Recommended small ball mill for BP?

[DrJones]

I'm familiar with best practices for mixing and milling BP. I note several very good ball mills are sold, yet every one is over $100. Two questions here:

Any particular brand name of ball mills available for $100, or less, or a bit more? I'm not into building a mill from scratch, so prefer one suitable to plug in and go.

Many smaller rock-tumbler "mills" have a round milling case, while other larger ones are usually multi-sided. I sense the multi-sided mill barrels are much better for BP milling, but has anyone had success with smaller, round-barrel mills?

I can easily run the mill for longer periods of time, if needed. Time isn't of the essence for me, though approaching Goex burn rates is what's wanted and needed, Skylighter promotes red-gum BP (unmilled) as being quite "hot," and I've had good results with that mode. Still, a ball mill will likely make "better" BP than any red-gum blend--I suspect.

Comments and ideas welcome. Thanks.

 

Edward in New Mexico

[mabuse00]

Dont go too small.

 

The milling process depends mostly on balls hitting each other, smashing the charge.

To get a good hitting power you'll either very heavy balls or a great falling height -> large drum diameter.

 

My barrels are some 12cm and I dont think you can go much smaller if you want a reasonably effective mill.

 

 

but has anyone had success with smaller, round-barrel mills?

Yes.

The right speed is important. if you get near the critical speed the balls start to get lifted up on the walls and come crashing down again.

 

 

I can easily run the mill for longer periods of time, if needed. Time isn't of the essence for me

Nevertheless you should try tro run your mill as effective as possible, let alone for wear of mill and media. Often the right setup makes the difference between the milling having very little effect to making very good BP in only 2 hours.

24h runs some people often mention is BS in my opinion, if it takes that long your doing something wrong.

 

 

Skylighter promotes red-gum BP (unmilled) as being quite "hot," and I've had good results with that mode.

That might work for you if the charcoal as it is delivered to you has allready gone through a ball milling or similar process and is of good quality/suitable for BP...

[Arthur]

Put 100 pyros in a room and you will get 200 different answers to your question.

 

For my 2p's worth, if you use a small hobby rock tumbler with ceramic media will give OK powder, the time you need will be determined partly by the preparation of the ingredients.

Lortone certainly do a 12 pound rock tumbler which is big and needs much media and ingredients. Typically a rock tumbler will not turn a full load of lead media and ingredients the motor and belt are not strong enough. I really like ceramic media.

[SharkWhisperer]

Skylighter's BP kits are complete crap, especially the "red gum" kit. Red gum has no role in pyro BP. The charcoal used in both (airfloat hardwood) is about the worst charcoal that you can use for making decent BP--you'd get equivalent (or better) performance from crushing up some lump bbq charcoal (not briquettes). And better results again making your own charcoal (even in a gallon paint can to learn). And if you compare Skylighter prices to essentially any other pyro chem source (fireworkscookbook, pyrochemsource to name a few), you'll see that you're often paying double the price for the exact same items. They are grossly overpriced. If you unfortunately bought one of the BP kits, you can use all of the ingredients, just not for decent BP. The charcoal is just fine for slow-burning star formulations. Crap for BP. Nitrate is fine. Sulfur is fine. Gum is fine (for fuel/binder in stars--not in BP). Just overpriced. Compare the total cost of a Skylighter "kit", either, to the same poundage of chems in that kit at FWC, and you'll see the Skylighter kit "savings" costs double what individual components usually cost.

 

It is not at all difficult to make BP that is much faster than Goex.

 

If you have the time, an 8 hour spin in an HF mill, with quality chems, will give you some very potent powder after wetting & granulation. It's not the most efficient mill for sure, but quite sufficient to get the job done for hobbyist-sized batches milling over a longer time frame than a more expensive unit that you might not be ready to commit to purchasing at this point.

[justvisiting]

This is the shape of mill jar that is most efficient. In my limited experience, mill jar diameter is more important than RPMs. A 4" diameter mill jar takes a long time, as others have pointed out. A 6 or 8" diameter jar of the same volume would do the job much faster and more completely.

[Piccaso]

The cheapest way to get into milling is to build your own. However mills and milling media are far from cheap.

