Casting Aluminium would require a seriously expensive electric smelting oven or furnace and has explosion risks (Al spontaneously combusts under certain conditions near its melt point).

Well, speaking from experience, casting aluminum isn't all that difficult or expensive to do. I've used sand-casting techniques in the past to make a few things, and had no problems with the mechanics of it at all. A simple crucible, a small furnace made from a dozen or so firebricks, and a big gas blowtorch allowed me to melt a few kilos at a go no trouble.

My first attempt was making a heater block for a homemade smoke machine, and I melted down a load of old hard drives for the metal. It worked, although my moldmaking skills were decidedly primitive. The end result bore a marked resembalance to a cast aluminum cowsplat.

I'm slowly putting together better facilities to do casting, so I can make some bits for a supercharger. It'll probably be better in the end than machining the part I need from solid, which would require a 10 inch cube of the stuff. I can get it, but god it would take a while.

As far as the risks go, the main one is spilling molten aluminum all over the floor. This is not completely safe.

The explosion risk is more from steam, if either the metal you're putting in the pot is wet (bad) or the mold is damp (very bad). Mind you, when melting scrap aluminum, it's best to make sure it actually is aluminum, not magnesium. That was... exciting.

However, that said, making something as small as the knob or buttons in cast aluminum is a non-trivial task. For an acceptable result, you'd need to do a cast in a ceramic mold, which has to be about 3% oversize in all directions, and centrifuge it to get the detail. The end results of this technique are amazing, but it's not easy.

If you really wanted one-off knobs, they could be cnc-machined, but it would cost. The buttons may be a little small to be economically viable to produce that way.

Incidentally, titanium can be cast in a tungsten mold, but making the mold is the really tricky bit. Tungsten has a seriously high melting point, and what do you cast it in? (hint - it's either sintered or produced by chemical vapour depositation)

Hey, it's just a subject I have an interest in, okay?

Patrick.


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