140 replies to this topic

[portfire]

well dont be shy show us your mill dean, (and everybody else to !)

LOL I'll sort some out next week when I've finally got use of the workshop again ...Start building my new one tomorrow, and once thats finished, it's pyro pyro pyro and oh yeah, more pyro

[kelly]

easy found ball mill motor
For those finding it difficult to obtain a VERY low RPM motor for a ball mill, try using a microwave dish rotating motor. It operates seperately from the magnatron and even though the microwave no longer operates this motor and gearbox are very seldom effected. It turns out about 3.2 rpm and can be upped to 20 rpm with the head worm gearing from an angle grinder, which disconnects as a seperate unit. By reversing the drive of the angle grinder it will operate at about 6 rpm, giving the 20 rpm final drive. Makes a neat, small package, without having to use a transformer, and no concern about AC voltage as the microwave operated on whatever current is used in the country of origin. By attaching a "Woc" plate to the final drive, adding sides to the "Woc" plate, and a lid that fits the ID of the sides, you have a ball mill,and a machine that will function as a star roller.

Good Luck and stay Green

[Bonny]

easy found ball mill motor
For those finding it difficult to obtain a VERY low RPM motor for a ball mill, try using a microwave dish rotating motor. It operates seperately from the magnatron and even though the microwave no longer operates this motor and gearbox are very seldom effected. It turns out about 3.2 rpm and can be upped to 20 rpm with the head worm gearing from an angle grinder, which disconnects as a seperate unit. By reversing the drive of the angle grinder it will operate at about 6 rpm, giving the 20 rpm final drive. Makes a neat, small package, without having to use a transformer, and no concern about AC voltage as the microwave operated on whatever current is used in the country of origin. By attaching a "Woc" plate to the final drive, adding sides to the "Woc" plate, and a lid that fits the ID of the sides, you have a ball mill,and a machine that will function as a star roller.

Good Luck and stay Green

Maybe a small star roller may work, but as a ball mill I think 20 RPM is too slow unless you are using a tiny jar or want to mill a batch of BP for 5 days at time...

[kelly]

Maybe a small star roller may work, but as a ball mill I think 20 RPM is too slow unless you are using a tiny jar or want to mill a batch of BP for 5 days at time...

Criticism of final drive RPM taken in good spirts, sounds like I'll have to increase RPM for use.
Thanks,Bonny!

[Bonny]

Criticism of final drive RPM taken in good spirts, sounds like I'll have to increase RPM for use.
Thanks,Bonny!

There is a formula somewhere for optimum milling speeds depending on jar diameter and media size. My 4" jars spin around 100rpm with brass media ranging in size from 3/8" to 3/4". It is not perfect but seems to work just fine for me. I usually mill BP for at least 6hrs, although I have never tested with less time...

[psiborg]

this may be the wrong thread, but I just wanted to propose using a golden syrup tin as a mill drum, the main advantage(apart from me having about 10 of them lying around) is that the lid would easily pop off from internal pressure, hopefully eliminating the risk of explosion due to accidental ignition. what do you guys think?

[dr thrust]

ermm best not! metal drums are a big no no, also that pop off lid may pop off spewing bp everywhere, i got my drums from here drums

[psiborg]

okay, I had a feeling you might say that. point taken, i'll find something else then.

[BrightStar]

Since you're also buying KNO3, why not order some of these as well:

http://www.inoxia.co...ategory/17.aspx

The 1.3l HDPE jars have lasted dozens of batches so far for me... They are a bit slippery on the outside but wrapping with a couple of bands of electrical tape helps the grip.

Edited by BrightStar, 05 July 2008 - 02:45 PM.

[Bonny]

Since you're also buying KNO3, why not order some of these as well:

http://www.inoxia.co...ategory/17.aspx

The 1.3l HDPE jars have lasted dozens of batches so far for me... They are a bit slippery on the outside but wrapping with a couple of bands of electrical tape helps the grip.

Adding elastic (rubber) bands on the outside works great too! And also costs nothing.

