Ball milling with a stone tumbler.

[xoo1246]

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<small>[ December 28, 2002, 12:14 PM: Message edited by: xoo1246 ]</small>

[Polverone]

I have a small rock tumbler and an improvised ball mill made from an electric ice cream maker. The rock tumbler actually already has indentations/ridges on the inside to make things get carried up and drop, so I never had the problem you've encountered. The milling media you use makes a world of difference. I use soft lead balls for making BP, and they do an excellent job of reducing materials to fine powder, even in a container without ridges. I use marbles for milling stuff that I want powdered but not contaminated with lead. The marbles take probably 4-5 times as long as the lead balls to accomplish similar grinding tasks. I would like to try brass or hardened lead balls but I haven't been able to find any, and they'd probably still contaminate the chemicals somewhat.

[THErAPIST]

i came across my old rock tumbler in the shed th eother day. i was gonna throw it away but i figured i might use it again (for its real purpose) some day so i kept it. the thought of turning it into a ball mill came across my mind for about 3 seconds and then i figured that it wouldnt work so i mentally killed that idea. maybe i shall go have another look at it and see what i can come up with. good idea

[EP]

I've been looking into rock tumblers recently also. I seem to remember hearing that hexagonal chambers are becoming more common now, but I think cylindrical would still be fine.

United Nuclear sells Lortone rock tumblers as ball mills here:

<a href="http://www.unitednuclear.com/mills.htm" target="_blank">http://www.unitednuclear.com/mills.htm</a>

They also sell hardend lead balls for milling, which will probably help a lot for good milling. The prices on the rock tumblers/ball mills and UN suck, so looking at the Lortone website I found them listed much cheaper:

<a href="http://www.lortone.com/tumblers.html" target="_blank">http://www.lortone.com/tumblers.html</a>

I also saw some decent prices on eBay (search "rock tumbler" or "lortone")

I'm thinking I'll just buy one of these (probably the model 45C) because I'm not all that good at making these kinds of things. Has anybody used this brand or could anybody ask on rec.pyrotechnics? (I still haven't figured out how to post there :rolleyes: )

edit: spelling

<small>[ September 20, 2002, 08:45 PM: Message edited by: EP ]</small>

[megalomania]

I have been thinking about making one of these lately to reduce some things to powder (not pyrotechnic materials). I wonder if I could employ a window fan to do the job? I have an older one that is starting to act up and I fancy that I can adjust the high/medium/low knob to slow it down a bit. I did an internet search for improvised rock tumblers and all I came up with were a few giant truck tire sized ones, all the rest wanted money for their plans.
I got a new Small Parts Company catalog a while ago and they sell a varity of metal balls for not too much. Are there sources out there of steel balls? I used to have a bunch in my marble collection when I was young, but I have no idea where they came from. I think $7 is a bit steep for 25 half inchers, but what can I do?
I have some instructions for an improvised eluter to seperate different grades of grit for rock tumblers if anyone is interested.

[xoo1246]

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<small>[ December 28, 2002, 12:14 PM: Message edited by: xoo1246 ]</small>

[Fl4PP4W0k]

This may seem pretty obvious... but a great source for large (3\4"+) soft lead balls are off-shore fishing tackle stores. These are great when combined with a handful of half inch sinkers.

For steel balls, you may be able to find some muzzle loader ammo? I know the larger balls are .58 and .62, and I've seen steel ones around on some website. Ill check.

(I live in Australia, where muzzleloaders are... for some fucked up reason, illegal. I cant really picture someone going on a murderous rampage with a musket... but hey :D
Therefore... I havent actually seen large calibre steel ball in person... but on hunting sites etc...)

l8r

[xoo1246]

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<small>[ December 28, 2002, 12:14 PM: Message edited by: xoo1246 ]</small>

[megalomania]

Ahh, yes, I have seen large caliber brass balls at Wal Mart sold in packs of 9 or so.

[xoo1246]

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<small>[ December 28, 2002, 12:18 PM: Message edited by: xoo1246 ]</small>

[xoo1246]

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<small>[ December 28, 2002, 12:13 PM: Message edited by: xoo1246 ]</small>

[CyclonitePyro]

I use a Lortone 3A rock tumbler,l it has a rubber barrel. I use 1/2" steel ball bearings. I've milled many materials, black powder, naphthalene, KClO4, and things I can't remember, without any problems, the fineshed product is always very fine.

[xyz]

A bit off topic but I don't really want to start a new one.

