Finally got a ball mill, Tips?

[Phil]

After a few years of screwing around and making weak BP I was able to get one of those dual drum rotary tumblers locally from a harbor freight. https://www.harborfreight.com/dual-drum-rotary-rock-tumbler-67632.html

 

Few questions.

 

I haven't got the media yet. Looking to get it rather cheap. Will this be sufficient for making BP with? https://www.ebay.com/itm/193973924808?var=494153660758

The manual says to lubricate the bearings before first use and regularly. What type of oil do I use? All I have on hand is wd-40 and silicone lube which I'm thinking neither is ideal.

Are there any modifications I need to make to this for it to work for my purpose or is it good to go out of the box? Any thing that's not necessarily required but will make it better?

[justvisiting]

Others may disagree with me on this, but if they do, they may feel that I'm wrong, without knowing from experience. It's not rude (in my opinion;) to ask for data. You are better off to do separate component milling with one of those cheap mills. The small mills require extra milling time to make good powder. That extra milling time is a safety concern if milling live powder in an area that has people nearby. When milling the components singly, the mills can be left overnight or throughout the day without fear of accidental ignition.

 

IF you choose the single component milling route, you will want to speed up the mill to reduce run time. It's commonly done by increasing the diameter of the rods with heater hose or something similar. I think the ideal speed for such a mill is 92 RPM, but mine runs at around 75 RPM. The only way you can use both jars is with ceramic media, the cheapest (and least efficient) choice. If you do use the single component or double component method, stainless steel is your ideal media choice. Brass would be a little better because it's non-sparking, but try to find it cheaply! If you are married to the idea of milling complete powder, you can do the single component milling first, and then finish with an hour of milling using the soft lead you linked to. If you use soft lead for single component milling, the wear will be significant. Woodysrocks.com sells hardened lead and stainless steel media. I use 3 in 1 oil on my Lortone 'mill'.

 

If you overload the mill you will make weak powder, and extended mill times are needed to make it better, often 12 hours or more. This article from Pyrobin might be helpful in answering some of your questions:

 

http://pyrobin.com/files/Black%20Powder%20six%20ways%20V.2.pdf

 

EDIT: I've since found that reducing the hard sulfur discs in a blade mill (coffee mill) is far faster and better than ball milling it.

Edited June 14, 2021 by justvisiting

[SharkWhisperer]

After a few years of screwing around and making weak BP I was able to get one of those dual drum rotary tumblers locally from a harbor freight. https://www.harborfreight.com/dual-drum-rotary-rock-tumbler-67632.html

 

Few questions.

 

I haven't got the media yet. Looking to get it rather cheap. Will this be sufficient for making BP with? https://www.ebay.com/itm/193973924808?var=494153660758

The manual says to lubricate the bearings before first use and regularly. What type of oil do I use? All I have on hand is wd-40 and silicone lube which I'm thinking neither is ideal.

Are there any modifications I need to make to this for it to work for my purpose or is it good to go out of the box? Any thing that's not necessarily required but will make it better?

You can probably buy that unhardened .49 lead ammo domestically for cheaper than that. Even with shipping costs.

 

As JV said, you will not be able to run both jars on that mill with a half-jar of media that is standard. You can only run one jar at a time, and it will use around 75 of those balls. The stock mill runs at around 60 rpm. 90 rpm is ideal for that diameter jar. Easily done by cutting a section of vinyl tubing (Home Depot etc, a buck or two), splitting it with a knife, and sliding it over the drive rod. No glue necessary if you size it right. If you have issues, then pm me and I'll dig mine out of a box and check the tubing sizing. I'm sure it's specified on another thread here.

 

JV's suggestion to single-mill components is prudent, but I started out with the same mill and (anecdotally) have milled over a hundred pounds of complete BP on one of those without incident. Lead works much better than the marbles I started out with long ago, but you could run both jars. About 175g/jar of comp is your max load, 200g would be pushing it.

 

Though some think SS is the best media, I'd go with antimony-hardened lead for maximum density balanced with hardness. Pure lead balls will definitely shed some lead into your comps. If you mill white KNO₃, it'll come out light grey with pure lead. If that bothers you, then that's also prudent and go with something else.

