ball mills

[clarkie752]

I have been making fireworks for a year now and I love it. My only problem is now that I am making more stuff than I am buying I was wondering what type of ball mill to get to make bigger batches of black powder in 1 run. I currently have the 6 pound rock tumbler from harbor freight that has been modified according to the skylighter website. My black powder works great but I can only get about a quarter pound out of every 5 hour run. I was looking around the internet and found a rock tumbler. It is called "Thumblers model B rock tumbler". I was just wondering if this would work for making bp. I know I will need way more media than I currently have but I was just wondering your thoughts and maybe if anyone actually uses this tumbler currently for bp production. Thanks.

[Mumbles]

This is a problem a lot of us run into eventually. Our pyro plans out compete our production rate. I know mine did.

 

Plenty of people use the Thumblers Model B. If you can find a high speed version, even better. They run at about the right RPM as is, so you don't need to modify them. Another similar mill is the Rebel 17, which is supposed to be a heavy duty version of the Model B. It has stronger rollers, powder coated jar, and stronger bearings. They're usually around $30 more expensive than a stock model B. The black jar wouldn't hurt to hide charcoal stains either.

 

Another option is a Sponnenburgh style mill, which are sold by a former pyro supplier. http://www.ebay.com/itm/15lb-Capacity-Rock-Tumbler-Heavy-Duty-Complete-with-Instructions-Made-in-USA-/351198743773?pt=LH_DefaultDomain_0&hash=item51c5138cdd I had one of these and loved it. I don't know about the model B, but you can place your Harbor Freight jars right on the frame and they spin at around the right speed, which I liked for milling small amounts of materials.

 

Either way any of the above will make good BP in 2-4hr.

 

One thing to note. The hexagonal jar of the model B/Rebel 17 have a lower critical speed than you will generally see recommended. The polygon shape seems to work much more efficiently than a round jar. Calculations will say you want a RPM around 75, but in reality about 40-50 is optimal. Just something to keep in mind if you get one. It may look too slow, but it's probably not.

[pyroman2498]

ahhh, ive run into this problem many time , I used the HBF mill you are talking about and it was good till I wanted more production , but I quickly joined a club( MAPAG ) and I haven't had to worry about milling , we have allot of commercial BP , and a 6 drum mill ( crazy , I know ! )

But the model B should work fine , it dosnt look like or seem like a bad mill , if you ever want to go bigger you could always build your own , there are allot people of knowledge with this , just have to ask around

 

Stay Safe and Stay Green

 

~Steven

[clarkie752]

Hey mumbles the link you gave me for the Sponnenburgh style mill looks nice and is a little cheaper than the model b. You said you had the Sponnenburgh mill..... Did you have to make any modifications to it to run at the right rpms? Also about how much media did you use to get good bp? The reason I was asking if the model b would work is because I could not find a weight capacity for it. I'm guessing with a barrel that large I would need 25-35 pounds of media for sufficient milling and I don't want to spend over 250 bucks for something that the motor is going to burn up on. It also would be nice to be able to do small batches of single chemicals in my mill jars from my harbor freight mill.

[Mumbles]

Other than using an extension cord, there were no modifications needed. I believe I also attached a felt furniture pad to the frame so the plastic didn't rub directly on the metal. My jar would occasionally drift/move ever so slightly. I used somewhere between 25 and 30 lbs of lead, which was about right. It's hard to judge exactly half full due to the geometry of the jar. I purchased my mill second-hand from another pyro, and easily milled over 100lbs of composition in the year and a half or so it was in use. It was at least 2 years old when I received it, so there wasn't any durability issues to be seen. I've never really heard any complaints from others with the same mill either. Everything is pretty open, so if you needed to replace a motor, it wouldn't be hard.

 

Very little maintainance. A wipe down occasionally, and oil on the shafts every so often kept it running great.

 

One downside is how the mill is constructed. It's a piece of PVC, with an end cap on one side and a 6" reducer on the other. This leaves a groove at the bottom for composition to get stuck in. This isn't really a problem if you're just making BP or similar compositions, but it can be a little hard to clean out if you wanted to switch to something else.

[clarkie752]

That sounds good mumbles. I only plan on using this tumbler for bp so the groove will not be a problem for me. Thanks for all the help and saving me about 100 bucks.

[PowderBurner]

First post.

 

I have a Frankford Arsenal Rotary Tumbler that I use for cleaning reloading brass (works great). It has a seven liter rubber lined drum, is direct drive and rated at 30 pounds capacity. The drum has a six sided design.

 

I thought I would try it out as a ball mill, so I cast up a large batch of .575" (58 cal) hard round lead balls. The trouble is that 30 pounds of lead balls only fills it to about 1/3 full.

 

I know that it is desirable to have the mill 1/2 full of media. Will I get acceptable efficiency with only 1/3 of the mill full of media? Should I try to find brass instead?

 

http://www.btibrands.com/product/platinum-series-rotary-tumbler-7l/

Edited April 1, 2015 by PowderBurner

[Shunt]

Any mill is better than no mill. Yes, you are undercharged with media. Run the mill longer if you have to, then cast up more lead balls as you can.

 

Mixing in brass media with lead will eat the lead balls as it is harder.

 

There are many posts on this forum that you can read, and gain more knowledge as to milling.

