635 replies to this topic

[Arthur Brown]

"Safe" is always relative, and as I have never come across a planetary mill before I haven't anything to relate it to.

If it is as good as you say, then preparing ingredients will be a time consuming chore reduced dramatically. You may even find that it goes past the optimum particle size for some compounds rather quickly. -sparks or trails are usually coarser powders or even metal swarf.

Firstly see if you can get the lid to work, a quiet mill means quiet neighbours!

[phildunford]

I've mentioned planetary mills here before, but no one has ever seemed very interested!

I'm actually in the early stages of building one.

The upside and the downside is that they are much higher energy devices than conventional ball mills. This means they will mill very efficiently and very quickly, but the contents get much more of a pounding.

This will produce more heat and the powder will be subject to more impact. Now I suspect this will not be a problem with black powder type mixes, but I will cretainly be running it somewhere very safe and I will be checking the temperature of the jar contents at first to get some idea of what is happening...

[Greenman]

I've mentioned planetary mills here before, but no one has ever seemed very interested!

I'm actually in the early stages of building one.

Sorry, as i am a little new to this forum i have not read the whole thread yet.
Building one yourself? Thats not a easy task I suppose you will buy the jars? Mine is using two 10cm ID. rock hard jars made of quartz. I am not sure, but i recall reading that one could use jars of alumina. In that case, it would be possible to make yourself.

Tomorrow i will try going on slow speed with a batch of BP. All safety measures possible are taken, but i am still feeling a little bad about this. I know the lid is supposed to deal with an eventual explosion from inside, but the a jar of ceramics tightened up with locking mechanism half full of BP would be pretty bad.

My greatest concern here is that somehow the temperature will rise within the jar and make the BP go off. I have not read the whole manual yet, but i am to understand that the locking mechanism will release itself when a given temperature is reached within one of the jars. It is also possible that the balls, having higher speed than in a normal mill, will produce sparks. However i doubt this. Taking in account that this was designed to use by proffesional chemists, i dont think they would let such i danger come into play without mentioning it. But as said, its never "safe".

I will post the results of my test.

Does anyone in here know how much time one acctualy does save by using this kind of mill?

[phildunford]

The jars and media are not really the issue for me - it's the planetary gear mechanism - I'm using lathe changewheels for this, but still a tricky project! - Still, that's half the fun!

Although temp rise is a possible concern, at least that can be measured. My worry is more the impact from flying balls(!) BP can be initiated by impact. Guess only trials will prove this point.

I suspect it will be hugely quicker - I think half an hour in one of these devices will probably be the same as 24 in a conventional mill.

[knackers]

one thing to keep in mind with a planetary mill is the friction created between the media and jar wall, it is tremendously higher !, than a rolling ball mill

[Greenman]

Today's results were rather positive. It turned for 45mins with 50grams of BP in each jar. Nothing special happened to the temperature. Nor did i notice any signs of sparks in the jars. The BP which was a plain greenmix at start is now lift quality. 45min lift is, for me, a great save of time.

So I will continue using it, as it worked out good today. However one should not conclude potentional safety with a single success. Il put a warning if anything goes wrong.

Stay safe

Edited by Greenman, 22 May 2009 - 03:45 PM.