 

Lubrication of the rod ends is just 3-in-one Household oil or any silicone oil. Do so every few runs, don't overload your motor, and those crappy Chicom motors might last you for years. My first HF mill came with 4 or 5 extra rubber drive belts and I never changed one before it got retired after probably 300 hours of use. I probably lubed it 5 or 6 times. The rod ends tend to accumulate junk in them, and it might be helpful to simply wipe it off before lubricating.

 

If your components or comps clump in the mill, it is because they are damp. Period. KNO3 and charcoal get oven-dried before milling always. Especially charcoal. That shit's a friggin sponge that'll suck atmospheric water big time. I've measured 20% water weight in charcoal that seemed completely dry to the touch--others have reported 50% and I believe them. Once oven dried, I store mine airtight with silica bead packets to absorb moisture.

 

Can't comment on milling sulfur "discs" mentioned earlier because I've never seen them; my sulfur's always been pure n powder and never needed drying (it's not hygroscopic) or pre-milling.

 

I had no qualms about going to bed with a mill running outside my back door with a load of comps and shutting it off after my morning coffee... But everybody's got different tolerances.

 

Always best to operate on the side of caution.

 

If you were hand-mixing BP before, you will be amazed at the quality of what emerges from your new mill.

[Carbon796]

 

JV's suggestion to single-mill components is prudent, but I started out with the same mill and (anecdotally) have milled over a hundred pounds of complete BP on one of those without incident. Lead works much better than the marbles I started out with long ago, but you could run both jars. About 175g/jar of comp is your max load, 200g would be pushing it.

Do not follow Shitwhisper's use of glass marbles/media. They've been attributed to at least one mill explosion. His information is usually incomplete and misleading.

[SharkWhisperer]

Do not follow Shitwhisper's use of glass marbles/media. They've been attributed to at least one mill explosion. His information is usually incomplete and misleading.

That was not advice, that was personal experience. Provide, please, a link to one single marble media-caused BP milling explosion. Lotsa luck. They don't exist.

 

IF, and this is not a recommendation, you use glass marbles (they're low-density media) for milling energetic comps, use only transparent clear glass marbles. Colored marbles possibly contain metallic pigments that may cause sparks by friction. Though I know nobody that has ever demonstrated this.

 

Personal experience supports the low risk. That is not a recommendation to mill with glass. Glass milling is inefficient. I do not use or recommend glass for milling media. However, I would love to see one, just one, verifiable report of glass marbles causing a pyro disaster or the simplest of injury.

 

Without references, our geriatric pal Carbon is simply repeating a story that he heard from a friend of a friend of a friend....ad nauseum.

 

Educate us.

 

Use hardened lead or stainless steel media only for milling flammable comps. They work best and are a long-term solution. Simples.

Edited June 15, 2021 by SharkWhisperer

[justvisiting]

I hate to say, but there was 'just one' accident attributed to milling BP with glass marbles. A fellow named BurritoBandito or similar had milled a batch of BP in a (rubber?) jar, and rapped the jar for some reason before opening it. His hand was mangled by it when it went off. A pyro guru accused him of faking the accident for some reason. The injured fellow's account seemed genuine to me.

[Arthur]

There was a picture and text thread on this forum about 4 years ago, the thread was do not mill with marbles, the picture was a hand with a finger missing and about a hundred stitches. The poster was the person who milled with marbles and lost half his hand.

 

https://www.amateurpyro.com/forums/uploads/monthly_07_2014/post-18033-0-54838900-1404863752.jpg

 

Marbles shed microscopic flakes of glass that sensitise the milling powder, this time it was so sensitive that it exploded in the mill. Try holding down a decent job with a hand like that, try affording the hospital or even the copay costs with no job.

[SharkWhisperer]

I hate to say, but there was 'just one' accident attributed to milling BP with glass marbles. A fellow named BurritoBandito or similar had milled a batch of BP in a (rubber?) jar, and rapped the jar for some reason before opening it. His hand was mangled by it when it went off. A pyro guru accused him of faking the accident for some reason. The injured fellow's account seemed genuine to me.

Thanks JV. What's the link to his post or any other source of info? He's become a ghost.

 

Arthur's pic without a link means little. With all respect, claims that are unsubstantiated are questionable.

 

I iterate my experiences and clear lack of recommendation.

