To ball mill or not to ball mill.....

[loaded4bear]

That is my question....

 

I have been gathering different star formulas to try this spring. I noticed that some include basic instruction, but most do not. I know that if the formula includes dextrin or similar (and it does not have Mg) then I can wet with water and alcohol and start rolling. But what about the need to ball mill? Are there any general guidlines to help determine if a comp, or parts of it, should be ball milled? Should I ball mill certain chems, certain types of comps or to a certain consistency or mesh for the star to perform the best???

 

I made a nice AP blue comp the other day and the AP I had was about the consistency of sugar. No problem going through a 40 mesh screen. I rolled up a batch of 4-5mm cores and after they dried, I noticed that the surface of the star was very rough and pockmarked. I was wondering if I should have ball milled the mix first without the copper. I lit one and it seemed to burn fine although it was a bit pale in color.

 

B10 Potassium perchlorate 38 Ammonium perchlorate 29 Copper carbonate 14 Red gum 14 Dextrin 5

 

What do you all think, I could use some guidance as to when to ball mill (or not).

[flying fish]

Copper carbonate is not a fuel, but red gum and dextrin are. Without the copper you still have a "live comp" (and in fact a more energetic one). Perchlorates should not be milled with fuels. They can be milled separately and screened in, though. This might help smooth out the burn.

[Mumbles]

That said, I still wouldn't mill ammonium perchlorate and any copper salts. There are extenuating circumstances with it.

 

About the only compositions I mill are occasionally charcoal streamers. A few, like some spider star mixes, require milling. Most however just benefit from it. The tails look more uniform and the stars burn better IMO when milled somewhat. I typically give it about 30min to an hour on average. This accomplishes the mixing, and makes sure everything is sufficiently fine.

 

I try to make sure all my chemicals are sufficiently fine. The majority come pre-powdered. Ammonium perchlorate happens to be one of the ones that comes granular regularly. This is due to the grain size requirements for high powered rocketry. You might want to read more into this subject as there is a lot written about it. The finer the material, the more reactive it will be. At a certain fineness, it is considered an explosive on it's own by the ATF. There is a lot involved with this particular material, and I honestly don't know enough to totally cover it.

 

Even with AP in there, I still like having an extra chlorine donor present. You may want to try grinding a small batch of AP, and remaking the star to see if there is any improvement in color, or if the paleness is a result of the formula itself.

[psyco_1322]

To make a very clear point, you should NEVER mill a live (burnable) composition, other than black powder based compositions. This does include charcoal stars as Mumbles mentioned, as they contain the same basic chemicals, but in a different ratio. If you are not aware, that includes Potassium Nitrate (KNO3), Sulfur (S), Charcoal ©, and the binder, most commonly Dextrin or SGRS.

 

Individual chemicals can be milled separately in a clean jar if it is necessary, but most of the time, a coffee grinder can save you the hassle. Milling any live comps, such as colored stars, will likely end with a mill explosion.

 

On another note, blues, along with other colors, don't really show their color very well on the ground. If you want a good representation of the colors, a shell works best, even if it's only a thrown together 1.5" shell.

[50AE]

It is also advisable not to mill live compositions as well, it makes you staying to the "greener" side. What I used to do when making BP, is milling the components separately to the finest possible level, and then mixing them together in the ball mill putting very little media. When the media content is almost negligible, it doesn't cascade from a long distance with hard hits, but moves softly with the mixture. This way your milling is extremely inefficient, but if works great for gentle mixing. I guess an even safer method is using a light media, like a few hard wood balls.

 

Remember that the dangers of milling living mixes also increase with the type of media, weight of media, the size of the ball mill drum and the milling action (planetary, circulary). For example the heavier and harder the media are, and the bigger ball drum, the greater mecanical shock energy on the mixture and the greatest danger. I'm pretty sure black powder could be made to explode by milling it in an industry ball mill with 200kg non sparking piece of media.

Edited February 25, 2013 by 50AE

[AirCowPeacock]

I recently switched to two part milling. I mill about 1/3 of the charcoal with the Potassium nitrate, and then the other 2/3 of the charcoal with the sulfur and binder. Then I screen them together. It works great, not quite as good as regular combined milling, but I feel much better about it.

[loaded4bear]

All great advise regarding live comps. I like the idea of using minimal media in the final stage of BP milling. I will adapt that for future batches. My original question was if there are any guidlines if certain chemicals commonly used in star formulas should routinely be baill milled to a flour like consistency.

 

I took Mumbles suggestion and made a small batch of the B10 comp. I ground up the AP to a fine consistency and used potassium perchlorate that I had already milled. This batch is drying now but looks very different from the first. My bet is that the color will look better with all of the components more intimately in contact with eachother (sounds like fun!). I would guess that the burn time will be longer as well.

 

What I used to do when making BP, is milling the components separately to the finest possible level, and then mixing them together in the ball mill putting very little media.

 

What do you do now?

[TritonPyro]

Mumbles, I have a good idea of c stars and have made TT. Could you describe a spider star? Always interested in effects for shells. Thanks.

[Mia]

Leaves behind a brief reddish fire dust.

 

Potassium nitrate 54

Charcoal (Airfloat) 32

Sulfur 7

SGRS or Dextrin 7

[Mumbles]

It's more of an effect than a formula. The formulas are all pretty similar to Chrysanthemum 6. They're all intended to be relatively quick burning charcoal streamers. The shells are broken hard, typically with a flash bag or heavily boosted burst. The idea is to throw the stars out hard and in straight lines. If you fire several of these in sequence, the overlapping charcoal tails tends to look like a spider web. This is the definition I've always heard. However even on their own, they're quite impressive and do look sort of like spider legs if you put that notion in people's minds before hand.

 

Degn Spider Web #1

Meal - 10

Potassium Nitrate - 7.5

Charcoal - 7.5

Sulfur - 1

Dextrin - 2

 

Degn Spider Web #2

Potassium Nitrate - 15

Charcoal - 9

Sulfur - 2

Dextrin - 2

 

Swisher Spider Web

Potassium Nitrate - 18

Charcoal - 9

Sulfur - 3

Dextrin - 2

Lampblack - .5

 

The first and third don't have to be ball milled. The second I've always ball milled, but in comparison to Mike Swishers formula, I don't know that it's entirely necessary. They're all in parts because they're all commercial formulas.

 

I am quite a fan of the timed spider effect.

 

 

[TritonPyro]

That last one was beautiful. The last effect was which formulation?. Thanks for the video, they were very nice. Would that have been a flash break or BP?

 

I really enjoy making charcoal effects. I still think they are a thing of beauty when properly made.

Edited March 29, 2013 by TritonPyro

[Mumbles]

I think both of those shells used Mike Swisher's Spiderweb star formula, which is the last one I posted. The ones in the second video were probably milled for a little bit, no more than 20-30 minutes just to grind all my nitrate down to a fine powder.

 

The inserts were all granular BP boosted with flash. I think it was actually a lack of BP, not flash, that made them sort of lacking honestly. The last break was a flash bag. It's not entirely accurate to say that it's either all flash or all BP. Flash broken shells still have a substantial amount of polverone in them. The shell has 40 1" comets lining the walls, all shimmed in. The flash bag containing between 12 and 15g of 70/30 flash with indian blackhead is tied onto the spolette or timefuse. The space in between the comets and flash bag is then totally filled in with polverone, and the top is leveled off and closed. The polverone, while often slow burning, does still contribute to the burst. You can definitely see the glowing cloud of polverone, and probably a few shattered stars, in the center of the final break.