This is the best mill jar I have found............

https://www.woodysrocks.com/store/p254/Rebel_Mill_Jar_.html#/

I use this mill I made the mods myself but if I where to do it again I would just buy one already done as I didn't save much.

https://www.woodysrocks.com/store/p352/Standard_Rebel_17lb_Mill_.html#/

This is a great deal on media on this site as well.

https://www.woodysrocks.com/store/c15/Ball_Milling.html#/

I would recommend saving your pennies and just buying one from here complete and ready to run with the mods done already, it will be your best friend in pyro and you will save yourself time and money screwing around with the small crappy mills as you will just end up here sooner or later if you are serious about this hobby.

Edited March 27, 2021 by Piccaso

[hanabi]

Here are some. I'm going to get a couple drums.

 

https://covington-engineering.com/tumblers/

 

https://www.therockshed.com/tumbler5.html#Large

 

http://www.diamondpacific.com/products.html

http://www.diamondpacific.com/Resources/2020%20catalog.pdf

[Arthur]

Have a look here https://www.therockshed.com/tumbler4.html Lots of tumblers from 3 pounds to 24 pounds (rock rating) I strongly prefer round rubber drums as they run extremely quietly. Most rock tumblers will not turn a full drum of lead balls but ceramic balls work fine. My mill holds about five pounds (rock rating) so it gets 2 kilos of balls and a kilo of mix. I leave it for 12 hours because that suits my work shifts but it runs so quietly that no-one notices the sound.

[Mitchell]

Hey there. Building a small milk myself. I wanted to ask. Why does everyone use belt driven instead of chain and sprocket? I don't see any more risk other than if something jams it's going to be much worse with chain rather than a belt slipping.

 

Am i missing something?

[Arthur]

Most people run cheap, belt and two rough pulleys are cheaper than two sprockets and some precision hardened chain. Plus for safety belts slip or flip off but chains must destroy something if the system fails.

[Mitchell]

That's what i figured. I was just asking because i have chain on hand as well as sprockets but just wanted to know if i was missing something. Thanks for the quick reply!

[BetICouldMake1]

I'll add that your ball mill will inevitably get dirty with mill dust and the nitrate will rust up any bare metal. To a lesser extent the metal rubbing on metal could be a spark hazard. I realize your running an electric motor, but still.

[Tanker6982]

Hey everyone I'm new here an also a noob to fireworks building, iv spent several years studying this stuff off an on. So I still dont know everything an never will. But my question for yall is! What's the best grinding media for charcoal? I'm guessing lead balls but can you use ceramic instead of lead? Iv pyrolysed my own hardwood for the first time, idk how well maple will perform but I'm aiming to find out. I just order a 3 pound ballmill from amazon, just need to know which media I need for hardwood.

And my next question is iv read that willow is the best wood to use! So kinda of a dumb question here but would that be a wheeping willow??

[Arthur]

Lead balls are good but heavy, and the powder made always contains lead, also if the drum is too heavy a cheap mill will not turn it over. Likely you will need to do some trials. a cheap rock tumbler works best with ceramic balls, a fully powered ball mill will work well with lead or brass media.

[justvisiting]

When I make BP that exceeds the performance of Goex apples to apples, I often use screen-mixed powders. The key is the charcoal and the milling method. I start with -10 or 12 mesh charcoal, and mill it with stainless steel media. Ceramic may be better for allowing a cheap mill to turn, but it's the least efficient of the common media types. I would never use lead for milling charcoal by itself, but for milling BP, hardened lead wears very slowly. Mill jar diameter is a huge factor. 4" diameter jars are the least efficient. Rock tumbling speed as opposed to optimal speed for BP is the least efficient way to get good BP. Extended mill times with complete BP are required, when the same mill can turn out better powder by milling the ingredients separately. 6" or greater diameter jars at optimal speeds make good BP in a very much shorter time.

 

Lots of woods make good BP charcoal. When I first heard that I needed willow to make good BP, I used narrowleaf willow. AFTER I made the BP, it was revealed that I had to use black willow. That information could have been revealed sooner, but no matter. My narrowleaf willow worked well. So did weeping willow, ERC, staghorn sumac, etc...

 

Somewhere around here I reported my results with various sizes of SS media from 3/16-1/2" diameter spheres, using a 4" diameter mill jar to mill the charcoal. The potassium nitrate grinds better with the larger 1/2" media. The sweet spot for charcoal in my rudimentary testing was 5/16" diameter. I used rubbermakers sulfur, so it didn't need milling. I'll see if I can find what I wrote.