[SharkWhisperer]

There was a picture and text thread on this forum about 4 years ago, the thread was do not mill with marbles, the picture was a hand with a finger missing and about a hundred stitches. The poster was the person who milled with marbles and lost half his hand.

 

https://www.amateurpyro.com/forums/uploads/monthly_07_2014/post-18033-0-54838900-1404863752.jpg

 

Marbles shed microscopic flakes of glass that sensitise the milling powder, this time it was so sensitive that it exploded in the mill. Try holding down a decent job with a hand like that, try affording the hospital or even the copay costs with no job.

Aw hell, Arthur, you're a smart dude. Where's the chatter that goes along with the pic you posted? And what is the mechanism that you propose by which glass shards "sensitize" BP? You know physics, electricity, and chemistry. Dangerous "sensitizing" glass shards? That requires a bit more explanation.

 

Full disclosure for full evaluation.

 

I don't recommend using glass marbles for milling BP (mostly because they're inefficient), but will view such cautions to be of questionable merit unless somebody can provide more details than a pic of a bloody hand with no accompanying information (and a questionable backstory where it even then apparently wasn't believed to be true..).

 

Then we can compare the ratio of glass- vs lead-related BP milling misadventures.

 

There's not a huge risk with conscientiously milling BP unless you open the jar with a lit cigar hanging out of your maw.

Edited June 15, 2021 by SharkWhisperer

[Phil]

I have some sandbags and concrete blocks just sitting around so I figure it wouldn't be a bad idea to put them to use as a barricade so I can run the mill in the backyard. This is another option for media as suggested above. https://www.midsouthshooterssupply.com/item/000036093/point495-diameter-182-grain-lead-round-balls-100-count

 

I intend on mainly milling BP with lead but I got a lot of ERC to convert to charcoal then process so I figured that would be the single component milling I'd be interested in. I'll be sure to stay away from the marbles and ceramic media. Stainless steel for single components only. I suppose the small capacity of this mill won't bother too much since I was already making small batches due to my small screens I bought that prevent me from fitting my hand in to easily pass the powder through. I'll probably head to lowes tomorrow to get the oil and vinyl tubing. I assume it's gonna be 1/2"? Appreciate the input guys.

[SharkWhisperer]

I have some sandbags and concrete blocks just sitting around so I figure it wouldn't be a bad idea to put them to use as a barricade so I can run the mill in the backyard. This is another option for media as suggested above. https://www.midsouthshooterssupply.com/item/000036093/point495-diameter-182-grain-lead-round-balls-100-count

 

I intend on mainly milling BP with lead but I got a lot of ERC to convert to charcoal then process so I figured that would be the single component milling I'd be interested in. I'll be sure to stay away from the marbles and ceramic media. Stainless steel for single components only. I suppose the small capacity of this mill won't bother too much since I was already making small batches due to my small screens I bought that prevent me from fitting my hand in to easily pass the powder through. I'll probably head to lowes tomorrow to get the oil and vinyl tubing. I assume it's gonna be 1/2"? Appreciate the input guys.

Ah sheesh. Ya couldn't measure your rod and do the math to get the rpm conversions, huh? So I had to go out to my garage to find my old roll of vinyl tubing that I used on my HF mill, is it?

 

Alrighty then. Yes, it's 1/2" ID. And 3/4" OD. It'll make her run 90 rpm where you want it. Don't guess. Clear vinyl.

 

Just giving you a little grief. Glad you're set up and rolling. Have fun and stay attentive. Taking notes is often helpful, too.

[BetICouldMake1]

It is generally accepted that milling with marbles is unwise. They can spark. They are made of a totally unknown and unverifiable material. They can deposit shards of glass into your bp. If nothing else those shards of glass can then deposit themselves into your fingertips.

 

It is also generally accepted that one man's anecdotal evidence does not constitute law. People have milled bp will all sorts of stupid shit without blowing up a mill. That doesn't mean it's a good idea, or safe.

 

5lbs of proper media is cheap. Medical bills are not.

 

Everyone is entitled to assess their own level of acceptable risk, but as a community I see no reason to endorse unnecessarily dangerous practices.