I have been trying to make a ball mill for a while, I am using a large 240v motor from a vacuum cleaner and it spins extremely fast, all atempts at using a belt to gear down the motor have failed because the belts tend to come off or snap. I had the idea that I could attach the milling jar directly to the motor shaft (normally you could'nt do this because it would spin way too fast) and then use a light dimmer switch to turn down the power untill the jar turned at 150rpm or so.

Also, I have been thinking about using lead sinkers for media but they have a hole through the middle and I think that the hole would get packed with whatever you were milling and this could have bad consequences if you milled something else without cleaning them thoroughly first. Any suggestions on fixing this?

[None]

You could just fill them with solder or rinse them in water after every use.

[Mick]

just get a pair of pliers and "moosh"(technical term) the holes over.

its only led, its soft as shit.

i can't see why you couldn't use a dimmer switch to turn down the motor. i still don't think you'll get it to spin slow enough, but with a dimmer/belt combo it would work.

[BrAiNFeVeR]

A simpe dimmer won't work, because it only has a resistor in that, and the rpm of an alternating current motor depends on the frequency of that current.

The only thing it will do is lower the power of the motor (wich may slow it down) but it won't do this very good.

I suggest you try to find a DC motor (like from a battery operated drill), they have motors that are easily adapted to suit your needs ...

[Zach]

hi folks, ive been away for a while due to things hitting the fan.
anyway, does anyone have an idea how lead balls are "hardened"?
I am lucky to have access ball end mills ( not ball mills. ball end mills are milling cutters (sort of like a drillbit) that are rounded on the end to create a perfect half-sphere hole) and a milling machine, so i have fabricated several ball molds. I have acheived seemingly good success with mixing molten lead and zinc to be poured, lending a harder ball. Zinc is, however, fairly reactive, and I'm not sure i want to mix zinc with chemicals/drugs ect. ect. ect.
Possibly a denser lead ball can be obtained by running them alone in a steel milling container... or glass, if one can avoid breaking it.

[Marvin]

BrAiNFeVeR is very neerly right about the dimmers. The variable resistor controls a triac circuit, the setting on the resistor controls the firing delay at each point in the AC waveform. The result is an AC waveform with the front cut off and its only capable of driving resistive loads. Try driving an inductive load and it wont work, apart from burning it out. Power regulators and DC motors dont work well either, by the time youve reduced the speed to what you want the motor has bugger all torque. The only thing that seems to work half decently in this vane is induction motors (the kind with a only single winding around a metal horseshoe and a metal rotor, being regulated with a variac, which is a variable transformer.

Try buying a small box of mechanno, useful for small cog driven problems. Alternativly 2 wheels made of 3 disks of wood with the middle smaller makes a pully the belt/band cant come off.

Lead can be hardened by adding antimony to it.

My ball mill is an unmodified tumbler half full (around 100, and its small) of marbles. If its overfull of powder it wont grind well, if the powder is damp it sticks to the side and I get the same problem. Takes about 24hours to turn a ground mixture into a very fine powder. I havnt been using it long, I'll run some tests to find out how fine it will go. Speaking of which, anyone know a cheep place to order sieves for seperating grades of powder? The places Ive found so far are extortionate.

[Anthony]

I used lead as-is and didn't have problems with the hardness of the media, but I guess if you're milling metals then it might.

If you want to harden your media with antimony, but can't get it, you can cast your media from melted down airgun pellets. They contain varying amounts of antimony. I suspect that bullets will be the same, and you'll need fewer.

Tip: for motor drive, go to a big chainstore DIY/hardware place and pick up their special offer cordless drill - usally 9.6 or 12v for about £10. The motor will come out as a unit attached to a reduction gearbox and the chuck. Use the chuck to drive the spinder of the driven roller that turns your milling jar. Cheap cordless drills usually run about 600rpm, so to get a jar speed of 150rpm, make the driven roller one quarter the circumference of your milling jar.

The motor doesn't draw much power and will run indefinitely without overheating, although I've never driven a real heavy jar with one, so this might not always be true, especially if your bearings aren't up to much.

The cheapest way to supply the motor with DC is a car battery charger. Don't worry about using a 12v charger if your drill was only 9.6v - they all use the same motor anyway for cheap drills.

Since I like using everything for something, use the nicd battery pack from the drill for your electric blasting machine, and the charger to recharge it.

Note, you could use the speed controller in the drill (if it has one!) to vary the motor and this jar speed, but I don't know how well they'd do in continuous duty as they're usually damn cheap and the first thing to go up in smoke if you use the drill hard.

