NurdRage - 15-4-2011 at 11:10
If i stuck some magnesium turnings in a pepper grinder would i be able to get some magnesium powder out of that? probably not very fine but i'm just
thinking more proof-of-concept.
....or would i destroy the grinding surfaces instead?
Magic Muzzlet - 15-4-2011 at 11:19
...well probably not too many people have even tried this, I sure haven't.
Just give it a go 
I am going to say it won't work, at least not very well and not for long.
Seems like a magnesium block and a file would be better
[Edited on 15-4-2011 by Magic Muzzlet]
mr.crow - 15-4-2011 at 11:31
I doubt Mg would abrade the grinding surface that much since its so light. It might go off in a blinding white flash though
Filing a Mg block is a pain in the ass 
Using the drill press gives a ton of fine
ribbons, but is also kind of a pain and wastes half the block. Maybe grind the ribbons up?
Mumbles - 15-4-2011 at 21:42
Mg as a pure metal is pretty soft. I'd be slightly worried Mg wouldn't fracture cleanly and may just lodge or kind of smear in the mechansim.
Magnesium/aluminum alloy is much more brittle, and could possibly work. I know meat grinders work for some period of time. Even with a coffee
grinder Mg wont become fine enough for pyro purposes, and the small increase in surface area wont do much for chemical reactions.
Fleaker - 16-4-2011 at 08:58
Presuming you have access, what's wrong with using a lathe or a mill and then grinding those turnings up?
I suppose one could ball mill the turnings in argon or in mineral oil (and then rinse it off with hexanes). How active does it need to be?
NurdRage - 16-4-2011 at 10:02
I'm just first curious if it'll even be possible to do, or if the magnesium might
jam/grind/lodge/clog/break/or-otherwise-do-something-weird-and-create-blackholes-that-destroy-humanity.
The "turnings" i have in particular are quite large (>1cm in length). Even getting them down to 1mm would be huge improvement for my chemistry....
for one, they would be easier to get into the apparatus. 
Ultimately, I will be the judge if the end-product is useful or not.
mr.crow - 16-4-2011 at 10:10
Home made Mg powder would be nice. I had a terrible time trying to even buy turnings in Canada.
Hopefully the drill press ribbons work for the Potassium experiment
AndersHoveland - 16-4-2011 at 14:37
Magesium metal is nearly as hard as aluminum (around Mohs 2.5).
However, magnesium-alumnium alloys are very brittle and can be hammered into a fine powder. Interestingly, the alloy can be made by melting the two
metals in a steel can using only a butane torch:
http://www.thegreenman.me.uk/pro/magnalium.html
This alloy powder, known as "magnalium", has several of the advantages over either of its component metals. Magnalium powder is more reactive than
aluminum, while very fine mesh particle sizes are much more resistant to corrosion/degredation from air and moisture than similar mesh size magnesium
powder would be.
[Edited on 16-4-2011 by AndersHoveland]
smuv - 16-4-2011 at 16:04
Well, if this is for chemistry and not pyro, I found that simply grinding my large turnings (like yours 1cm or more) with a mortar and pestle, makes
the magnesium very active. The particle size doesn't change much, but again, it is very active. I think the abrasion removes some of the surface
oxides.
Before this treatment, the magnesium dissolves only very slowly in MeOH (not particularly dry) even with the addition of some ethyl bromide. After
doing this, it dissolves rapidly in the methanol without any additives. If this is for your experiments with potassium, you should certainly try
this.
plante1999 - 16-4-2011 at 16:34
a already make 150mesh magnesium powder for making boron , i use an electric motor with very coars corundum paper on the axe , i made a ramp for the
magnesium round and with a setup that take 1cubic feet i grind about 30g per day.