[justvisiting]

https://www.amateurpyro.com/forums/topic/9798-ball-mill-explosion/

 

This is the accident I was referring to. There are 14 pages of discussion about it. I don't remember the exact details, and didn't read it all over again. I'll just say that the guru that accused Burrito Bandito of lying about his accident made the same accusation about a different accident, and I didn't think the other guy was lying either. Folks can read the thread and draw their own conclusions about the accident. I wish BB was still around here, I'd love to talk to him about his avatar

[Arthur]

Like a lot of things there seem to be no immediate witnesses to BurritoBandit's incident, he had no reason to lie, he's the one who has to use that hand for the rest of his life.

 

It's a well known fact in HE that grit and particles of powder can sensitise explosives, I see no reason not to make a connection to BP dust.

 

The big reason to work to best available standards is to minimise the risk of accidental explosions with the hurt and media attention and Law enforcement attention.

 

However non believers can chose to play pyro by trial and error if they can afford the costs.

[Phil]

Got the 1/2 x 3/4 vinyl tubing over the drive shaft and it seems to be going about 85-90 rpm as desired. Great idea! The tubing seems to be "belled" out on the sides though and I think this may be causing it to run a bit "bumpy". Is this anything to worry about, can it be relaxed with a heat gun?

[Carbon796]

That was not advice, that was personal experience. Provide, please, a link to one single marble media-caused BP milling explosion. Lotsa luck. They don't exist.

Love your continued willingness, to prove yourself inept.

 

Edward Jones in Socorro, NM. Is a more reliable choice, for accurate information. Than you are, at this point in time.

Edited June 16, 2021 by Carbon796

[SharkWhisperer]

Love your continued willingness, to prove yourself inept.

 

Edward Jones in Socorro, NM. Is a more reliable choice, for accurate information. Than you are, at this point in time.

Ya just can't stop, ya old curmudgeon, can ya? That's fine. Still with the extra commas, is it? And the inappropriate period after "NM". How many times did you repeat high school English, if you made it that far?

[SharkWhisperer]

Got the 1/2 x 3/4 vinyl tubing over the drive shaft and it seems to be going about 85-90 rpm as desired. Great idea! The tubing seems to be "belled" out on the sides though and I think this may be causing it to run a bit "bumpy". Is this anything to worry about, can it be relaxed with a heat gun?

Good on you. Unsure if vinyl is heat-pliable. Try it. It should straighten out with use--mine came in a roll with the same issue but fixed itself pretty quickly spinning heavy jars. Or you could use some electrical or duct tape to make it behave. I didn't bother taking off the rod--just cut the tube down the middle and slipped it over and it stayed that way for years without moving. No glue. No tape. The fit was pretty good. At your recorded speeds you'll get optimal milling efficiency from the 4" jars that come with it. Don't overload it to the point that it bogs down or that inexpensive Chicom motor could easily be overstrained. Small bumpiness probably not an issue so long as the mill is not operating near it's limit and being transmitted back to the motor and making it work harder.

[SharkWhisperer]

https://www.amateurpyro.com/forums/topic/9798-ball-mill-explosion/

 

This is the accident I was referring to. There are 14 pages of discussion about it. I don't remember the exact details, and didn't read it all over again. I'll just say that the guru that accused Burrito Bandito of lying about his accident made the same accusation about a different accident, and I didn't think the other guy was lying either. Folks can read the thread and draw their own conclusions about the accident. I wish BB was still around here, I'd love to talk to him about his avatar

Ahhh, there it is. Good info for folks new to milling, and pyro in general.

 

As are BetICould's statements that:

 

"5lbs of proper media is cheap. Medical bills are not." and:

 

"Everyone is entitled to assess their own level of acceptable risk, but as a community I see no reason to endorse unnecessarily dangerous practices."

 

Operate on the cautious side. This hobby is all about risk management.

