Finally got a ball mill, Tips?

[Arthur]

Most rock tumblers will stall if loaded with lead media. Look for ceramic (Alumina) balls the drum will turn when full.

 

https://www.inoxia.co.uk/products/ball-mill/media/ceramic-balls-20mm Will supply to USA, certainly the best supplier I know.

[nordicwolf]

Thanks for the supplier link!

 

About how many would be needed for a Rebel 17 jar?

 

Woody's has ceramic media but out of stock. I hope shipping across the pond is not too expensive...

[Arthur]

You'd have to message him for shipping costs and expect your country to apply import charges. Sometimes the only supplier simply isn't cheap. He might know how much is needed to fill a volume, measure the drum volume and message him

[nordicwolf]

Is there any advantage to cylindrical alumina media vs round media? One supplier suggests that "cylinder design will give optimal performance in grinding. Balls tend to roll when the cylinders will tumble causing shorter grinding sessions and better performance."

 

Thanks!

[nordicwolf]

Would these alumina spheres work for ball milling? They are advertised as a dessicant.

 

https://www.deltaadsorbents.com/activated-alumina-f-200-1-4/?attribute_pa_sizes=25-lb-pail

 

Thanks!

[justvisiting]

Those are no good. They are less dense than water and porous. I'd go with stainless steel spheres for general milling. For BP, I'd suggest you might go through the VERY laborious process of cutting brass rod stock to length and using that- the smaller the better. I'd use 1/2" diameter for a Rebel 17 jar. That would be 30+ pounds of media. You can tumble the burrs off before using it to mill BP. I used 5/8" and 3/4" diameters of the same lengths and deburred them one by one on a belt sander. They were too large, in my opinion, so I sold them cheap.

[nordicwolf]

Bummer, but thanks for checking that out. I am hoping to find a reasonably priced USA seller of 1/2" / 13mm alumina balls / spheres. This is not for BP but for other chems. I have lead already but it makes things gray like pot nitrate if I mill that solo.

 

Are stainless steel spheres safe? Are they a sparking hazard?

 

I have heard good things about alumina, hence my interest in finding that. If SS is a safe alternative for milling individual chems that might be easier to find.

[justvisiting]

Pyrocreations sells 1/2" ceramic cylinders for 6.98 for 50 pcs. That's .7lb of media they say. Stainless steel is about double the weight per load, so it's about 160 bucks for the ceramic media you need for 1 Rebel 17 jar at that price. I don't know if that's reasonable. I base my calculation on a load of 16 lbs. I see they also have chromed steel balls and would never think of using them myself for milling anything.

 

Stainless steel is probably as likely to spark as alumina media if used with BP. That's a guess. I'm not a scientist. People have concerns about both media, with not much but anecdotal evidence that either of them is more or less 'safe' available. I'd say milling BP should be assumed to be UNsafe under all conditions regardless of media, and any BP mill should be located and barricaded appropriately- just in case a rare accident should occur. That's the only time you need to worry about sparks with milling. You say you have lead media. There's hard lead media and soft lead spheres. Hardened lead wears very slowly when milling complete BP. I wouldn't worry about potassium nitrate being gray from lead contamination, myself. That's assuming you are using it for BP-type formulas. Milling charcoal by itself with lead wears it very rapidly though.

 

I'd prefer SS over alumina any day of the week, no matter what it would be used for. I do single component milling mostly. People use alumina because it's cheap, readily available, and light enough not to stall a very small mill. It's the least efficient media I've used.

[nordicwolf]

Where is a good source for Stainless Steel media?

 

I have a heavy duty motor and can handle lead media in the Rebel 17 jar no problem (made some pretty good BP with it). Pretty sure my lead is hardened. Interesting that it will wear down with charcoal.

 

I am headed toward single chem milling which would include charcoal, so does SS media wear rapidly if milling charcoal by itself? Thanks!

 

ps- the pot nitrate I milled could also be grey because of left over residue from the previous BP batch. I washed down the jar and media, but still there could have been cross contamination. I find that even after washing the lead media, it still leaves my fingers/gloves with residue I assume is BP and not lead (there is too much for it to be lead IMO.)

[justvisiting]

Woodysrocks.com supplied most of mine, but he seems to not carry them any more. Others were gifted to me, and some I purchased from Craig Ball sales. I see now that they have 13mm 304 SS balls for 55.00 for 50. Slightly smaller 316 SS balls are much cheaper per ball. The 15/32 balls are 25.00/50pcs and the 11mm balls are 18.00/50pcs. I haven't shopped extensively. Better prices may be available somewhere else. Craig Ball service was very good. They shipped my order to Canada even before I paid for it!

