55 replies to this topic

[Mumbles]

I was thinking of something similar to the corning machine at passfire might work. You could say put on a 100 mesh screen. The bar would crush the chunks of MgAl. You could then screen the resulting powder through a 200 mesh screen. The -100+200 and -200 mesh comprise nearly all the MgAl meshes used in pyro. You may want to try some -30+60 for the sizzling effect.

[Frozentech]

I found this interesting page on grinding metals with a grinding machine. Those machines have similar construction to a ball mill and I suppose it wouldn't be too hard to build one.

http://members.shaw....er/grinder.html

Thanks for that interesting link ! Be careful with this, but it sounds like a great way to eliminate some source problems. If I do try it, I will be certain to follow the advice re: adding dichromate to the water for Mg, and the Boric Acid for the Al. Of course, then comes the potential to slop toxic liquid around the work area. If you get the chance, read Lloyd Sponenburgh's addendum to his latest edition of his excellent book on ball mill construction and usage. In a nutshell he experienced a pyrophoric reaction while using a mill to mix (with no grinding media) 2 micron Mg and Cabosil, which although no flame touched him, took much of the skin off his left arm, and the side of his neck and face just from the UV flash. BE CAUTIOUS.

[Steve]

I thought I'd just have my 2 pence worth.
The first thing that strikes me with this thread is the use of metal milling media, which I consider a very bad idea, you get all sorts of weird reactions going on at a bimetallic surface, due to different ionisation energies, electron affinities and stuff like that. So my first piece of advice is, unless you understand the chemistry, use inert materials, such as ceramic balls a non-metallic jar.

My inexperience of milling aluminium is:
Aluminium - Tesco foil that has been shredded into strips.
Media - 20 mm alumina ceramic balls
Jars - HDPE, 3 Ltr and 15ltr

3ltr jar:
I have used this jar for about six hour mills at a time, mainly with the intention of producing fake powders in the 10-120 mesh range for use in fountains, however there is inevitably some finer powder, which we graded as <400#. This 400 mesh powder was tested in the 70:30 ratio with potassium perchlorate to form an acceptable flash powder. So, if nothing else this shows that flash grade powder can be made in a 3 litre mill jar.

15ltr jar:
This is our big mill jar that Inoxia will be using to manufacture 10-120 mesh aluminium. It eats shredded aluminium foil into a <10# powder in about five minutes. The jar managed to get about six hours milling time before my old and tird mill packed up. It is hard to see what sort of grade the powder is at because it is under the balls and I don't want to empty the jar yet.

The future:
Myself and Andrew have been working on the new mill, and with our new lathe we have turned an indestructible axle. Hopefully the thing should be up and running in a couple of weeks, we plan on doing some much-needed research into the field. I'll add a new post here if we get any new developments. I might stick a photo up of the finished mill.

Almost forgot, we have an electric crosscut shredded now, which kicks arse.

[jerke]

I found this interesting page on grinding metals with a grinding machine. Those machines have similar construction to a ball mill and I suppose it wouldn't be too hard to build one.

http://members.shaw....er/grinder.html

A friend of me, made 2 nice metal grinders i compiled it in a pdf file, if there any questions we could open a new topic i think:

Metal grinding machine

Link: http://www.sendspace.com/file/0z7m2v
File: The Metal Grinding Machine.pdf
Size: 1.71 MB

[mussie_electric]

Being relatively new to ball milling (made my own machine and its great for Willow and KNO3, (not at the same time) I have tried the similar process you describe.. (angled mill container and holes in lid with filter material. Seemed to have no probs with escape of material but reading the posts I have not milled Al foil for long enough.. a week??!! Well I shall go back and try it out for that length of time

[Gavin]

The shredder I use at work has finally packed in so out of necessity I've had to buy a new one. If anyone's interested it's a Fellowes MS-450cs bought from Viking direct. After a bit of haggling I got it for ?99. Pretty boring so far till you find out it cuts into pieces 2mm x 8mm. That'll make short work of ali foil

[BigBang]

Gavin....have you actually put ali foil through it? I have a shredder, albeit a cheapo one, and i tried this, but the damn thing jammed every time i tried to put foil through

[Gavin]

It works a treat. I'll shred up a bit and bring it to KLOB so you can have a look.

[BigBang]

OK mate cheers, see you there (if all goes to plan!)

[starseeker]

I use a blender to shred foil. I crumple sheets of it into fist sized balls before putting it in. It quickly reduces the foil to a sort of twisted, mashed granular form. Be aware that doing this bluntens the blade, so it is helpful if you can remove it to sharpen.

I have also started batches with foil torn into pieces (about 4 or 5cm square). Since the design of the mill and media was very different then, I can't say what difference it made, but I doubt it was too significant.

BTW: I shedded the Al dry - no water, or, as I have also seen referred to, salt. the aim was just to "chop" it, rather than finely grind it.

I have used flint pebbles and large steel nuts to mill aluminium, with effectiveness increasing in that order. There was a silver colour on the jar and media after I milled the Al with it, but I just milled some clay afterwards, before washing it as usual, and this seemed to get rid of most of the colour.

I thought when ballmilling the avoidance of any possible sparks was of utmost importance,so when i read that you have tried flint pebbles Have you ever tried knocking together two pieces of flint fairly hard!sparks are the order of the day!

[fishy1]

I thought when ballmilling the avoidance of any possible sparks was of utmost importance,so when i read that you have tried flint pebbles Have you ever tried knocking together two pieces of flint fairly hard!sparks are the order of the day!

Sparks only really matter when you're milling an explosive comp, that's why it's ok to mill al with steel media even though it sparks. For example, no matter how many sparks you put on charcoal, you won't light it very easy, but one spark on Bp and up it goes.

Edited by fishy1, 21 September 2006 - 08:59 PM.