Finally got a ball mill, Tips?

[Phil]

30 minutes of mill time is all it took. Significantly better.

[cmjlab]

I'm glad you were able to get some lead balls, they will be immensely more efficient and safer than glass marbles.

 

The wobbling and walking of the jar are likely simple fixes. The wobbling is probably because you have more weight in your jar which moves the center of gravity. To fix that, I bet you need to widen your rollers a little. It may take some expirimentation - un-attach one of your rollers, have your mill jar (with lead media) and place it on the rollers and line it up to a point where it's slightly wider than where it was, then see if it rolls freely without trying to wobble off the rollers.

 

For the walking of the jar, I believe this is a common issue for people like us that build our own ball mill. We can't get the two rollers "perfectly" aligned no matter how good we are. If it walks too much/fast, then the alignment of your rollers probably needs to be fixed. If it walks a little, and goes to one end, then put a roller (I used a kids training wheel and bracket) to block the barrel from walking off the rollers, but still be able to spin freely.

 

Hope some of that helps - either way I think you will happier with the heavier milling media. As long as you use it for B.P. milling and not run it empty (beating against only other lead media), I don't think it'll wear down on you as fast as you think.

 

Charles

[Arthur]

Some rock tumblers have a ball bearing at each end to limit the travel of jars.

[Phil]

Yeah it's certainly the added weight. The problem isn't as bad with the marble jar and both of them run acceptable on my flat desk (dummy loads). By widen the rollers I take it you mean the space between the drive and idler shafts. That would seem to require a bit of fabrication as this doesn't seem to be adjustable. I did however cobble together some small rollers on the side and end with junk I had hoarded.

Edited November 20, 2022 by Phil

[justvisiting]

Phil, what size and kind of rockets are you making? Nozzleless I assume?

[Phil]

Before I got the mill running I was doing nozzled because my powder was too weak, I made my first nozzless rocket yesterday and it flew pretty good so I'll probably be going that way from now on. They're the 5/8" ID "cohete" style nozzleless rockets on calebs tooling.

 

[justvisiting]

That got up there

 

I assume you used the same tooling for the nozzled rockets? Just FYI- in case you didn't know- the cohete tooling has a shorter spindle than standard BP rocket tooling. With the standard tooling you get way more thrust. If you add some coarser 40-80 mesh charcoal, (say 15%) to your new improved powder, you could put a nozzle in the cohete rocket and get a nice tail too. Lots of ways to go with rockets, which becomes more obvious as time goes by

[Phil]

Thanks, same tooling. I learned a bigger spindle is better of course after I bought this set lol. Not to say I'm not satisfied, a year or two ago I was able to make a few rockets with this set that lifted 100 grams of flash using screen mixed powder. I don't know how I pulled that off but it was more than enough boom for me. I had some sorted mesh sizes of charcoal but I converted it all to powder, it was all ERC though. I take it for effects you want to use hardwood right?

 

[justvisiting]

Yes, busted up, screened barbecue charcoal would work just fine.

[cmjlab]

Yeah, my bad, you are right of course (you can't move the rollers apart), I was thinking you built your own mill for some reason.

 

To prevent walking, do you think maybe gently shaking the mill jar to evenly spread out the media inside, prior to starting the mill would help? (Assuming that the media is all towards the bottom once you add the media and powder to be milled - if all the weight is on one end when the mill starts, I could see it start to walk the jar off the mill, until the tumbling evens it out.

 

Just a thought, hopefully you figure it out! Good luck!

 

Charles

[Arthur]

Mill jar walking is likely to be caused by something not being truly round or parallel sided. Likely you will have to fit a mobile stopper wheel to hold the jar where you want it. Anything from a 10mm ball bearing to a skateboard wheel. Either should be fitted so that it turns freely when driven by the drum resting on it.

[Phil]

I cleared out the pit and setup the mill for another run. This time I had it on a very slight tilt to where the jar is biased to lean against the black roller I made on the motor end. I peeked at it 10 minutes in the run and it seemed to be working pretty well, with the extra roller working as intended. I'm still pretty paranoid about it though. I keep wanting to check on it. I know someone earlier in the thread mentioned a remote camera. Do you guys have any experience using things like this to monitor your mills remotely? 1080P HD Mini Wireless Camera Spy Camera Wifi Home Security Camera Night Vision | eBay

[cmjlab]

I haven't, but I spose if that's how you can mitigate more risk then good on you! And it ought to work nicely. As you likely know, they are pretty easy to setup these days, just download app / scan UUID, app sets everything up for you to remote view, ez-pz!

 

Charles

[SharkWhisperer]

Yes, busted up, screened barbecue charcoal would work just fine.

screened "lump" bbq charcoal, not the briquettes that amazingly some folks still try to use. Those have clay and/or other binders and a bunch of other crap in it, on top of being mediocre pyro charcoal to start with. I used Cowboy brand lump coal a few years ago, to good effect, but now it seems to be sourced from all over the world so you can't really expect reproducible results from bag-to-bag (source country used to be printed on bottom of bag).

 

Lump charcoal will do, but making your own or finding a trusted vendor is important for reproducibility. Especially with rockets, you want consistency. Especially if you're launching large(ish) flash payloads (that is not the time to be guessing).

 

Briquettes? They are good for nothing at all, whether pyrotechnic or bbq in nature...

[Phil]

Briquettes? They are good for nothing at all, whether pyrotechnic or bbq in nature...

I can't light a pile of briquettes to save my life. They're good for making a mess and producing maximum ash with minimum heat though. Sure it's something I'm doing wrong though lol.

[Phil]

100 gram dummy heading. It's neat to me how much this little 40 gram motor can lift. The entire device weighs almost half a pound. The thrust doesn't seem to last very long but it seems to have some pretty good momentum by the time it stops burning. Felt top heavy so I put two sticks on it. Not that I need to but I'm doing another mill run one last time for the meantime to see if I can make the powder any better. I'm sure there's a point where the diminishing returns start to set in.

 

[cmjlab]

Any updates? How did it work out?

 

Charles

[Powderman]

So here I am to report that my 304 SS balls arrived yesterday. I have only tested with magnet and checked the quantity, all seems OK. Each ball is exactly 3g, total 3kg for 1000pcs.

In the meantime I have successfully made some fine charcoal stuff in my "hand shaker" with 200pcs of 6mm SS balls in plastic pill bottle. It only takes to watch few videos/movies while shaking :-)