be on tangent with the straight pickets and the
> curves of the wave. Piercing the bar on the flat would be one thing,
> but piercing it on an angle is quite another.
> Any advice on how to do this would be appreciated.
> thanks,
> dave mudge
> Bogalusa, Louisiana
> dave at magichammer.net
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-- 
Mike Linn
Artisan Blacksmith
McCalla, AL