Guesstimating Ball Mill media charge?

[MondoMage]

I'm gathering up the bits and pieces for my first ball mill, and for my first jar I am going with a Sponenberg-style 6" jar. I'm still waffling a bit on the media I want to use in it, and one of the concerns I have is how much media I'll actually need. What with my having to keep within my budget to keep the wifey happy, I definitely don't want to go overboard on purchasing the media right now. I know that the optimum charge is 1/2 of the jar volume, but I was wondering if there was any rules of thumb for determining how much that actually is? That is, for a 1 gallon jar, what does 1/2 gallon of media weigh? Aside from the fact that lead weighs more than zirconium media, I'm a bit in the dark.

 

Anyone have any pointers that they're willing to share?

[warthog]

Lloyd S gave me this formula to get the amount of media needed for a given jar:

 

For Media Needed per Jar

Fill jar with water and measure what it took in US Gallons then multiply that number by 29 US pounds. That gives the amount of media by weight for any size LEAD media of any shape. That said, he also says that 1/2" DIAMETER CYLINDERS are the optimum type of media for all size of jars period. Never mind what he said in the book before, this is what he says has been borne out by his research since then.

 

Charge per Jar

Take the same number of US gallons from before and multiply this by 600-800 grams and then futz with that until you find what works best for your jar.

 

Hope that helps out. I only use lead as I cast and it is cheap and easy for me.

[Arthur]

When milling coarse powder down ball media gives a bigger range of product size than cylinder media. Cylindrical media tends to give a tighter product size range.

[oldguy]

Ordinary glass marbles range in size from 9/16ths to 5/8ths of an inch.

 

The internal dimensions of a PVC ball mill jar vary depending on the thickness of the wall.

 

You can get a “ball park” figure of how many pieces of media you need to fill a jar ½ way.

 

By simply filling it half way with marbles. Then count the number of marbles it took.

 

 

[Leadballs]

... That is, for a 1 gallon jar, what does 1/2 gallon of media weigh? Aside from the fact that lead weighs more than zirconium media, I'm a bit in the dark.

 

Anyone have any pointers that they're willing to share?

 

Yep, !/2 inch lead media weights exactly 11.6 pounds per quart. 25 pounds rolls dandy in a standard 1 gallon jar. For more about this, see the market page at Passfire, right hand column, 2/3 of the way down "Super Hard Lead Mill Media" http://www.passfire....rket/market.asp

 

 

 

 

(please excuse the shameless plug

[dagabu]

Ordinary glass marbles range in size from 9/16ths to 5/8ths of an inch.

 

The internal dimensions of a PVC ball mill jar vary depending on the thickness of the wall.

 

You can get a "ball park" figure of how many pieces of media you need to fill a jar ½ way.

 

By simply filling it half way with marbles. Then count the number of marbles it took.

 

 

 

Just a reminder, just use the marbles to measure the fill of the jar, don't use them to grind chems, especially reactive comps. There were many friction machines invented in the 1800s that used glass and rubber or wool, or silk to generate a significant static charge. One of the earliest was invented around 1663 by Otto von Guericke, using a sulphur globe that could be rotated and rubbed by hand. Glass marbles and sulfur = static generation.

 

-dag