Edited June 16, 2021 by SharkWhisperer

[Uarbor]

I have been using the Harbor Freight style Mill for about a month-and-a-half now. I have been using lead antimony media. I did the modifications to increase the speed of the jar. It has been making great black powder for me. Skylighter has an excellent article about how much composition to put in the Mill at one time I believe it's 125 G plus 5 lb of lead balls. The jars that came with mine started to deteriorate and I got some extra jars. I got tired of taking all day to make a pound of powder with three Hour Mill runs and 125 grams at a time. I checked around the barn and I had almost everything I needed to make a bigger Mill. The only thing I had to order was the 10 inch pulley for $17 I whipped this together in about an hour and a half this morning. I already had a large number of 50 caliber Muzzleloader balls so I can spin four jars and 20 lb of media now check it out. Obviously I will get a real mill jar someday but this will do for now I have quadrupled my capacity

 

https://youtu.be/ZVa9bTnw2JU

Edited June 17, 2021 by Uarbor

[Uarbor]

I have some sandbags and concrete blocks just sitting around so I figure it wouldn't be a bad idea to put them to use as a barricade so I can run the mill in the backyard. This is another option for media as suggested above. https://www.midsouthshooterssupply.com/item/000036093/point495-diameter-182-grain-lead-round-balls-100-count

 

I intend on mainly milling BP with lead but I got a lot of ERC to convert to charcoal then process so I figured that would be the single component milling I'd be interested in. I'll be sure to stay away from the marbles and ceramic media. Stainless steel for single components only. I suppose the small capacity of this mill won't bother too much since I was already making small batches due to my small screens I bought that prevent me from fitting my hand in to easily pass the powder through. I'll probably head to lowes tomorrow to get the oil and vinyl tubing. I assume it's gonna be 1/2"? Appreciate the input guys.

I got my tubing from advanced Auto Parts its more rubbery and grippy and durable because it is reinforced black rubber. I don't know if anyone mentioned it but it's a great idea to have a timer to shut off your Mill it will give you better consistency Edited June 17, 2021 by Uarbor

[SharkWhisperer]

I have been using the Harbor Freight style Mill for about a month-and-a-half now. I have been using lead antimony media. I did the modifications to increase the speed of the jar. It has been making great black powder for me. Skylighter has an excellent article about how much composition to put in the Mill at one time I believe it's 125 G plus 5 lb of lead balls. The jars that came with mine started to deteriorate and I got some extra jars. I got tired of taking all day to make a pound of powder with three Hour Mill runs and 125 grams at a time. I checked around the barn and I had almost everything I needed to make a bigger Mill. The only thing I had to order was the 10 inch pulley for $17 I whipped this together in about an hour and a half this morning. I already had a large number of 50 caliber Muzzleloader balls so I can spin four jars and 20 lb of media now check it out. Obviously I will get a real mill jar someday but this will do for now I have quadrupled my capacity

 

https://youtu.be/ZVa9bTnw2JU

Nice workaround!

[ThaDawg]

Sorry for the bump i'm not able to start a new topic.. is there someone who can help me calculate the pulley size for my ball mill?

[SharkWhisperer]

Sorry for the bump i'm not able to start a new topic.. is there someone who can help me calculate the pulley size for my ball mill?

You can start a new topic now; you just needed to have at least a first posting, which you now have. Welcome to APC.

 

If you know your motor shaft diameter and rpms, it's a simple proportional formula to calculate driven pulley rpms for any given size. D1N1=D2N2, where D1 is motor drive shaft (or disc/pulley) diameter, N1 is number of RPMs of motor shaft/pulley, D2 is driven pulley diameter, and N2 is driven pulley rpms. It's a pretty easy hand calculation, but there are online calculators available. Here's one at: https://www.engineeringtoolbox.com/pulley-diameters-speeds-d_1620.html This particular calculator can calculate up to 4 connected pulleys. You'll only be using 2, so just put in the 3 known values (motor shaft diameter & speed, and desired final RPM) and it'll calculate the size of the final/driven pulley diameter that you want. Just ignore the remaining 2 pulleys on this calculator.

 

Desired final RPMs depend on planned container diameter to get optimal milling efficiency. There are several threads here by people who have made homemade ballmills, with detailed instructions that you can follow or use as a template to start from and modify. Lloyd Sponenberg has a book circulating on the topic that's pretty in depth. So you shouldn't have too much trouble locating answers to your questions.

 

If you aren't able to easily find the information that you want with a thread search, then just start up a new thread and folks will help with any specific questions you might have. The more detailed your questions, the easier it will be for others to give you a useful answer.

 

Have fun!

[Viper9399]

I use this media in my ball mill works great.

1/2-Inch Hardened Lead Ball Milling Media — Skylighter, Inc.