 

Charcoal alone wears lead media rapidly because the media just falls right through it easily and wears on itself, just as it would in an undercharged mill. SS media doesn't wear to any perceptible degree when milling charcoal or any other pyro chem. The smaller media mills the charcoal to a finer powder. SS media is expensive, but it lasts forever and is corrosion resistant. If you could only buy one size, I'd go for the 15/32" for a 'one size fits all' media size in SS. The media I have is 304, but 316 is supposed to be more corrosion resistant. The SS media that I was gifted is 5/16" diameter, and mills charcoal to an impalpable powder. Most folks wouldn't bother to do such a deep dive on the subjects of BP and milling, but I found the generally accepted lore to be light on empirical data, so I got curious enough to learn a bit more.

 

I only use lead media for BP, so I never clean it.

 

I did quite a few experiments with BP milling and single component milling. I posted my results on Pyrobin but that site is down now. If you want to PM me an email address, I could send the files to you.

[cmjlab]

JustVisiting,

 

At risk of being hollered at for unsafe milling practices, but I'd rather know now if it is unsafe....

 

Why not use cheaper chrome steel balls for milling single chemicals? **NOT milling B.P. or other combined chemicals, SINGLE chemical milling only**

 

They DO require extra maintenance (must be cleaned and dried after use, before being put away to avoid corrosion) but are far CHEAPER than stainless steel milling media, and can be purchased off Amazon here in the U.S. for ~$16.00 (U.S.)

 

Again for milling B.P. I only use Lead Media, mainly because I can't afford the brass or stainless steel costs.

 

Thanks, Charles

 

*Edit* I should also add that I have the space and distance to place my ballmill far from any other structures or property, and I always plan for something to go wrong when milling.

Edited September 23, 2022 by cmjlab

[justvisiting]

cmjlab, I bought cheap plated balls and the plating flaked off. Also, I once forgot plated media in a mill jar with potassium nitrate (only) and it was attacked and rusted. Those experiences turned me off. Knowing that I'd be likely to make the same mistake again, I decided to save myself from myself To be fair, the media was probably poor quality seconds, knowing the vendor as I (now) do. I had an issue with his alumina media as well. He's now passed on, so no need to say who it was.

 

Everybody (including me) agrees that hardened lead is the best media for milling BP. It can't spark, and it's the most efficient. Ceramic media and SS media both have the potential ability to spark, although I've used both to mill BP, as many others have. I barricade my remotely located mill as well, as everybody should when milling live BP. I'm not suggesting that anybody mills complete BP with SS media, because I don't want to get hollered at either I'm just saying I don't think alumina is any 'safer'- and I've used ceramic a lot. As soon as I switched out the alumina, my BP improved. I used my alumina spheres to mill charcoal by itself, and also to mill BP. After a long time, I noticed that the surfaces of the media had developed 'craters' from the repeated impacts. I was concerned about the degrading media forming grit that could cause an ignition, and stopped using it out of an abundance of caution.

[cmjlab]

Thanks for the follow-up / info. I just wanted to make sure I wasn't doing something really stupid, it works great for quick milling of individual oxidizers, just charcoal and just Mg/Al (which I realize brings a whole other set of dangers).

 

I'm certainly not challenging the well validated safety of lead, and am not in a position to argue for using stainless media when milling B.P. either, especially since lead works great, though most people I've heard from would use it if they could afford it (taking all safety precautions of course).

 

I use the plated media for single chemical milling, mainly because it's cheaper than purchasing stainless media, and is really effective. Plus, I don't have to clean my lead media since it's only used on B.P. I have not yet left the plated media in the mill jar, but I can see me working late one day and telling myself I'll get it first thing the next day.... (And that set of media would be left for no less than a week if I know myself and converted to iron oxide in a most unusable form!).

 

Charles

[cmjlab]

Tip (from one cheap newbie to another)..... Save money by building your own ball mill, but just buy the Rebel Ballmill Jars from pyrocreations.com.

 

I pieced together a working ball mill based on odds and ends I had laying around, and made sure it was optimized for a ~6" Jar (somewhere around 59/60 RPM. I only bought pillow bearings new, but used spare parts for the rest.

 

For the Jar I followed other people's lead and made a PVC mill jar, but ultimately spent at least $70-$80 on the jar. It finally broke, and I was tired of the pain in the butt of opening / closing / dealing with the jar everytime. So I bought the Rebel mill jar and holy easy day!

 

It mills nicely, it opens / closes nicely, and doesn't need tape to make sure it doesn't leak! It actually mills more efficiently without the lifter bars that my other jar had.

 

If anyone is like me though, your first mill jar will be a PVC anyway because like me, you will think you can build it cheaper..... And maybe you can, but it still won't be as easy as using the Rebel mill jar. So if or when the PVC breaks, buy yourself one!

