ball mill

[memo]

i have a pvc tube ball mill, how warm should it get when milling bp,i run it for 5 hour and at the end of the run it is warm. is there anything to be concerned about ? when i mill carbon it doesn;t get warm.

 

memo

[calebkessinger]

You should mill just lead balls by themselves like I do..

I let mine run overnight. they are almost too hot to touch come morning.

 

oh, I have no idea how hot is too hot.. I run mine in a running freezer in the summer.

[memo]

after 5 hours they are warm - hot , but not real hot.... reading about the blow ups a few guys have had milling bp made me ask.

 

memo

[BurritoBandito]

Generally speaking, it seems as though the danger is more prevalent while emptying the jar than while milling. In my case, I was using an unsafe media (marbles), and I shook the jar when the powder caked up. Those are pretty big no nos. Using lead, and following the accepted milling methods, the probability of an explosion is relatively low. No one really knows what happened with Dagabu's accident, but it happened as he unloading his mill.

[mikeee]

Not sure if all of the details ever came out on Dagabu's accident or not.

If my memory serves me well I think there may have been a HF style star roller

being used for mixing some BP type comps.

 

Does not really matter what the equipment is, the main issue is making sure it is grounded

and the person handling the material also needs to be grounded in an equal potential plane.

Touching a grounded metal surface is a quick way to discharge the energy in your body prior

to opening a container with energetic materials. You also need to ground the container to

discharge any potential difference between you and the container. The best way to resolve

this issue is a ground strap on your wrist and a ground strap on the container. A stranded

wire with an alligator style clip works well for quickly attaching to an object. If you don't

take these precautions, the least you can do is touch a grounded surface and pick up the container

this should bring both objects to the same potential.

 

Bouncing marbles around inside a mill jar, well..... I don't think there is anything we can do to

prevent a potential ignition of energetic materials like BP etc. Lead or SS milling media will reduce

the potential ignition source, maybe treating the material like a potential B.O.M.B. (which it is)and

handling the material gently like it was flash, would reduce the number of accidents.

 

Burrito, hope you are healing up and making progress from your incident.

[BurritoBandito]

I'm doing well, thank you Mikeee. I returned to work exactly 3 months after my accident, and am capable of doing everything I could do before for the most part. Guitar and piano are still a bit sloppy, but I'm slowly getting back up there. Certain chords are nigh impossible to do, and holding a pick is awkward, but I can still play. Thing that messes with me the most is actually forgetting that I'm missing a pinky. I'll say 5 and hold up my right hand, then look and realize that there are only 4 fingers there. It's usually good for a laugh.

 

I seem to remember Dagabu was actually using a modified cement mixer as a ball mill. I doubt all of the details will ever surface. Primarily because Dagabu doesn't remember them himself. Suffice to say, he is still in business. Dagabu is, IMO, a master craftsman, who offers some beautiful looking tooling. Words can't express my respect for his strength, perseverance, and kindness.

 

EDIT: One thing I'd like to add is that I know PVC is a common choice for DIY mill jars, but I, personally, advise against it. Granted, we should be taking all possible precautions to avoid having unintended explosions, there are no garuntees. Had my jar been made of PVC, it is likely that I wouldn't be here today. PVC has a tendency to shatter into sharp, jagged, pieces of hard plastic. The thought of being peppered by the debris of a PVC jar exploding is one that I think we should all take very seriously. Just my 2¢.

Edited May 15, 2015 by BurritoBandito

[mikeee]

No different then using a pvc pipe for a rocket motor tube, you don't want to be any where

close to one of those motors when the cato.

[BurritoBandito]

In spite of the fact that I've made many motors using PVC in the past, I would no longer suggest it's use there either.

[memo]

for the diy type guy , what would you use for a mill jar ? hdpe ? or ?

 

memo

[BurritoBandito]

HDPE would be good. If you could find/fashion a rubber jar that would be ideal.