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Homemade ball mill


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#1 Svimmer

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Posted 21 December 2017 - 03:17 PM

Hi would you guys say this is about right speed or little to fast. Sounds like the media falls like it should.



#2 PeteyPyro

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Posted 21 December 2017 - 03:20 PM

Sounds a little fast and looks fast for anything over 4 or 5 inches in diameter, which would be tiny indeed. What is the jar's diameter?
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#3 Svimmer

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Posted 21 December 2017 - 03:25 PM

Sounds a little fast and looks fast for anything over 4 or 5 inches in diameter, which would be tiny indeed. What is the jar's diameter?

 

Its not more then 2.9 inches



#4 OldMarine

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Posted 21 December 2017 - 05:02 PM

That looks like around 150 rpm which I think is pretty close to optimum for a 3" jar if only a little too fast. Lloyd has the formula to figure all of that in his book but I have no idea how to type that math crap. I'll see if I can get him to chime in.


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Come on! Name one other hobby in which you cheer as your money and hard work go up in smoke!

#5 Col

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Posted 21 December 2017 - 06:13 PM

Needs to be around 108rpm if its half full of media, it looks like its going quite a bit quicker than 108rpm.

Curiosity got the better of me, its doing 200rpm  ;)


Edited by Col, 21 December 2017 - 06:31 PM.

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#6 PeteyPyro

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Posted 21 December 2017 - 09:10 PM

That looks like around 150 rpm which I think is pretty close to optimum for a 3" jar if only a little too fast. Lloyd has the formula to figure all of that in his book but I have no idea how to type that math crap. I'll see if I can get him to chime in.


I can't type 'scientifical' stuff well, but I found a pen and paper. ..15139111699272028247215.jpg This equation from Lloyds book is to calculate the 'critical speed'. You'd probably want to run at 'optimum speed' for dry powders, which is about 65% of critical speed. With the diameter of your media (1/2" balls ?) and the INTERIOR diameter of your mill jar, you can calculate the critical speed required, and the by multiplying this by 0.65, you'd arrive at a reasonably optimum speed. I should have asked you what size your jar's interior diameter and media size are, in order to give you a more responsive reply.
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#7 Svimmer

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Posted 22 December 2017 - 12:33 AM

Jar diameter: 3inch

 

the rod its spinning on is 1.2 inch

 

Atm i use marbles as media because thats what i had.

 

and 50% media.


Edited by Sondre, 22 December 2017 - 12:49 AM.


#8 Boophoenix

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Posted 22 December 2017 - 01:46 AM

Sounder, marbles have been linked to more than a few oopsie's if I recall correctly. Please be sure to set this up remotely away from you and most especially others should you be milling BP if you choose not to change media.

If you're going to continue to use the marbles after being warned slow the mill way down. To the point you barely get a cascading effect of the media if any at all to help prevent chipping and shattering the marble. This will cause a loss of efficiency and extend milling times. This may could help with the down sides some, but I wouldn't count on it.
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#9 Svimmer

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Posted 22 December 2017 - 03:54 AM

Sounder, marbles have been linked to more than a few oopsie's if I recall correctly. Please be sure to set this up remotely away from you and most especially others should you be milling BP if you choose not to change media.

If you're going to continue to use the marbles after being warned slow the mill way down. To the point you barely get a cascading effect of the media if any at all to help prevent chipping and shattering the marble. This will cause a loss of efficiency and extend milling times. This may could help with the down sides some, but I wouldn't count on it.

I thought glass marbles was ok to use but not the best ?



#10 MrB

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Posted 22 December 2017 - 04:54 AM

I thought glass marbles was ok to use but not the best ?

Where is BB, and his missing marbles when we need him?

 

Anyway. Just... No. BB used glass marbles, and had the mill go boom on him, if i recall right, when emptying it. Don't mill live compositions with marbles. And don't mill chems you once milled with marbles, as a part of live compositions.

 

Edit

Ok, i made a quick search, but i cant come up with the thread.

