In article ,
Tim Wescott wrote:

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 bought a pile of ordinary firebricks, used to line fireplaces, at the
local brickyard, for something like $1 per brick and no shipping.

When I need to do some hot work, I pile the bricks on top of my wooden
workbench and have at it. The wood does not scorch or even get that
warm.

I use a layer of full bricks on the wood, and half-bricks on top of the
full bricks if I'm making a little forge, usually heated by a big
propane-air torch fed from a 10# picnic bottle.

For quick work with the acyetlene-air plumbers torch, a single
half-brick on the bench works well.

The common 20# picnic bottles are a bit too heavy for portability with a
torch, so I got a half-size bottle for the torch. But I can always
borrow the bottle from the gas grill.

Joe Gwinn