[EventHorizon]

<a href="http://www.mcmaster.com" target="_blank">www.mcmaster.com</a> should have a large variety of milling balls. That Small Parts Incorporated catalog had a lot of nice things in it, but was very expensive. I would think that some 1/2" or 5/8" tungsten carbide balls would work very well.

EDIT:

Tungsten carbide is rather expensive. :( (well duh, right?) However 1/2" brass balls are $14.12 for 25. Much cheaper than the TC ones at $10.08 each. 8-O

EDIT 2:

Doing some additional checking they also have stainless steel balls. 316 or 440C would probably be the best ones to get and they are $8.95 for 10 316 SS and $12.27 for 25 440C, both 1/2".

<small>[ September 29, 2002, 09:46 PM: Message edited by: EventHorizon ]</small>

[Positive Electron]

you guys ever hit a hammer against a nail kinda crooked? notice all those sparks flying off of it? now think about what a hammer and anils are made of, steel. steel sparks, and milling with steel is not a good idea. i'm not sure about brass, but I think it my spark too. try using hardened antimony lead, no sparks and as hard as steel :)

much safer when milling black powder too :)

[Anthony]

Well you have a point, you can be over zealous with safety.

If media in a mill struck as hard as is required to strike a nail with a hammer and produce sparks, BP wouldn't take 6-12 hours to produce...

Basically, everything except steel/iron is considered safe. But I'd hazzard a guesstimate that it's be more specific to say all non-ferrous metals?

Anyway, lead is considered safe, but lead on steel *does* spark.

[Positive Electron]

being overly safe when milling blackpowder is absolutely necissiary because even if your media only sparks 1:1000000 times, that one time your going to end up with a bunch of steel balls flying everywhere.

edit: made a mistake

<small>[ October 04, 2002, 03:21 PM: Message edited by: Positive Electron ]</small>

[pyro225]

Antimony hardened lead was mentioned in this post as good material for grinding media. According to ball milling and pyrotechnic guru "L.E.S." (see "The Best of AFN IV" pages 164-170, Ball Milling- Some Science in a Black Art), this material is "heavy and hard enough for most pyrotechnic purposes, but high density ceramic media are easier to clean, and grind somewhat finer." There is, however, a possibility that ceramic may spark, and it is definitely more expensive and inaccessible. It is commonly recommended at the rec.pyro newsgroup to use melting wheel balance weights to cast lead grinding media. They already have the necessary antimony added as a hardener - they just need to be "recycled". If you have a friend at a tire store, have him collect a bucket of the used ones for you. Or offer to remove the used lead from the premise at no charge, under the premise of making fishing weights or muzzle-loader balls. According to a chart for media charging rates in the above mentioned article, you will need 29 lbs of lead balls per gallon to optimally charge your milling jar. With a specific gravity of 11.35, that's not really that many wheel weights. I have successfully used a Lortone rock tumbler for small 2-4 oz batches of pyrotechnic compositions. I used .50 caliber NON hardened lead balls and it seemed to work, though it took quite a few hours. There was some evidence of lead "contaminating" some of my comps, probably due to lack of hardener. I think one of the disadvantages of a rock tumbler is the rubber jar(at least in my case) - not hard enough of a surface to pummel your material well. I will soon replace it with a 3-4" PVC jar (which will fit nicely on Lortone's roller assembly) and cast some 1/2-3/4" hardened lead balls for media. This will increase my batch capacity and improve my efficiency. I have only a small bit of experience with ball milling, and I've gleaned all of what I know from the above article. There is also a 66 page book by the same author which covers in greater detail all aspects of ball milling, including building your own mill. This book is generally regarded as THE manual on ball milling for amateur pyrotechnics. Hope this helps.

[Anthony]

Positive Electron, I presume that you run your mill in a hard rubber jar, with platinum media, FULLY grounded, and anti-static treated? With explosion proof rated motor, electrics, bearings, gearing, RCD protection, in a specially constructed strong walled, weak roofed building, with multiples layers of blast walls surrounded, with nothing but open land in a 10 mile radius and full remote manipulation of the mill?

Whilst I'm not saying you should ensure your safety, there will *always* be some chance of you being inured/killed, so it's a compromise between the extent of your precautions and practicality.

Pyro225 is that book you mentioned "Ball Milling Theory and Practice for the Amateur Pyrotechnician" by Lloyd Sponenburgh?

