8 replies to this topic

[wymanthescienceman]

Hi everyone!

 

I've recently started getting into pyrotechnics again and was working on my ball mill jars when it hit me, instead of building them from PVC parts which end up costing around $10-$25 each for parts alone, how well would a large stainless steel water bottle work? I've been perusing Amazon and noticed that half gallon and one gallon size water bottle are relatively inexpensive, often under $20 shipped in the US. JB Weld/Epoxy in some lifter bars on the inside and voila, air/water tight mill jar for very little work, and cheap to boot. Is there something I'm missing here as to why these couldn't/shouldn't be used?

 

304 series stainless should be non sparking even if you wanted to mill BP, would be anti static, durable and easy to clean. Even if you didn't feel safe milling BP in them they would be great for single chems and inert comps. Bonus points they come in many colors for easy identification. There are multiple varieties and sizes to pick from, the wide mouth ones seeming to be the best bet.

 

Example bottle is 64oz and is currently $16.25, it costs me about $10+ at my "local" hardware store plus an hour or so of time just to make a single half gallon jar. Gallon size is more like $20+

 

Thoughts? What am I missing here?

 

[Richtee]

Fugger’s gonna be LOUD. MIGHT end up stress cracked. If something goes south it’ll be an effective grenade. And... sure it won’t spark?

[Arthur]

Most people regard noise as the No. 1 enemy with DIY mills, I suspect that this would be very noisy.

[wymanthescienceman]

Not like a PVC jar full of lead balls exploding isn't any less dangerous, at least the stainless would split versus fragmenting most likely. And as I said even using them for single chemical milling would be great. Even still I could have sworn stainless steel has been used by others as mill media, and what would possibly cause a spark using lead media as most people do?

So y'all just think it would be too loud? In a decent enclosed mill wouldn't imagine it to be that much louder than my PVC jar, that thing is pretty loud already. And being loud doesn't sound like a deal breaker to me anyway, the mill is in the garage and unless you're living in an apartment (which if you're doing pyro you really shouldn't be) I can't see being loud to be an issue, it can be mitigated. Are there potentially any other risks?

I'm going to have to experiment then, I'll have to order one and we are going to find out how loud it ends up being, and any other flaws it may happen to have. I do kind of wonder about the stress cracking, only one way to find out!

[wymanthescienceman]

Well I got one of these stainless water bottles from Amazon to test, only cost $16. It has a nice large opening and the inside is kind of a frosty texture, nice for epoxy to adhere to. So I went ahead and JB welded a couple PVC lifter bars in, removed the handle from the lid and cut down the nubs, and added some zirconia ceramic media to test and see how loud it was. I set my phone about 2 feet away from my mill and used a sound meter app to get an approximate decibel reading (not super scientific I know). My mill is enclosed and the lid was shut.

I ran 2 tests for 30 seconds, one test with my old PVC jar and one with the new stainless jar. The average reading over the 30s was 71.2 dB on the stainless jar and 70.6 dB on the PVC jar, to me they essentially sounded the same loudness but the steel one did have a slightly different metallic sound (obviously lol). Overall I think this can be a very good option, as they require minimal time/materials to convert, should be able to mill most chemicals, and they're cheap enough to have one for each type. They also come in gallon size for not much more, seen a few for under $25.

Still, they may not be the best option for milling BP or similar live comps just to be on the safe side, but with lead media I can't imagine sparking being an issue. I guess time will tell if it lasts, the steel isn't super thick and there may be a chance of it cracking, but since it is vacuum insulated there are 2 walls so if it does crack it should still be contained and the jar can then be taken from service.

 

 

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[Powderman]

It might not seem obvious, but milling creates some heat and without a way to escape (vacuum insulation) it could build up significantly over time... Be sure to check it.

[wymanthescienceman]

Hmm, yes that is something to consider, very good idea. I'll have to do a test and run the mill for a several hours and see how much the temperature rises, if it ends up being too much I may have to break the vacuum and see if it helps. I can't imagine it would be too much of a deal with most chemicals with short couple hour run times but with things like MgAl that takes a day or 2 it may need a break every few hours or so.

[Arthur]

Ultimately it's up to you to find a safe place where your mill can run safely and cannot harm any body or any thing if it explodes. BUT no-one has enough space away from the house by a mile or so, with electricity.  People have used a hole in the ground, a couple of old tyres etc to mitigate the hazard of a mill jar exploding. There have been at least two incidents with mill sites among previous posters on this forum so while that's only two, it was two people maimed with surgery and hospital bills to cover.

 

If you really have to avoid the usual, proven functional mill styles -both mill and jar- please be very aware of the risk and hazard you take upon yourself, family and neighbours.

Edited by Arthur, 09 August 2023 - 03:35 PM.

[wymanthescienceman]

Arthur, do you have any references to these accidents that have happened? It would be interesting to know how they had their mill set up and what they were using as media and the jar type.

And as I said before these jars are better suited to non-live comps and single chemicals, the risk of explosion should be essentially none. Even if it was a flammable substance like charcoal or similar and it happened to cause a fuel-air type explosion a simple 3/4" plywood enclosure would keep it mostly contained or effectively dampened. It would be nowhere near the danger level of a jar full of black powder. My goal here was to find a viable alternative to home made mill jars that don't cost too much and are easily converted for use. I think it would be safer and more convenient to have several dedicated jars than using the same couple jars to mill everything. While the old Sponenburgh style jar is tried and true they can be expensive to make. Just checking current prices at my local big box type store it would cost nearly $30 just for the parts to build a 6" PVC jar if you already have the glue.

Sometimes new ideas come along and can be useful so I figured I would share what I learned, if you don't trust it or don't like the idea, that's fine, I'm here to learn with y'all and get input. Obviously precautions should be taken with anything new and testing should be done before trusting a new variable in your tool arsenal. Do whatever it takes to keep yourself and others safe in this hobby.