BurritoBandito used glass marbles, had run a milling pass on BP, and was emptying the mill. Seeing BP clumped together, sticking to the walls of the jar he shock it, and it grenaded in his hands. Lost a pinky, but survived mostly scared, rather then "actually" harmed. Having a bomb go of, shooting glass marbles in all directions, just losing a finger isn't really that bad. Staying alive, is something of a miracle. Which is why i would suggest switching from glass media...

/Edit


Edited by MrB, 22 December 2017 - 05:04 AM.

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#11 Svimmer

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Posted 22 December 2017 - 06:44 AM

Where is BB, and his missing marbles when we need him?

 

Anyway. Just... No. BB used glass marbles, and had the mill go boom on him, if i recall right, when emptying it. Don't mill live compositions with marbles. And don't mill chems you once milled with marbles, as a part of live compositions.

 

Edit

Ok, i made a quick search, but i cant come up with the thread.

BurritoBandito used glass marbles, had run a milling pass on BP, and was emptying the mill. Seeing BP clumped together, sticking to the walls of the jar he shock it, and it grenaded in his hands. Lost a pinky, but survived mostly scared, rather then "actually" harmed. Having a bomb go of, shooting glass marbles in all directions, just losing a finger isn't really that bad. Staying alive, is something of a miracle. Which is why i would suggest switching from glass media...

/Edit

Alright im going to get some leadballs 


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#12 PeteyPyro

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Posted 22 December 2017 - 06:51 AM

The thread that I remember from Dagabu about BB's accident:

https://www.amateurp...on/#entry128158
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#13 Svimmer

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Posted 22 December 2017 - 09:06 AM

Is lead balls lead balls if you know what i mean :D

https://www.ebay.com...VQAAOSwCfdXoejt

Whould these work ?



#14 Col

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Posted 22 December 2017 - 10:52 AM

Hardened would be better as they dont wear. With a small mill jar i`d go for ceramic cos you dont need a lot.


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#15 Arthur

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Posted 22 December 2017 - 01:19 PM

Balls about 10mm might be OK. Ceramic balls are hard enough but less dense, however that assists when you have a small mill motor. 

 

https://www.inoxia.c...amic-balls-13mm

 

is a good UK supplier. 


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#16 Col

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Posted 22 December 2017 - 02:52 PM

Best to shop around, £17 for a kilo with delivery.is a little steep



#17 MrB

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Posted 22 December 2017 - 03:16 PM

The thread that I remember from Dagabu about BB's accident:

 

That's the one i couldn't find. Thanks.

 

 

Hardened would be better as they dont wear. With a small mill jar i`d go for ceramic cos you dont need a lot.

 

Don't wear as much. Lead is still a consumable as milling material. I think my BP balls lost 2 mm over the last year. I'm at the point where i will have to recast them soon. I'm using 50/50 wheel weights, and commercially recycled lead from Boliden Bergsöe. (pretty much as pure as it gets, i suppose. Just happened on a bar, if i was paying for it, i would have gone with a 6% antimony variant.) Anyway, the lead hardens pretty well, but i have no real way of measuring it. Just comparing water quenched vs slow air cooled by pressing them, and such.

I'm sort of considering switching to ceramic, mostly for environmental reasons. Less lead in the end product, so to speak. Not entirely sure what i would do with all my lead at that point. I don't need THAT many lead hammers.

 

Also... If someone ends up buying lead that isn't hardened, but does contain antimony / arsenic to let it be hardened, could simply toss it in the oven at 225c, or so, and then drop them in to cold water, to set them of.


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#18 Col

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Posted 22 December 2017 - 06:03 PM

Hi B.

doesnt wear as fast is what i meant ;) Lead and ceramic have their own plus`s and minus`s so the best option is to have both in seperate mill jars.



#19 Svimmer

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Posted 22 December 2017 - 06:27 PM

Well overall i think the mill can work pretty good for the money :D 

 

Cost me under 4$ to make lol



#20 calebkessinger

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Posted 22 December 2017 - 07:39 PM

Can't argue with the price!
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