[BetICouldMake1]

Lead balls are good but heavy, and the powder made always contains lead, also if the drum is too heavy a cheap mill will not turn it over. Likely you will need to do some trials. a cheap rock tumbler works best with ceramic balls, a fully powered ball mill will work well with lead or brass media.

 

I somewhat disagree. I ran lead in my little HF mill no problem. You can only run a single jar regardless, and the weight of the lead didn't cause any issues. Ceramic is lighter but for that reason also less efficient, like JV said. Since that little mill isn't very efficient to begin with I would go with lead. If you want to save a little weight and are willing to splurge you could run SS instead, but ceramic would be my last choice.

[justvisiting]

I found the thread where I tested small stainless steel media for super-milling charcoal to make good BP in a single component milling scenario, using a modified (for speed) Lortone rock tumbler. It's on Page 14 of the Ballmilling FAQ thread, in case anybody is interested.

 

"OK, I finally finished my little round of tests with supermilling the charcoal using a 3lb rock tumbler and 304 stainless steel media. The charcoal feedstock was 10-12 mesh, willow. I cooked it in a retort. As I have said before, my goal is to make black powder from separately-milled components. 50 grams of charcoal from the same batch was used for each test. Each batch was run with half a jar of stainless media for 6 hours. 45 grams of the charcoal from each batch was used to make 300 gram batches of 75-15-10 with pre-milled potassium nitrate. The charcoal, rubbermakers sulfur, and milled potassium nitrate were run twice through 40 mesh to combine.

Each batch was pucked, corned, graded to 2FA size, and tested. 10 grams of +1.8g/cc. grains were used for each test. Condiment cups contained the samples, which were fused with black match with visco leaders.

The tests were one-offs, and not conclusive. But, I think it's safe to conclude that newbies with rock tumblers can make GOOD black powder in small amounts, with minimum outlay. The pucking and corning is not necessary. It can be replaced by screen-granulating. In that case, the flight times would go up.

Here are the results from this round of tests:

3/8" SS media- 9.5 seconds flight time, 150 gram baseball in 3" ID mortar, 10.0 gram sample

5/16" media- 9.8 seconds

1/4" media- 9.3 seconds

3/16" media- 8.7 seconds

All these results are acceptable for lift, IMO. It is interesting that my favorite 5/16" size media seems to be the 'sweet spot' when milling charcoal in a small rubber jar. Of course, these one-off results are not conclusive, and will guide me in future experiments.

_____________________________________________________________________

Since then, I've come to realize:

1) Pressing to a density of 1.8g/cc. is over-kill, and makes the powder slower.

2) 2FA grade is needlessly coarse. Using 1Fg grade will give an extra second or more of flight time.

[OldMarine]

I'm late to this show but can still hope to help you avoid some future frustration.

Don't skimp on the mill. Save up and buy the biggest one you can afford.

[Dleipchack]

First posting.

 

I got into amateur pyro a couple years ago. I've been using a harbor freight mill to make black powder. I wanted to move up in size and had an idea to convert a treadmill into a barrel mill. We'll here is where I'm at with it. As a disclaimer, the jar in the pictures is not completed. It hasn't been glue yet. Just dry fitted. Here are the specs and details:

 

- rollers are original belt rollers that have bearings.

- rollers have a bike inner tube stretched over them for grip and a static barrier.

- utilizing the existing treadmill roller adjusters, the rollers can be spaced between 3" to 4 1/2" apart to accommodate 4", 5", or 6" jars.

- hardwired two momentary on/off/on toggle switches to control start/stop and speed.

- speed is adjustable in .10 mph increments from .5 to 12 mph.

- the motor's thermal override switch is still functional.

 

Here is a link to what it looks like

 

https://imgur.com/a/hAJ4v39

 

I'm looking for any advice, criticism, suggestions, etc. Is there any suggested improvements or words of caution.

 

Thanks

[Enpyroneer]

Dleipchack

 

Yours look quite heavy duty... I fancy building over buying as well, I`ve made over the years some 3-4 mills, the best ones so far, have been all direct drive. I like using windshield motors, they spin around 70rpm and have high torque.

 

Black powder only mill with hardwood lifters and lead media, rollers support https://imgur.com/PrFMO3v https://imgur.com/VFFp2dv

 

(MgAl) only mill with ''variable'' speed and using only double bearings https://imgur.com/DODhIHv