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Causes of ball mill accidents?

Ball mill black powder safety

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#81 Guest

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Posted 25 August 2021 - 07:47 PM

I was taking apart some fiberglass tent poles to make paper tube rolling mandrels, and rammers for small rockets and saw that the "shock cord" that holds the sections together looked a lot like that ESD elastic cord.  I thought 'Shock Cord?!' and wondered if that stuff was conductive.  I don't think so.  But while searching for information about it, I came across this stuff.  Think it will work for our application?        https://www.wellscro...ric-bungee-rope


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#82 Bourbon

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Posted 25 August 2021 - 10:31 PM

I didn't even know it existed till you just showed me.. :D I have no idea. Might be worth looking into.



#83 Guest

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Posted 25 August 2021 - 11:01 PM

I tested the tent pole bungee with an ohmmeter, and it is no more conductive than air.



#84 Guest

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Posted 21 September 2021 - 08:51 PM

EDIT:  I was re-reading my post above and realized I wasn't making BP, I was milling charcoal!  I always do that outside because of the dust, and just mis-remembered.  I'm almost as burnt out as my retort cans  lol, sorry.

 

Anyway, I just tried the ESD brush thing with the TENS pad electrode. 

Results:  Successful!

 

MadMat, you're a frigging genius!  The brushes don't have to touch the jars at all to dissipate the static!  I scraped the paint off the frame/chassis to get a good ground, stuck the electrode on, (with the insulation removed from the conductors, so they were like really long, thin paintbrush bristles) and instantly the arcing was gone.  I could peel the pad back off the bare spot, and the arcing would immediately start again.  Pad on metal...arcing gone.  Did it about 2 dozen times just to be sure I wasn't imagining it.  I will make a video sometime to show how it works, but it does work.  I feel a lot safer now, and suggest that this be some sort of standard thing for everyone.

 

Word of caution-  It's anecdotal evidence for sure. I don't know how effective it will remain in different environments, or in different weather conditions.  More research is needed.  (as always...)



#85 Guest

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Posted 25 October 2021 - 08:09 PM

Quick update:

After a season change and over 120 hours of milling, I still haven't seen the static spark again. The brush is still on, doing it's job.
I don't know what happened to the video, I will make another and repost when things slow down.
Thanks for all the great information, and stay safe everyone!

#86 Guest

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Posted 09 November 2021 - 10:17 PM

As promised, here's the video again.  Youtube takes a lot of the quality out, sorry about that and the shaky video.  I'm not the best videographer...

 

https://youtu.be/rfGMRw7IJEo

 

Please let me know if there are any problems viewing the video.  This is the first video I've ever uploaded to Youtube, so it's all a learning experience for me



#87 Arthur

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Posted 10 November 2021 - 06:28 AM

If you want conductive rubber then you have to add "acetylene black" during the compounding, it can't be added later.

If you want conductive fronds then look for simple carbon fibre tow probably available from places that do carbon fibre panels for cars (etc) or their wholesalers, take an inch of carbon fibre tow (lots of strands!) thread it into a cable ferrule with a suitable piece of wire and crimp it



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Posted 30 November 2021 - 11:35 PM

https://www.osha.gov...ions/1987-07-18



#89 GoldenStars

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Posted 03 September 2022 - 10:45 PM

Hi all,

I'm digging up this old topic. I will give a quick sketch of my safety concern and what I want to do.

 

I have have recently bought 25kg potassium nitrate "for gardening purposes ofcourse", i'm not new into the scene and did pyro when I was young kid for approximate 4 years in total duration. Because I don't like to create large batches of compositions I decided not to build my own ballmill but just buy a mini rock tumbler. I think I had milled a few batches with the mill and then because circumstances I had to move from a "house" with woods in the backyard to an appartment. I did mill outside of course, and in a spot where explosion "would not be a problem". I had a long extension cord to pull before approaching the mill. I used ceramic ball media and had not problem at all. But time has passed and didn't do pyro for 10 years or so "I came across some potassium nitrate". 

 

I didn't kept the ballmill and equipment and sold it (and all other stuff). So i'm thinking to buy again just the simple rock tumbler, and put it on my different appartments balcony. The balcony has sadly a lot of glass so when things go awry I will have cheese holes in my windows. I was indeed thinking as people suggested in this topic to create a explosion barrier just in case.

About the static discharging issue, my home has only electrical earth at a few places. So conducting an eventual charge to earth can be a problem. And also i'm not sure anymore if the rock tumbler is double insulated, but I think there must be an earth connection because of the metal parts it can have. I'm pretty sure the vessel is of rubber which has non-conducting electrical properties, which can be the problem part. 

So what do you think, should I "risk" the pyrotechnic benefit, or "blow up my house" :-)?

The good news is that I'm only planning blackpower and blackpowder-like compositions, which are low risk.

Have a good day all. 


Edited by GoldenStars, 03 September 2022 - 10:47 PM.


#90 mabuse00

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Posted 04 September 2022 - 08:16 AM

 

or "blow up my house" :-)

Is even your house...?

 

Considering the circumstances you describe, I would assume there are other tenants in this house beside you?

Then it's a little against common sense to pursue pyro at all...

 

In terms of ball milling safety, my solution is double & double component milling:

https://pyrodata.com...Manufacture.htm

 

You still have to sieve the parts together but if you do that outside in humid climate I'd say the risk is acceptable - very low.

Some years ago I compared the burn rates of the standard and the double & double processes - I found no difference (any different opinions/experiences here?)

 

 

PS:

 

imho the smaller tumblers all suck... If the setup runs well you get some 120-140g/3h. Refilling the jar every few hours makes a huge mess, every time...

Personally I like nozzleless rockets, and with these you use up a days production in no time...

I bigger mill would be much more efficient and reduces the workload significantly.







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