[Shake]

Hi everyone!
I'm new to the forum but have been tinkering with pyrotechnics off and on for some 20 years however just starting to get "serious" about it. I'm moving up from homemade bottle rockets to attempting my first shell, a 3" spherical...I'm so excited I feel like an expectant mother!
I just finished making my ball mill and tested the results last night...well impressed and I thought I made pretty good BP before; this new stuff burns incrediblely fast with no residue and a nice bit of gas created.
The ball mill was simply a set of aluminium rollers, an old fan motor, a plastic peanut butter jar and marbles for my media. The fan motor on low gives me about 70 rpm. I wrapped duct tape around the jar for some traction. Milled the charcol, then my KNO3, then combined and added S and milled for 2 hours...beautiful!
Looking forward to testing my lift powder in a few days, up until 1am last night making it.

[digger]

Hi everyone!
I'm new to the forum but have been tinkering with pyrotechnics off and on for some 20 years however just starting to get "serious" about it. I'm moving up from homemade bottle rockets to attempting my first shell, a 3" spherical...I'm so excited I feel like an expectant mother!
I just finished making my ball mill and tested the results last night...well impressed and I thought I made pretty good BP before; this new stuff burns incrediblely fast with no residue and a nice bit of gas created.
The ball mill was simply a set of aluminium rollers, an old fan motor, a plastic peanut butter jar and marbles for my media. The fan motor on low gives me about 70 rpm. I wrapped duct tape around the jar for some traction. Milled the charcol, then my KNO3, then combined and added S and milled for 2 hours...beautiful!
Looking forward to testing my lift powder in a few days, up until 1am last night making it.

Welcome

Very good, good luck with your first shell. However you may want to reconsider your milling media and change to lead or even ceramic at a push (cue debate on ceramic media). I assume that the motor you are using is of the brushless type?.

Digger

[Shake]

Welcome

Very good, good luck with your first shell. However you may want to reconsider your milling media and change to lead or even ceramic at a push (cue debate on ceramic media). I assume that the motor you are using is of the brushless type?.

Digger

I'm not really sure about the brushless aspect of the motor; is this from an ignition source concern?
Regarding the media, I know glass probably isn't the best however I did want ot give it a go and monitor the wear on the marbles. I figure if I have a good balance of BP plus the marbles the contact of glass angainst glass should be minimal.

[digger]

I'm not really sure about the brushless aspect of the motor; is this from an ignition source concern?
Regarding the media, I know glass probably isn't the best however I did want ot give it a go and monitor the wear on the marbles. I figure if I have a good balance of BP plus the marbles the contact of glass angainst glass should be minimal.

Yep the motor is to do with ignition source. If I were designing it for industry it would have to conform to ATEX and DSEAR in the UK (ATmospheres EXplosive regs and Dangerous Substances and Explosive Atmosphere Regulations) which covers more than just the electrical sparking aspect such as mechanical friction heating effects etc.

I am sure others will pipe in on the marbles aspect, I am not sure about sparking with glass. However do you really want little chips of glass getting into your bp? Just imagine a lift charge going wrong and shooting hundreds of little shards of glass in your general direction, mmm nasty.

P.S. lead media is easy to make and will produce a better product (although I use ceramic grinding media)

Edited by digger, 08 July 2008 - 12:31 PM.

[Shake]

Yep the motor is to do with ignition source. If I were designing it for industry it would have to conform to ATEX and DSEAR in the UK (ATmospheres EXplosive regs and Dangerous Substances and Explosive Atmosphere Regulations) which covers more than just the electrical sparking aspect such as mechanical friction heating effects etc.

I am sure others will pipe in on the marbles aspect, I am not sure about sparking with glass. However do you really want little chips of glass getting into your bp? Just imagine a lift charge going wrong and shooting hundreds of little shards of glass in your general direction, mmm nasty.

P.S. lead media is easy to make and will produce a better product (although I use ceramic grinding media)

I really didn't consider the use of an intrinsically safe motor and am quite sure a household fan motor is not. However, proper housekeeping methods should keep the hazard to a minimum by keep flammables away from the motor and keeping the BP tighly sealed in it's drum. Although I think I will investigate a replacement motor sooner than later.


I agree with your concern on glass media and am closely inspecting the glass balls after every batch milled for signs of deterioration. I will change at the first sign. I actually have stainless steel 1/2" balls on the way. Perhaps that will add to the media discusion as well; ceramic vs. lead vs. stainless vs. brass vs. glass