[pyro225]

Anthony wrote: "Pyro225 is that book you mentioned "Ball Milling Theory and Practice for the Amateur Pyrotechnician" by Lloyd Sponenburgh?"

Yes sir, that would be "The One". If you're looking for it, it's available from several of the online/mail order pyrotechnics suppliers. I have only the 6 page article in "The Best of AFN III", which is I believe excerpted from the book.

EDIT: Sorry to be vague about the author and book in my original post. I wasn't sure how the author would view the subject matter with which this forum deals. Now that I think about it, his book is a primer on ball milling, so the application of his techniques is not really his issue.

<small>[ October 06, 2002, 11:12 PM: Message edited by: pyro225 ]</small>

[kingspaz]

pyro225, whether he cares or not whats the chance hes actually here? and if he is here hes here for the same reason as us and so wouldn't give a dam :)
i think that book might be a good idea for the ftp if anyone has the full version.

[webmaster]

You can use a blender. You can get steel balls from slingshot ammo. Also if you are looking for plans on making a home mill here is a good site to look at <a href="http://huizen.dds.nl/~wfvisser/indexEN.html" target="_blank">http://huizen.dds.nl/~wfvisser/indexEN.html</a>

[Tuatara]

I've found a good option for a milling jar for a homemade ball mill - the bottle of a 2 litre garden pressure sprayer! I found this at a discount plasticware shop (NZer's will know about 'Payless Plastics) for NZ$10. Its made of 5mm thick HDPE, has parallel sides, rounded ends, 50mm neck (easily plugged with a rubber or cork bung), and is about 12cm diameter . I put in 3 lifting bars made of 10mm wooden dowel, by simply drilling holes each end of the bottle and inserting the dowels.
Pressure sprayers also come in 5 and 6 litre versions, if you want a bigger jar.
The only downside is that it is virtually impossible to glue anything to HDPE, should you need to.

I ran the mill for the first time yesterday - turned inch size chunks of charcoal into fine dust in about 3hours. Milling media: 6kg of 50g lead balls, made the day before (that only took 2 hours) using a fishing sinker mold.

[Mick]

the ball mill i made/used a while back, mainly for grinding up AN, was an old clothes dryer.(tumble dryer?..we call it a clothes dryer in OZ, dunno about everyone else tho)

best idea EVER as far as i'm concerned.
i can mill up 10kgs of AN(could prolly do 15kg if i wanted..could do even more if i extended the drum slightly) in around 5 hours.
the media i use is a 10kg roll of lead roof flashing(kind of like a rolling pin), plus a handful of lead balls, marbles, sometimes i'll throw some brass tap fittings in as well to "spice it up a bit"(altho, i notice absolutely no difference in the final product)


i had to convert the drive train of the dryer to use a chain rather then a belt because of the weight - with the belt it wouldn't spin the drum when you turned it on, and it would periodicaly stop, burning out the belt. i added some extra support rollers to the outside of the drum cause the dryer is only designed for 5kg max - not 30kg. i also had to plug up the "air holes" in the back wall of the drum too using a welder and some thin sheet metal.
its also good for mixing up ANFO too. i just put the FO in a small spray bottle and as the AN goes round and round i spray it.


something i have been thinking about is milling up some KNO3 for some rocket fuel, but due to my hiatus for the past year i've forgoten just about everything i used to know(which wasn't much mind you)
whats the danger with milling KNO3..i'm sure there was somekind of static danger or something?(or maybe its AN that has the static danger, and KNO3 is safe...hmm)

[Sparky]

If you're milling potassium nitrate by itself then you have nothing to worry about.

My friend's ball mill was made for free from an old duct fan. These are the fans used in ventilation for big buildings. They come with:

A big steel drive bar
2 bearings. These are what I think what people call bushings. Basically brass tubes that the steel rod fits into, then put grease in to lubricate.
A large and small pully, and a belt.
A 1/2 horse power motor and a mounting bracket to hold it with. The bigger ones have 3/4 horse motors.

The place next to his house used to throw these out every once in a while. Though I noticed they have stopped. Maybe they weren't really throwing them out, just storing them next to the dumpster :rolleyes: . Anyways he got enough for his friends too, and another one to make a star roller :cool: . All you need is bearing to hold the other side of the jar up. Castors like those used on the bottom of chairs would work, though he uses a ball bearing from a bike wheel. Currently he uses a peanut butter jar with marbles in it to mill with, though the motor could handle way more load. The problem with having a screw on lid is that if you put the jar in backwards it opens up by itself :eek: .

