On Sun, 26 Jul 2009 01:04:17 +0100, Mark Rand wrote:

On Sat, 25 Jul 2009 17:53:55 -0500, Tim Wescott
wrote:


After I bend up my first attempt at a fixture I'll want to do it up
right. It seems like I should just be able to heat up my whole assembly
to a dull red then chuck the thing into a bucket of water -- does this
sound correct? I have some pottery clay lying around so I'll probably
paint the pins with clay & charcoal in an attempt to protect them from
decarburization. When I fish it out of the bucket should I try
tempering it? If so, how, and how much?

The heat-generating tools I have available are pretty much a propane
torch and an O-A cutting torch. The temperature measurement tools I
have are my own somewhat color blind eyes.


Ideally, heat it until a magnet (or magnetized screwdriver etc.) doesn't
stick to it. That ensures that you've got it hot enough to harden. as
soon as possible after quenching, put it in the pre-heated kitchen oven
at about 220C/430F or a bit higher for an hour. If you don't do that,
there is a danger of the pins shattering :-(

Soap, mixed with water to a creamy consistency works quite well to
shield parts form air. It should come off when quenching.

If you can find them, use a couple or four fire bricks or some mineral
wool to contain the heat. Takes a lot less effort to heat parts up with
an approximation to a forge...

So are fire bricks a Home Depot thing? A local welding shop thing? A
"forget about it and get mailorder" thing?

(I want to make a decent forge/furnace that's at least big enough to heat
treat model airplane crankshafts in, and maybe enough to melt aluminum
for a model airplane crankcase, but that's a project for another year).

--
http://www.wescottdesign.com