635 replies to this topic

[Night Owl]

Yeah I was gonna get that one but was wondering with them being so cheap will they hit me on postage, guess ill fone them and see how much all in

[pyrotrev]

As I've posted before, I've had some problems with the Beach tumbler, with barrels not turning, or if you add some rubber bands to improve grip, them hopping off when you get a decent charge + dense milling media. The Evans Junior tumbler with it's "uphill" drive would appear to perhaps be a better option from a theoretical standpoint, though it's possible to modify the Beach to work in a similar manner.

[Night Owl]

OK I take it the Evans Junior is on a different site as I cant see it on there so as I (sorry) dont have the time to search all post's) will order the blue one lp0005 beech

[cooperman435]

Just completed the construction of my first ball mill and I’m quite pleased with the result.

For those of you about to make one I discovered from some motors I had laying round from past projects that an invalid carriage (disabled persons "buggy") motor and connected gearbox conveniently turns at about 90 rpm!

So a piece of 4" drain pipe and 2 screw on end caps, a brass central pin bolted in that has a threaded end to fit into the existing drive shaft, a few bits of MDF and a power supply has made my ball mill.

I’m only finding two problems firstly the power supply isn’t really rated for a high enough constant supply so gets a bit warm after 3 hours so I need to find a higher rated one.

And the one I cant understand is that I’m using brass balls that I’ve machined from bar if that makes a difference? The powder is as far as I know dry when put into the mill but it seems to stick to the walls? The more I mill it the worse it seems to get and this has got to be affecting the efficiency of the milling?

Any ideas guys?

[portfire]

hi there cooperman435 . i too built my mill from scratch . i used a old washing machine motor . the rollers are 3" pvc pipe 'mdf center with 8mm threaded bar and i used skateboard bearing's . it turns at 80-90 rpm.i will try and post some picture's soon .
ps. i too have the same problem with the powder sticking to the jar . is this normal ?

[BrightStar]

The powder is as far as I know dry when put into the mill but it seems to stick to the walls? The more I mill it the worse it seems to get and this has got to be affecting the efficiency of the milling?

Same problem here with the powder sticking to the walls. I thought it might be because my mill is too fast (it has gone a bit psycho recently and is spinning the 4" jar at 130 RPM). I just stop it every hour or so and dislodge the sticking powder which is a bit of a nuisance.

Also, does anyone have any tips for cleaning the jar and media after use - I tried milling cat litter bentonite and it really messed it up...

[EnigmaticBiker]

And the one I cant understand is that I’m using brass balls that I’ve machined from bar if that makes a difference? The powder is as far as I know dry when put into the mill but it seems to stick to the walls? The more I mill it the worse it seems to get and this has got to be affecting the efficiency of the milling?

Any ideas guys?

I can't see it being a problem with your balls.

My mill is variable speed (windscreen wiper motor) and I did notice that at higher speeds the (dampened) BP tended to stick to the walls, turning the speed down, it transferred to the media; centrifugal force versus adhesion perhaps?

[cooperman435]

cant really see centrifugal forces being enough on their own to stick the powder to the walls otherwise the balls would do likewise?
I suppose that it would help an already slightly sticky powder adhere better though.

Did anyone else have this problem and manage to stop it?

Im thinking that maybe the powders are not actually that dry and that as the particle sizes get smaller the contact points between them gets more and more so the same amount of moisture has a greater effect?

Im gonna try putting the individual component powders on the boiler for a day with my media and the milling container to try to get rid of any moisture. Lets see how I do.


BTW anyone out there know enough about electronics to tell me how to work out the power requirements of the motor so I can search for a suitable power suply? 3 hours with a 1 hour down time is boring to have to keep remembering on and off times?

[rx7-dan]

right im getting a ball mill, found it on ebay, its a 3lb one but doesnt come with the media i need, can any one tell me how much and what size lead bells i will need? thanks

[portfire]

as i understand it the jar should be filled halfway with your media and a 1/4 with powder so the jar is 3/4 full . as for the size i think you want to be looking at around 20mm in diameter. hope this has helped in any way

Edited by portfire, 16 December 2006 - 05:07 PM.

[cooperman435]

as i understand it the jar should be filled halfway with your media and a 1/4 with powder so the jar is 3/4 full . as for the size i think you want to be looking at around 20mm in diameter. hope this has helped in any way

The size of the jar is not importaint really just the speed of it turning which there are posts previously in this thread explaining the maths required to get the optimal rpm speed for a jars size.

It is suggested that the milling media is 1/2 of the jar but the powder contents are 1/4 to 1/3 of the EMPTY jar so as the media is made of balls which have gaps between them the combined contents are unlikely to appear to take up much more room than the media alone.

Media is usually 1/2" hardened lead balls (or brass) for bp milling or steel/ceramic for single compounds.

There now you know!

[Asteroid]

Add in some gears to the workings of a washing machine, take out the water pipe and and presto, one very high load ball mill

[karlfoxman]

Do you mean using a washing machine as a ballmill?

[Spudgun]

Add in some gears to the workings of a washing machine, take out the water pipe and and presto, one very high load ball mill

***EEEK***

[newtoolsmith]

@cooperman435:

thats not really correct.

The jar size is very important! Remember that the media travels some way upwards along the inner jar wall and then fall down again. When the falling media smashes the particles you mill, the potential energy, transformed into kinetic energy, is used.

The higher the media is carried upwards, the more energy will be available. A big jar diameter is what you need therefor.


The media should have 1/3 to 1/2 of the jar volume. The milled substances volume ( called grist? ) should be big enough to fill all the room between the media and some more. You should not see your media any more.


The media size will greatly influence the particle size you can achieve. The bigger you media is, the bigger the final particle size will be. To get the finest possible particles, you can use some big media together with some much smaller media. The small ones will fit into the holes between the bigger ones and the milled substance will be brayed and smashed.



Very simple time circuits can easily be made using the NE555 or NE556 IC. Such circuits are available on the net.

Do you need a speed regulation too? What Type of motor is it?



My BP tended to stick to the walls too when I used damp mixtures. Now I use really dry chemicals only and have no problems. Due to the higher danger the mill does its work outside, far away...


@Asteroid:

Washing machine? Not as bad as it sounds...

One could use motor, electronics (modificated), belt and wheels.


MfG
newtoolsmith