Charles

Edited October 14, 2022 by cmjlab

[Powderman]

Justvisiting,

 

I would like to supermill my blender-pulverized charcoal. As I understand it, I dont´t need big balls for fine stuff. I asked one seller on Aliexpress and got price on 304 9mm 500pcs SS balls for USD 45. Would it be suitable for at least medium efficient milling? I am considering 132mm inside diameter for the jar and width 100mm. I guess I need 1000 balls?

[cmjlab]

Powderman,

 

JustVisiting is certainly the expert, but if you don't plan to mill complete B.P. mix, and single chemicals only, the chrome steel balls on Amazon work well too at 1/2".

 

Charles

[Powderman]

In the meantime I already bought the SS balls, 9mm/1000pcs for 105€ including VAT and delivery seems to be a good deal here in EU... I am not sure If I could save much buying lower grade media, at least what I have found was all pricey... And big packs of steel slingshot ammo are sold out in all shops here, maybe it would work for charcoal but I lost patience :-)

[cmjlab]

Well as JustVisiting said the best media for what he suggests is similar to what you purchased, so I'd say that's a good start. I tried to find affordable SS media in 300 series for B.P. milling (though admittedly poses higher risk), but I couldn't find it for less than $0.75 - $1.00+ / per ball. Too rich for my wallet, so I use lead for B.P. and Chrome (slingshot ammo) for single component milling. It is a Pain In The Ass to wash / dry / inspect for each mill run though, so eventually I will buy the SS.

 

Charles

[Powderman]

If it helps someone this is where I made my purchase:

www.aliexpress.com/item/1005003388520510.html

I have contacted the seller and asked him to give me a price for 9mm ball 1000pcs. It was $85 including shipping but without VAT. I will share my experience when it gets here.

[cmjlab]

Appreciate it, and yeah - if you don't mind,let me know how it goes. I've heard that due to shipping backlog issues and other geopolitical issues, purchasing items from China for delivery to the U.S. doesn't always go so well (especially more recently).

 

Charles

[Phil]

Been away from the forum and this hobby for a while now. I went and splurged five whole dollars on a 2lb sack of clear glass marbles the other day to get my mill up and running that I bought and forgot about. I only intend on using that for charcoal for obvious safety reasons. I 100 mesh screen mixed with my milled ERC (30-45 minutes) and did a test burn. It's certainly an upgrade than what I got with the hardwood airfloat. I'm out of rocket tubes but the results look promising, it'll probably be even better after granulation. Anyone ever use glass marbles? Do they chip/break? Iridescent Clear Glass Marble Filler | Hobby Lobby | 3505

 

 

Edited November 13, 2022 by Phil

[cmjlab]

When I first started I tried marbles, but it was not very efficient, and the marbles quickly wore down to half their size, which meant I was getting a decent amount of glass in my milled chemicals. So I switched to lead milling media, and later to stainless steel 304, with remote and barricaded milling.

 

Edit: The marbles started as 1/2" and within 4/5 months could pass through a 4 mesh screen (less than 1/4"), I think I still have them, I'll see if I can find them and post a photo.

 

I know you are probably aware, but even if you mill single components you will get glass dust in the individual component. When you screen it together with other components (i.e. black powder, etc) you're introducing glass into any complete comp you make. Glass is a sensitizer which *edit* significantly increases the friction (and probably impact) sensitivity.

 

Stay safe!

Charles

Edited November 14, 2022 by cmjlab

[Phil]

Yeah I figured the glass contamination may have been an issue in the longer run. I suppose that'll be a good thing if I ever want to DIY firearm primers lol. I've seen a few videos on that but that's a different adventure entirely.

 

I went to academy the other day and bought some of those 50 cal muzzleloading balls, I know this isn't ideal given it isn't hardened but it's probably good enough for me given I just intend on doing about 50 rockets a year. I still haven't been able to put my new screen mix powder in a motor since I'm out of tubes so this is probably overkill anyway. I put them in my clean mill jar since my tumbler came with two of them. I cleaned out the firepit out back and tried reinforcing it a bit in the direction of civilization. I got a long extension cord I can run out there. It'll probably take some effort getting it balanced, my mill jar wanted to walk to one end of the machine in the place it was before and that was pretty flat.

Edited November 16, 2022 by Phil

[Arthur]

Why do you think that match compositions (match that lights cigarettes) and primer compositions contain "ground glass" as a sensitiser while we wouldn't want a sensitiser in BP.?

[Phil]

I'd say with something like match heads and primers you want something that's sensitive to friction and impact otherwise it'd be useless. We only like our BP being activated by fire.

 

Anyway I got the mill running right now, I had a quite a hard time getting it level and the jar is still walking around and scraping the sides but at least it's a safer configuration. Also had to tape my clear tubing to the shaft because it was spinning freely. Would it be easier just to modify the mill again by putting those little sliding door rollers on there?

 

I'll be doing a short run today on the count of it's getting damn cold outside, it's getting dark and I've got some quirks to work out with the mill jar moving.

Edited November 16, 2022 by Phil