Here is a diagram of the ball mill: http://pyropage.cyberarmy.ca/BallMill.gif

Gearing down the motor for a ball mill should be pretty easy as long as the drive bar and shank coming out of the motor are standard diameter. Even medium sized hardware stores carry any pulleys and belts you would need.

[jeffchem2000]

Lead can also be hardened with tin. solder is a tin lead alloy ranging from 40-60% tin.

When I was making my ball mill, For the ball bearings I was cutting a steel rod into chunks and my dad suggested that I build a rod mill as opposed to a ball mill. Me being lazy thought it was quiker and easier so it was worth a try. The results from the rod mill were really good I have used it to crush charcoal and also sulphur. The powders produced were really fine after only a few hours (I didn't check how long)

[Tuatara]

Tin to harden lead? Surely only in very small proportions, not like solder, which is extremely soft!

[nbk2000]

Tin is used to lower the melting point of lead for use as solder.

Antimony is used for hardening lead for use in bullets.

Don't confuse the two.

[Bert]

Get an old washing machine motor. It's designed to start under heavy load and work continuously with the kind of load a drum full of heavy milling media represents.

Stainless steel is a good choice for single component grinding. Try a 310 series.

Here's a cut and paste of one of the best milling posts I've seen. Myke, the guy who wrote this does this for a living-

NBK2000, this is the format it was in. Don't get too upset with me for leaving it as I got it.

================================================== ===

1. Mill ignitions, there are fifteen distinct causes:

A. Static electricity internal - charge build-up from load.
B. Static electricity external - mill drum, belt & rollers.
C. Piezoelectricity - charge build-up due to media impacts.
D. Pyrophoric media - impact sparks - spark sensitive load.
E. Triboelectricity - load friction - spark sensitive load.
F. Redox interaction - incompatible mill medium for a load.
G. Sensitising medium - a non-obvious ignition sensitivity.
H. Exothermic drying - safety solvent loss milling a metal.
I. Pyrophoric load - ignites on opening mill after milling.
J. Heating due to excess input power - bad mill parameters.
K. Friction ignition - bad load and/or bad mill parameters.
L. Impact ignition - inappropriate mill medium and/or load.
M. External source, mechanical - mill bearings overheating.
N. External source, electrical - motor brushes/switch arcs.
O. Physical failure of the operating mill causing ignition.

2. Materials for media/mill, there are twelve basic classes:

A. Ceramic: aluminium oxide, silicon dioxide, silicates and
other less common ingredients, like titanium dioxide. It
should be noted that flint is SiO2 - metamorphosed jelly
fish sediment found in carbonate deposits. Thus, it is a
fact that silica based ceramics produce striker sparks.

B. Glass: hard borosilicate, soft soda types and soft/heavy
lead crystal, etc. Since many glasses contain silica, it
is reasonable to expect striker sparks. Glass is a fluid
but ceramics are solid microcrystallines and/or sintered
amorphous materials with distinct properties, like being
piezoelectric or ferroelectric.

C. Copper and alloys: brasses (Zn), bronzes (Sn) and monels
(Ni). Alloys of copper sensitise a chlorate, perchlorate
and nitrate mix. Particularly dangerous is the formation
in-situ of copper amine compounds from milling compounds
that contain NH4, especially ammonium perchlorate.

D. Lead and its alloys, using: antimony, bismuth or calcium
as hardeners. The production of pyrophoric lead dust has
caused many mill explosions: typically while the load is
still warm and being emptied into fresh air. In commerce
of old, the load was allowed to cool then emptied into a
deep wood box filled with carbon dioxide gas.

E. Non-ferrous light: aluminium, and its non-copper alloys.

F. Ferrous: iron and its addition alloys, like a mild steel
or a tool steel (both easily produce sparks) do not have
a role in impact pyrotechnic milling. Non-impact milling
can use iron based wheels, as for a vertical heavy wheel
mill, like traditionally used for blackpowder, but it is
an economic/practical choice intended for remote running
and control with appropriate safe distances, etc.

G. Low-ferrous heavy: 310s24 Cr 25.0%, Ni 20.0%, C 0.12%.
317s12 Cr 18.0%, Ni 15.0%, Mo 3.5%.
316s16 Cr 17.8%, Ni 10.0%, Mo 2.8%.

These stainless steels are the preferred general milling
media for pyrotechnics. Typically used with rounded ends
in mixed lengths and diameters. They are non-sparking.

