Jump to content


Ball Mill Project

  • Please log in to reply
37 replies to this topic

#31 dr thrust

dr thrust

    Pyro Forum Top Trump

  • General Public Members
  • PipPipPipPip
  • 1,402 posts

Posted 18 August 2012 - 07:30 PM

to find your optimum milling speed it needs to be 65% of the "critical speed" this being the speed when your mill acts as a centrifuge and all your media sticks to the side or your milling jar lol. critical speed = 265.45 divided by the square root of your milling jar diameter (inches) minus the media diameter.? im pressuming its 1/2"
so for a 8" jar with .5" media 265.45 / 7.5 sq... so this = .. 265.45 / 2.73861... then is = 96.928 rpm /65% = 63 rpm
for a 6" jar optium speed 73rpm
edit just done the calc for 3/4" media and get the same result 63 rpm ,i personally think anything around the 60's will get you great bp, i use 3/4" lead media cast like this simples!
Posted Image

Edited by dr thrust, 18 August 2012 - 07:40 PM.

#32 Sparky


    Pyro Forum Regular

  • General Public Members
  • PipPipPip
  • 458 posts

Posted 25 August 2012 - 04:30 PM

does anyone use two barrels and share the charcoal between the other two ingredients

and mill separately then either mill together for a short period or sieve together?

I've read about this double milling method and it appeals to me too as it does mean you are essentially milling as non-explosive composition in each jar. I can't imagine it will make BP as good though but I think it is worth a try and as long as I get BP good enough for lift then I'm happy.

I've tried the CIA method too and frankly the BP is piss poor compared to what I've seen some people on here achieve with a good mill. I can't wait to mill my first little batch of BP.

Next task is to make some lead media Posted Image

#33 Mchagis


    New Member

  • General Public Members
  • Pip
  • 3 posts

Posted 14 November 2012 - 10:09 AM

Just wondering if someone can point me in the direction of a roller supplier. UK based.
I guess if I knew exactly what their technical name was I could find them easier. Putting roller into Ebygum produces everything but what I'm after.

!!! Eureka
Take one or two old dot matrix printers, extract the carrier bars and add bearings. Should be a bag full of cogs and bits which may come in useful on another project, in the future, sometime, maybe ......

Edited by Mchagis, 14 November 2012 - 11:32 AM.

#34 barnsley-mark


    Why did I try that?

  • UKPS Members
  • 119 posts

Posted 14 November 2012 - 08:42 PM

I use conveyor rollers off eBay, very cheap from china,

#35 cooperman435


    Pyro Forum Top Trump

  • Admin
  • 1,907 posts

Posted 15 November 2012 - 08:48 AM

I had the same issue and ended up makign my own from 20mm threaded bar and tubing I had made especially for the job. Very sturdy and fritionable (is that a word? if not I like it!) and also easy to replace the surface of if ever needed.

#36 Sparky


    Pyro Forum Regular

  • General Public Members
  • PipPipPip
  • 458 posts

Posted 16 November 2012 - 11:01 AM

I made my own too with 20mm aluminium bar, pillow bearings and heat shrink covering.

#37 michaelp



  • General Public Members
  • PipPip
  • 25 posts

Posted 19 November 2012 - 10:46 AM

I have got my .75hp motor for the mk2 version, the little 12v motor i got off ebay for 7 quid is working well, mounting it on ply with two wooden curtain poles for rollers,it came with a drive sprocket and belt, after running 6 hours its as cool as a cucumber i moulded some 20mm lead slugs by pouring it into two layers of plywood, screwed together, they were still a bitch to get out but i made 40 in one batch.
I drove them out using a socket set, after the first run they were smooth.

I must be sad but i find watching the drum spin is quite therapeutic, being a mixture of my handiwork and a time served recipe, albeit a tad noisy.

#38 michaelp



  • General Public Members
  • PipPip
  • 25 posts

Posted 19 November 2012 - 12:32 PM

<a href="http://www.flickr.co...03/8198815171/" title="IMAG0326 by xmickyp123, on Flickr"><img src="http://farm9.staticf...b1281e7c_s.jpg" width="75" height="75" alt="IMAG0326"></a>

Here she is, the motor as i said was £7 on ebay,.....bargain

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users