Re: Sprockets & metal casting

[William and Melissa Johns <gizmology-at-gizmology.net>]

Geoff,
   Yes, casting aluminum is a great way to make parts, especially if you 
need lots of identical parts (track links come to mind).  It's dirt cheap, 
too - the charcoal is cheap, and you can even make your own out of 
discarded pallets or whatever.  The furnace (coffee cans) won't last too 
long, but it's even cheaper to replace than the charcoal.  Scrap aluminum 
to melt and cast is everywhere - old BBQ grills are great.  The sand and 
cat litter for the green sand is dirt cheap too.  You might even have a 
natural sand-and-clay deposit in your yard.
   Of course, you can also go bonkers and build a propane or oil-burning 
furnace, buy certified ingot to cast, and buy commercial casting sand, 
which makes the process more expensive.  It's a matter of what you're 
looking to do.
   The catch is that it's a lot of work.  But that's the way it always 
is.  Money or effort, your choice.
   Yes, it is a good way to really hurt yourself.  ("The Center for 
Research on Things You Shouldn't Try At Home", remember?) It's one of those 
things where you're not really too likely to hurt yourself, but if you do 
hurt yourself, you REALLY hurt yourself.  A few simple steps can be taken 
to keep it safer.  Primarily: avoid water!  Hot metal and water can cause a 
steam explosion you wouldn't believe.  If your green sand feels damp, it's 
too wet.  If your flask catches fire, don't hose it off!  Let it burn, or 
bury it in sand.  Don't pour over damp ground (or concrete, which can 
absorb water).  Etc.  Common sense goes a long way.
   The most likely injury is a burn from flying metal from a steam 
explosion.  Wear a face guard, gloves, etc, to cover all skin and you 
should be okay.  Some folks wear spats to protect their feet - I always 
figured you've got to be a real moron to pour metal on your feet, but hey, 
you've got to be a real moron to drop a crucible full of metal, 
too.  (Heh.)  It's cheap insurance.  I use a 2' x 4' shield between me and 
the molds and furnace to protect my feet, heavy gloves on my hands, long 
sleeve quilted shirt, and a clear plastic face guard.  I really ought to do 
something about my legs - jeans don't provide any protection at all!  In 
fact, they  may make it worse, as they could wick the metal up and hold it 
in contact with my legs.  I think I'll get an apron.

   I'm babbling here.  Yes, casting aluminum is an easy, not overly 
dangerous, and dirt cheap way of making custom parts.  Especially lots of 
identical parts.

Bill




At 08:56 AM 12/6/2003 -0800, you wrote:
>Bill, I see on your Web page that you tried casting
>aluminum. I'm wondering how you feel about the
>process. Is it a good way to make custom parts fairly
>inexpesively? Or is it more expesive than you would
>expect, and a good way accidently to burn off
>important body part?
>
>best regards,
>
>Geoff Crimmins

--

"... the slide rule ... most insidious tool ever created and proves the 
devil is among us."  -  The Watchtower