H. Special compounds: tungsten carbide, boron carbide, both
very hard; the former heavy, the latter light. Vitallium
high temperature cobalt/chrome alloy is used for milling
ceramic powders at high temperatures, very expensive.

I. Hard and soft rubbers: silicone and butadiene based used
for the incorporation of special explosive mixtures.

J. Plastics pure: Teflon, UHMW polyethylene, melamine, etc.
K. Plastics filled: as above + stainless steels, lead, etc.
L. Hardwoods, typically: ebony, ironbark, mallee root, etc.

3. Mill types, there are eleven basic types:

A. Horizontal tumbler - various types: plastic, glass, wood
and hard rubber. Used with various media. Most common in
small scale pyrotechnic milling operations. A metal mill
tumbler should never be used for pyrotechnic composition
milling - but they are used to prepare materials such as
charcoal. Steel tumblers find wide used in lapidary with
slurried polishing loads. A large conical type is useful
in milling common minerals and ores.

B. Horizontal heavy wheel - classical mill-stone types used
for milling cereal grains, etc. Usually a bed stone with
a rotating top stone, both typically granite - a central
feed hole with continuous peripheral delivery.

C. Horizontal heavy rollers - classical crushing mill for a
wide range of rocks and ores. Typically used as a coarse
sizing mill - with or without toothed rollers.

D. Vertical Stamp - classical rise and drop hammers working
in a sloped or horizontal trough with or without running
water as a milling aid. Used to mill ores, etc. Used for
making bright aluminium flake - with oxidation inhibitor
like paraffin wax.

E. Vertical heavy wheel - classical single or double wheels
running around in a pan. Widely used in a remote milling
operation for incorporating blackpowder.

F. Edge-runner - a trough mill with reciprocating blades to
size and blend mixes with a dough-like consistency, like
some propellants.

G. Rotating trough vertical - like a car tyre rotating with
one heavy rolling ball inside it. Often used for packing
flaked clays, which are tapped free from the inside with
a mallet. Often improvised by hobby potters using a tyre
and hanging belt drive.

H. Rotating trough horizontal - like a circular edge-runner
mill using a sequence of staggered mulling disks running
freely in the rotating trough.

I. Tilting trough - see-saw action with one rolling ball. A
version of the edge-runner mill, but employs gravity for
driving the rolling ball. Typically used to grind slurry
mixes that slowly flow through with the tilting action.

J. Tilting circular pan - cyclic/angled rotation that works
with gravity to drive a square edged ring around the pan
against the pan's inside wall. Generates combined action
of flat grinding with rolling incorporation to produce a
very uniform particle size and shape. Especially used to
produce fine rouge polishing slurries.

K. Mortar and pestle - an automated version of usual mortar
and pestle. The mortar rotates slowly as the pestle goes
over and back across the open mortar. The pestle must be
matched to the curvature of the mortar. Once used by the
early makers of fine artist oil colours, where very long
milling times and a gentle action produce consistency of
hue and texture from natural pigments, resins and oils.

There are various implementations for all these mills, which
as patent attorneys would say, are obvious to anyone skilled
in the art of milling. Given the above possibilities finding
a mill/media/load combination to suit a given task should be
easier. My first choice for general pyrotechnic milling is a
tumbler made from anti-static HDPE, a 310s24 stainless steel
milling medium in two sizes, say 1/2" and 7/8" with radiused
ends, in an 8" diameter by 12" long horizontal tumbler...

Regards, Myke.

[jeffchem2000]

We have many customers that buy tin who make their own bullets I always assumed that it was to harden the lead but never really thought twice about it. I think they only use the tin in small quantities (a few percent). But yes tin does lower the temperature of lead melting, We produce an alloy that melts at 109 degrees celcius.

Cadmium apparently would harden alloys better than antinomy but it is more expensive and alot more poisonous.

[Anthony]

So is the best media spherical, or cylinders with radiused ends, and why?

If spherical is best, and stainless steel is the most suitable material, then common ball bearings should make a good media.

[Tuatara]

I wouldn't count on 'common' ball bearings being stainless. Most bearings run packed with grease so no need for the extra effort and cost of stainless balls. You would probably need food-grade dry bearings or marine grade bearings to get stainless balls.

I can't see that spherical media are necessarily best, but if you think about it, anything you stick in a ball mill for a day is going to end up round anyway!