[schroedinger]

Powder you should add more media until you have a about 50 % of the jar filled.

 

If your mill has problems with the weight, you also can use:

Pieces of cut down brass rod

Non sparking stainless steel media (there are some suited types - make sure to ask about this before you buy anything)

Ceramic media either Alumina or Zyrconia are suited.

[PowderBurner]

Thanks for the Ideas guys.

 

 

"Any mill is better than no mill. Yes, you are undercharged with media."

 

 

Maybe I'll give it a test run. I can always regrind it later if it doesn't work out.

 

 

" Run the mill longer if you have to, then cast up more lead balls as you can."

 

 

I can't add anymore lead media, because I've maxed out the load capacity at 30#.

 

 

"Mixing in brass media with lead will eat the lead balls as it is harder."

 

 

Yeah I wouldn't run brass and lead together. The lead balls I cast have a hardness of 18 to 20 BNH, while 260 brass (cartridge brass) is about 140 BHN.

 

 

"There are many posts on this forum that you can read, and gain more knowledge as to milling."

 

 

Thanks. I have been and will continue to read, read, read......

 

 

"Powder you should add more media until you have a about 50 % of the jar filled.

If your mill has problems with the weight, you also can use:
Pieces of cut down brass rod

Non sparking stainless steel media (there are some suited types - make sure to ask about this before you buy anything)
Ceramic media either Alumina or Zyrconia are suited."

 

 

 

I'm researching the cost of 3.5 liters of brass balls or cut rod. So far the cheapest I have been able to find brass balls is about $0.50 per ball and it's going to take a lot of therm. The cut rod is a little cheaper at $8.00 per foot or about $0.35 per 1/2" piece.

 

Edited April 1, 2015 by PowderBurner

[calebkessinger]

I would just run it with the amount of balls you have and see where you are at. You might be surprised how well it still works without the (correct) amount .

 

Simple to test. run a 1 kilo batch of bp in it for 2 hours. pull enough out to press a spollette or to granulate, run for another 1 and take another sample. run for another hour and pull the whole batch..

 

I bet you find it works not so bad.. I ran my mill undercharged by 50 % for over a year , It still made great bp in 2 hours.

 

Everything doesn't have to be perfect. It just has to work. Yes perfect would be nice but.. Not everyone can afford or wants to put 500-1000 bucks into a ball mill !

[PowderBurner]

Sounds like good advice. I don't want to spend $300 on brass. I'll give it a try. Thanks!

[drdecibel]

I'm a newbie but am working on a DIY mill/tumbler project. I have posted it under "Brass Media".

how about taking a look at it and tell me what you think.

 

Thanks

[Filip85]

Hi, can anyone tell me what is the optimum diameter of jar for ball mill if I am using 200 steel balls for media? And how much RPM will be optimum for that jar?

[Filip85]

Steel balls are 12.7 mm

[mikeee]

Filip85,

 

Are the balls stainless steel?

[Filip85]

I think they are.

[schroedinger]

Filip the "I think" tells that you don't know which grade of steel you have. And because of that they are only suited for skngle chemical grinding. If you use them for bp you basically build a pipe bomb.

200 of those should be about right for a HF 3 lb barrel.

[Filip85]

I planned to use them for single chemical grinding. I dont want to risk with bp milling. If the diameter of jar is 90mm how much RPM I need for optimal milling?

[Mumbles]

This thread has formulas to calculate the optimal RPM in both imperial and metric units: http://www.amateurpyro.com/forums/topic/7604-ball-mill-rpm/

[Filip85]

Thanks

[Merlin]

So, is the MJR mill the way to go or the Thumbler Tumbler Rebel 17. Mostly concerned about replacing parts.

[calebkessinger]

The Rebel is what I've decided on.. Easy to work on, replacement parts available at the click of a button. Lightweight.

 

Factory motor is Junk, their is a couple options for a GOOD replacement.

 

Spins too slow... I make new rollers and pulley for it. The Rebel barrels are a little more true (smooth) than thumblers.

 

 

I have a rebuilt one here ready to go and a couple more on the way... The upgraded ones should last for years and years spinning a full load of 35 lbs lead at the correct speed. 66 rpm give or take a bit.

Edited July 13, 2015 by calebkessinger

[Arthur]

Many people have to trade off between size, speed, weight capacity and cost but still have a useful mill. Also it helps to have a small jar on the rack so that you din't have to mix 5kilos of a test batch. ALSO if you ever intend to use chlorates you DO need a separate mill and separate media.

 

If you weigh out a mill charge of all the required ingredients in advance, then running 2 - 4 mill batches a day should be easy. Ricing and drying could be another problem!

[starxplor]

The Rebel is what I've decided on.. Easy to work on, replacement parts available at the click of a button. Lightweight.

 

Factory motor is Junk, their is a couple options for a GOOD replacement.

 

Spins too slow... I make new rollers and pulley for it. The Rebel barrels are a little more true (smooth) than thumblers.

 

 

I have a rebuilt one here ready to go and a couple more on the way... The upgraded ones should last for years and years spinning a full load of 35 lbs lead at the correct speed. 66 rpm give or take a bit.

 

With all this replacement, why buy a mill and not make one from the ground up? I am preparing to get a mill myself because I don't want to do all it takes to build one, doesn't all this work negate the point of buying one?