Grinding aluminum

MM · Feb 1, 1999

I'm going to be making some training knives out of aluminum. What if any considerations are there for grinding aluminum? I'll be using my Craftsman 2"x42" belt grinder. Is there a type of belt that's better to use? What's a good source for aluminum?

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Ciao

MM

Kevin Wilkins · Feb 2, 1999

Alu dust can be explosive. Why not make the training knives out of plastic?

Be sure and wear a good mask and face protection.

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www.wilkins-knives.com

MM · Feb 2, 1999

Explosive? Really!?! I've never heard that. What can be done to prevent it from exploding?

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Ciao

MM

amacks · Feb 2, 1999

Don't use Aluminum. It has two properties that make it VERY bad for grinding. Al dust is very flamable, used as one of the colors in fireworks. The other problem is with thermal expansion. I'm not sure about belts, but if Al gets into a grinding wheel, it tends to either expand more than, or less then the wheel, and could caose the wheel to shatter. (This was told to me by a reputable source, but I've never seen it happen.)
Aaron

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My sheep has seven gall bladders, that makes me King of the Universe!
aaronm@cs.brandeis.edu

Jeff Edmonston · Feb 3, 1999

Two reason for 'explosivity'

1. Most fine powders have explosive potential due to their high surface area be they wheat, sugar, metal, or what have you.

2. Aluminum is readily oxidized. The oxidation releases plenty of energy quickly.

The light produced is white/yellow, when you see shimmering cascading sparks of that color from firework blossoms you are looking at flakes of Al burning

JE

amacks · Feb 4, 1999

A useful/cool studio accident/story. Someone in the studio where I sometimes work was working with Aluminum, old door frames. He had filed some shapes out of one of them on the same table where we use the OAc torch(nice bench vice). I was cutting through a piece of steel, when I notice the surface of the table explode in a shower of sparks.

Apparently the Al and FeO dust had mixed and ignited. This is called a thermite reaction, and produced something on the order on 4000F. Luckily there wasn't much of the stuff, because it cannot be extinguished( the O is broken off of the Fe and bonds to the Al, no outside O is needed.)

Moral of the story: always work in a clean location and VERY careful of Al.
Aaron
ps looks really cool though, build a box of fire bricks, and try a little. Use a strip of Mg as fuse, you don't want to be anywhere nearbye when it lights off, and wear #10 welding goggles.

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My sheep has seven gall bladders, that makes me King of the Universe!
aaronm@cs.brandeis.edu

tom mayo · Feb 4, 1999

yea, use plastic...aluminum is terrible to grind...it melts into your wheel,belt or whatever and clogs it up pronto...it cuts very easily though with proper band saw etc.

MM · Feb 5, 1999

Not to sound like too much of an idiot (hopefully

) but I've seen quite a few aluminum training knives. How were these made? Or probably a better question would be, how could I go about making one. I have several people that want aluminum. When I mention plastic I get a negative response. What about using a mild steel? Would that be better than aluminum. Would it be cost effective. If I did use plastic in what form would I get the plastic?

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Ciao

MM

Ken Cook · Feb 25, 1999

Amacks,
Sounds like it was quite a show! Neat trick, but you only wanna do it once, huh?
MM
Al trainers you have seen in the past werre probably cast to shape.
Actually, you can do this too, but you can use Zinc. Very hard but melts at a much lower temp. Somewhere around 800 degrees, I believe? Anybody know for sure?

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I cut it, and I cut it, and it's STILL too short!

amacks · Feb 26, 1999

I know it sounds odd, but you might want to try using bronze or brass. Both can be worked reletively easily, and neither like to burn. Brass can be bought in many different shapes, but I'm not sure about bronze.
Aaron

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My sheep has seven gall bladders, that makes me King of the Universe!
aaronm@cs.brandeis.edu