[Xioa]

I'm thinking about getting a Lortone QT12 and i want to make sure I get the right amount of milling media. I will probably end up buying from the overly priced United Nuclear, unless someone knows of a better source to buy antimony hardened lead balls. My main question is if i'm getting a 12 lb tumbler, does it need 12 pounds of tumbling material to work optimally? Also, if i need 12 lb for the tumbler to work well, how heavy would United Nuclear's balls be if they come in a pack of 100 and are 1/2" around. Lastly, I already brought this up, but is there a cheaper place to buy antimony-lead balls?

[jeffchem2000]

The ball in a mouse (for a computer!)is steel coated in rubber. If you could get hold of enough old mice I would have thought that they would be ideal - they don't spark and they wouldn't ware out.

[Anthony]

Steel on steel would be a spark risk - the rubber coating would soon wear off.

[Mumble]

I've been using US coinage with out a problem. Its a mix of quarters and nickle denominations. The only thing I don't like is that when I'm milling a moist composition, it sticks to the faces of the coins. Its a pain, and messy, to get off. I have a pretty cheap source for 5% antimony hardened lead shot. Look around in gun reloading magazines. I got this catalog off the internet some where. If I can find it, I'll post the name and where you can get a copy. Its not 1/2", but it goes to at least 1/4" or so.

Another option is to get lead from the scrapyard and form your own in fishing sinker molds. A small amount of antimony could be purchased and added.

[Edit] Alright, found it. http://www.ballisticproducts.com/ It goes to roughly 1/3". Its not extremely cheap, but it's not UN prices either.

[tomu]

Hi there.

just my two cents worth:

I got an e-motor with a gear box at ebay for about US $6 plus shipping it runs at about 90 rpm and has more than sufficient torque.

A piece of copper pipe from a rain drainage pipe about 10 cm in diameter and a lenght of about 40 cm is the milling jar. The ends are pluged by wooden disks.

As media I cut 200 small pieces of brass tubing about 8 mm in diameter and 20 mm in length and fillied each littel pipe with lead. It a sysiphus task but once done they last forever. An alternative is lead wire cut in little pieces. Lead wire can be purchased at hardware shops. Lead balls in different diameters can be purchased at gun shops, they sell them to muzzelloader shooters. By the way you only shoot lead balls and never steel balls with a muzzelloader.

I had no problems to get used hardened lead weights from tire shops for a small tip or even for free. They throw the old lead weights away when they balance a tire. With this lead it's easy to mold your own lead balls. Just take a marble or any other sphere in the right diameter make a mold out of plaster of paris, let it try, molt the lead an pour. Easy.


Have fun
tomu

[hpy2bhre]

My mills are two red plastic rock tumblers I got at walyworld. I use 50 cal lead balls I got from there also for my milling media. The whole deal, two sets total, were about 30 bucks. I used three inch pvc pipe parts for extra jars. these were cheap and i can just make up a jar as my chem list grows.The jars that came with my kits, don't really seal well making wet milling hard to achieve. the pvc ones work well though. I use a threaded cap on one end and a glue on plug on the other. I've let these run for several days non stop and they never got hot or tried to quit. I think if a person made a mill from parts he had around he would need a low speed motor instead of gearing down a high speed one. Keep it simple. Its been said before and is worth repeating that washing machine motors are easy to come by and work well in theses low speed high torque applications.

[Booster]

Hi,

Howabout an electric can opener. That might carry the load, and its slow enough RPM. Check out the local good will or second hand store and cannabalize the parts. Might set you back 4 bucks. With a little creative modification, you could attach a shaft and new chassis, to the thing.

[CommonScientist]

I had a problem a while ago when I was ball milling AN to a fine powder. Everything I used as milling media oxidized, coins , .58 lead shot. Do any of you know of a different milling media that wouldnt oxidize?

I switched from ball milling to a half @ss mortar and pestal made out of an aluminum carrige bolt(they have broad hemispherical ends on them) and a automotive freez plug( pops out when the water in your car freezes , as not to crack the engine block) that actas as a dish. It was rather labor intensive but it gave me good results!

[Mumble]

Ceramic wont oxidise, but that's not the best media in the first place. It will chip and crack. I hear it can also spark(flint in it). That isn't really a problem with most single components though.

Perhaps you should take a gander at the big pos up about 15 or so by Bert. It has many options. Most metals are going to corrode eventually. Pretty much anything at a decent price will undoublably corrode eventually. If you want to mill to a powder without corrosion use glass marbles or something.

