Non-Chemical Ball mill has hit a snag

[trashmaster]

Butcher man that was well said ;;

I hope all the mods read that and of course NOXX, He might even even change the name of the forum from GRF to GRU.. or GRUF :roll:

Thanks again for that post it was well said.

 

[ericrm]

can someone help me figure out about how much material will i have to put in a ball mill of 19inch diameter and 20 inch wid
also at what speed i will have to make it turn?

 

[ericrm]

i have probleme with my ball mill...if anyone have a clue about my probleme and how to solve them

i want to pulverise material to chalk like powder...
i have no way of testing the speed but by my calculation when build i was in the correct range... note for those with a brain similar to mine ... to know the speed ,just count them in 1 minute...

it cannot seem to powderise correctly, i have tryed it with many thing from burned material to ceramic cpu and each time im left with big chunck of material..
my probleme are clearly from the conception(im not an enginere, everything made by myself mr clumbsy...) i cannot put enuf steal in it because the motor slide on the strap and/or freeze. i was wondering if 110v motor is realy strong enuf(i dont have the choice to use 110v...)
ring now i have around 15 1-2inch by 2-3inch cut steal stud but is only cover the boton the the mill even with material...

if you know how to improve it ,i will apreciate any info



edit i think one of my proble is because i dont have enuf ball ,the breaking is done when material is hited between a ball and the cylinder rather than between the ball, because of that when im starting it with material it work and do its job but as soon i have pulverised material this material act like a cushion refraining the hiting action... what you think?

 

[butcher]

Hitting a snag is just part of the fun when your building something, your ball mill is looking good now you just need a little more to get in working the way you want it to,

What I see is a very small pulley on the motor, this small surface area for the belt will not provide much friction for the belt when trying to turn the large heavy drum, the motor speed is probably so fast that the motor pulley will just spin and burn the belt (slipping at the motor pulley, which would probably burn the belt at this spot, before the large drum could begin to move), I would think the motor is strong enough to turn the drum but you do not have a large enough pulley to provide the traction.

Changing the pulley on the motor may help, but a bigger motor pulley would also change the speed provided.

If this was my project I would look at several options, changing motor pulley, and possibly adding a drum pulley on the shaft of the drum (I am assuming the drum shaft is welded to the drum), a larger motor pulley and sizing the drum pulley to give the required speed, with this you could also change the type of belt (v-belt and pulleys would provide more traction).

An option to consider is changing your motor pulley and have the motor turn a pulley on another shaft, this shaft also has a pulley on it to turn the drum (adding this intermediate shaft with two pulleys, basically like a transmission between motor and drum, the motor pulley, belt and shaft pulley for the motor can be different from the drum pulley and belt on this intermediate shaft, you could get any speed desired from choosing the pulley sizes.

I would probably also consider other options also like maybe getting a reducer gear box from an old commercial dryer, or other piece of equipment, even something like an old lawn mower transmission to give the power and speed needed, the pulley sizes can also be chosen with these to get the speed desired, also DC motors are very nice as they are easy to change the speed and you can vary the desired speed needed, they can be run from Alternating current by using diodes to get the current converted to direct current (diodes would need to be sized big enough to handle the current).

Gear chains are another option to consider you can weld gears on to sleeves for your shafts, gears and chains from an old bicycle’s (a ten-speed bicycle could give several gears to choose from)

I hope this gives you some ideas, for improving your ball mill.

 

[rusty]

Take another look at Harold's mill, he has a jack shaft between the motor and drum. Small pulley on motor drives onto a larger pulley on the jack , reduced once more with another small pulley on the jack driving the drum.

My best guess is that Harold's mill was running well below 50 rpm

 

[ericrm]

those are good tough.
i think i will change my motor to make it 1hp rather than 1/2hp, hoping that this will allow to run the mill half full of material.
im also thinking if theyr is a minimum size for the cylinder(barel) to work properly? would 12 or 14 inch diameter be enuf??
and i think i will folow your advise butcher on the new ballmill and put 4 or 6 pulley rather than just 2

good news i found real steal ball (the round one :lol today rather than my cut stud...

 

[qst42know]

Might be a trick of the camera but It looks like your belt is upside down, at least if that is a V-groove pulley.

 

[ericrm]

Might be a trick of the camera but It looks like your belt is upside down, at least if that is a V-groove pulley.

no it is a car strap ... :roll: but it did the job in this setting...

 

[ericrm]

i have found on wiki the equation to count critical speed
nc=42.29/√d
in my case i will make the barrel 12 inch
so we have
nc=42.29/√0.3048
nc=76.6

is this sound ok?
also wiki said the ball mill use should be around 75% of nc, but i have read somewhere else that the speed should be 65% of nc. so i guess that if im between 65% and 75% i will be ok?

76.6rpm x 65% = 49.79 rpm
76.6rpm x 75% = 57.45 rpm

what you think?

 

[goldsilverpro]

Here's a thread on which this was discussed

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=3107&p=27909&hilit=ball+mill+rpm#p27909

 

[ericrm]

thank you gsp ,that post has confir m my calculation 8)

 

[ericrm]

a picture of the new machine ,still in progress.
the strap still slide so im looking for a bigger pulley

 

[butcher]

ericrm,

That is looking good, is that a gear reduction between the motor and the idler shaft?

 

[ericrm]

yes , ive been lucky enuf to find 2 real cheap ,here is the final product

 

[butcher]

Nice

 

[ericrm]

thank you
im happy with my work, i will know for sure tomorow if it powderise material as expected

 

[butcher]

Keep us posted.

 

[rusty]

Here's an idea for those wanting to build a ball mill, I just wrecked out an old Cub Cadet Zero turn mower you may find similar hydrostatic drives on other mowers.

Each rear wheel has it's own independent pump and drive motor, the beauty of hydrostatic is that the motors have plenty of power with fine control over the RPM's, you have several options to drive the drum.

You could use the tire as a friction drive, or remove the tire and add a chain sprocket or V-pulley in place of the tire or make a drive shaft to direct couple your hydrostatic drive directly to the drum. Speed control is easily controlled with the touch of a lever as is forward and reverse.

Most machine and jobber shops make up hydraulic hoses with any end fitting you may require at a fairly reasonable cost. No I'm not planning to make another ball mill just throwing the idea out there for those of you that want a cheap mill.

You can use an old 20 lb propane tank for a hydraulic oil reservoir, run the tank about 2/3 full and make sure your return line is well below the oil level to avoid foaming. Any air in the system will cause cavitation and over heating. For a system this size you shouldn't have to worry about an oil cooler.

Best Regards
rusty

 

[butcher]

Three point ball mill for my tractor :twisted:

make a good cement mixer also.

 

[rusty]

Three point ball mill for my tractor :twisted:

make a good cement mixer also.

The typical P.T.O. shaft can wrap up 424 feet of shoe lace in one minute at 540 rpm, or 785 feet of shoe lace at 1000 rpm. How long is your shoe lace?

A bit fast for a ball mill, you would need a reduction of some sort.