[Cyclonite]

Coffee grinders work well with AN, alot quicker also. You really dont need it any finer than that.

[CommonScientist]

Thank you Mumbles and Cyclonite. I have used marbles before but I stoped because I wasnt getting the results I needed. Maybe I needed it in longer(2 hours), quite possibly. I used coins but they turned my AN a dark greyish blue(oxides?) so I stoped using them.

[Bert]

If you've got a small mill, it would take longer than 2 hours. When I was in high school I abused my little rock polisher with a 4" Dia. barrel by using it as a ball mill with marbles. It would take 24 hours to grind a load of BP somewhat well... The larger the Dia., the faster the mill, all other things being equal. Ceramic is good for highly corrosive oxidizers. Stainless steel also.

[CommonScientist]

DUH me. My friend might get me some brass covered lead shot . They are lead shot for a muzzle loader , but they have a layer of brass on them. I would have to cut one in half to see what the thickness of the brass was , as so it wouldnt come off in any form.

Bert - I have a thumblers tumbler, 4" diameter barrel , belt drive. It worked good for the little tiem that i used it. I may have put like 2 pounds of media in it and it still didnt overload it , so its pretty well made. I have a areasol (sp?) teflon lubricant that I spray on the berrings (the wheels that the barrlel rolls on) so I get as little friction as possible.

[tmp]

I use steel slingshot ammo and 1/2" steel ball bearings to grind up
aluminum foil in my Lortone QT12. I'm still looking for a suitable,
heavy, non-metallic media for grinding up chemicals. The ceramic
stuff chips and cracks too much. I'm thinking about using marbles.

[krackerjack9]

How about a garage door opener motor?

Pretty cheap for less than $20 and its going to have the torque to pull up over 300lb garage door should have no problem moving 12lb tumbler around.

http://www.sciplus.com/category.cfm?subsection=18

[DMSOnMyVeins]

you guys ever hit a hammer against a nail kinda crooked? notice all those sparks flying off of it? now think about what a hammer and anils are made of, steel. steel sparks, and milling with steel is not a good idea. i'm not sure about brass, but I think it my spark too. try using hardened antimony lead, no sparks and as hard as steel :)

much safer when milling black powder too :)


Ceramic grinding media can be used, it is extremely hard, non sparking and wont contaminate whatever you're grinding like lead will.

[vod8750]

I recently got some chrome plated steel ball bearings to use in a ball mill. The chrome plating should stop them from sparking off each other at least until it wears off! i dont know how long that will take though!

The only problem is they are expensive as you really need to buy them new to ensure that all the chrome is still on them.

[Jacks Complete]

I'm not sure that chrome plating won't peel after a very short time. It is hard and brittle and likely to chip against other BBs of the same type. Then you would be in trouble!

I suggest doing a test first, with something like sodium nitrate alone, to check for wear and corrosion resistance.

[techtwit]

Take an 8' length of 1X4, support it on a pair of saw horses about 7' apart and try to drive a large nail into it with a 13oz. hammer. Now take that same 1X4, place it on terra firma with the ground in firm contact directly under the spot where you'll drive the same size nail and whack said nail with a 20oz. hammer. The results apply equally to ball mills.

Try this for a tumbler: Using 3/8" rebar and 10 ga. remesh, cast a cylindrical reinforced concrete ring about 14" high, 20" dia., over and around a core made from the bottom 10" of a plastic 5 gal.(US) paint bucket. This makes a very heavy, non-springy tumbler with approx. 4"-5" thick walls and bottom. Cast bolts into the concrete to fasten a wooden (say 1-1/2" plywood) lid and cradle it using casters mounted on a sturdy steel or wood frame. It'd be a good idea to give it about a 30-40 degree back tilt. One or both of the bottom rollers would be powered by say a 1/3 hp. motor via belt and pulley to yield a tumbler speed of 60 rpm. or less.

For media try this: Using a small muffin pan as a mould and wheel weights as alloy, cast as many "hammers" as desired. Their truncated cone shape will give them both a rolling and tumbling action. Wheel weights can usually be gotten for little-to-no cost from garages and tire dealerships, consist primarily of lead with some antimony for hardness, and if the "hammers" are water quenched as soon as they solidify in the muffin pan mould, they'll be considerably harder than 100% soft lead. One could try coating them with a thick layer of epoxy paint to prevent contamination.

This is an untried idea meant only to suggest a good direction to experiment in. The basic principle is that when it comes to any kind of hammering action, the more mass and the less vibration and spring, the better.