Ball Milling FAQ

[OldMarine]

Okay, I've got the mill, media, chemicals and a safe milling spot. Now once I get a run of powder made what should I do with it? How much saved as is and how much to granulate? I've found nothing addressing this but feel free to correct me! Edited October 21, 2015 by OldMarine

[Ubehage]

Okay, I've got the mill, media, chemicals and a safe milling spot. Now once I get a run of powder made what should I do with it? How much saved as is and how much to granulate? I've found nothing addressing this but feel free to correct me!

Usually, you want to granulate all of it.

Meal-powder, as it is from the drum, is a dusty as messy thing to work with. And it will burn a bit faster after granulating.

 

If you plan to roll stars, or otherwise use it to cover smaller stars, then you don't want to granulate it.

Edited October 21, 2015 by Ubehage

[OldMarine]

I'm starting with Gerbs and the like so I don't need lift as yet. That said, I only have a HF setup and would like to make a good amount while I'm up on the hill. Can I granulate it all then re-pulverize it later if need be?

[rogeryermaw]

Yes if you granulate without a binder. There is much debate on the topic of binder vs no binder when granulating your b.p. if you consolidate well I find my grains plenty hard without binder and that makes it much easier to re-powder them later. Also, when ramming rockets and gerbs, you'll find lower instance of cato if your fuel grain is better consolidated, which is more easily accomplished with no binder. The advantage of ramming b.p. into gerbs etc.that has been granulated, is less mess of dust flying during the ramming process. Edited October 22, 2015 by rogeryermaw

[OldMarine]

Yes if you granulate without a binder. There is much debate on the topic of binder vs no binder when graduating your b.p. if you consolidate well I find my grains plenty hard without binder and that makes it much easier to re-powder them later. Also, when ramming rockets and gerbs, you'll find lower instance of cato if your fuel grain is better consolidated, which is more easily accomplished with no binder. The advantage of ramming b.p. into gerbs etc.that has been granulated, is less mess of dust flying during the ramming process.

Hmm...should I forego the dextrin?

[rogeryermaw]

There are two camps here. I am firmly in the no binder side. I find dextrin unnecessary in b.p. It's great for binding stars but my b.p. is 100% b.p. unless rolling it onto rice hulls.

[schroedinger]

Roger are you speaking about water or alcohol binding?

 

If you use alcohol then I'am 100 % on your side, as long as the charcoal has enough resins in it, no additional binder works like a charm.

If you water bind, use 2 % dex and the granules becomme perfect. Just mill it with the bp.

 

Since you are making gerbs, you wan't only a fine granulation of the whole comp. I would recommend that you use window screen for ricing, or corn it. Keep everything from 20 - 40 mesh as lift or brake for later projects, and everything -40 goes into your gerb mix.

 

When making gerbs, make upthe mix, and granulate through window screen. This will help a lot with the dust, speciallyy when using the rod and funnel method.

[OldMarine]

@rogeryermaw

@schroedinger

 

Thanks for the info. Will alcohol work if I'm using commercial airfloat charcoal or will I need to use a binder?

I suppose I could go ahead and make a batch of cedar charcoal if that would serve better.

[schroedinger]

Yes you can be sure that the cedar works better. Commercial airfloat didn't gave good results. Also you can't expect a good lift from commercial airfloat and a HF mill. But you will need the power ti make a gerb with high flame colum.

[bigbuck]

is spf wood ok for making charcoal airfloat? and is homemade charcoal better than commercial stuff

[Ubehage]

Hmm...should I forego the dextrin?

I prefer to mill my BP without dextrin, and add what is needed when I granulate it. (Dextrin dissolved in water)

[Mumbles]

is spf wood ok for making charcoal airfloat? and is homemade charcoal better than commercial stuff

 

 

In every instance I've come across, home made charcoal is better than commercial charcoal. By commercial charcoal I'm specifically referring to commercial airfloat or coarser charcoals. You can certainly purchase top quality charcoal if you want to pay for it.

 

As far as the SPF charcoal, a lot of people use it. The quality will depend on what the actual wood is. SPF stands for spruce, pine, fir, and is more a product of local availability. White pine is common around here, and makes good charcoal. Basically if it is lightweight, fast growing, relatively free of knots and things, and not sappy it should make good charcoal and good BP. Larger lumber more designed for load bearing applications tend to be a harder, denser wood (southern yellow pine is common) and is less desirable for fast burning pyrotechnic applications. It tends to make nice sparks however.

[bigbuck]

thanks mumbles, I was just curious, I actually made some in a retort and ball milled it to a fine dust, very very messy that's why I was asking, I also read on here somewhere about using hardwoods such as oak, I have it readily available and already cut into small enough pieces

[Mumbles]

Oak tends to not be very desirable unfortunately. It's too hard, dense, and slow growing generally. Many varieties of wood sources have been investigated. I included some sources below.

 

http://wichitabuggywhip.com/fireworks/charcoal_tests.html

http://www.fireworksnews.com/Item/BlackPowderManufacture

"Effect of Different Charcoal Types Upon Handmade Lift Powder", Charles Wilson, Journal of Pyrotechnics, Issue 10, Winter 1999.

"A Systematic Study of the Performance of Charcoals in Pyrotechnic Compositions", Roger O'Neill, Pyrotechnica XVII, November 1997

[OldMarine]

I've been cooking my own Eastern Red Cedar but have recently purchased some Red Stem Willow from a fellow pyro and have been very impressed with it. I'll admit that it seems faster than my own charcoal.

[otto]

Here's my 2 cents as a novice. My belief is that most of the performance of BP is in the milling and the processing. I have successfully flown 1/2" endburners with commercial airfloat. A decent mill, properly charged, run for a reasonable time, granulated with hot water and dried fairly quickly should produce serviceable BP. NOW..... Additional performance can be attained by the substitution of "boutique" charcoal. Binders of any kind, as I understand, always inhibit burning performance. Proceed at your discretion or need......

 

The first run of BP I made with coal other than comm airfloat used some TLUD cigar box stuff. The dust right out of the mill went "POOF!" as opposed to "PFFFFF". Remember, I flew a number of endburners with the "PFFFFF".

 

I've always added 1% dextrin figuring it wouldn't be enough to limit performance (much) and if I needed more I could add at any time. Just my experiences, YMMV....

 

 

[DavidF]

Mumbles, I have to disagree with you about oak. The Pyrotechnica article you cite puts it above pine, Goex, and willow in performance.

 

I have retorted my own red oak splits in batches of 20 pounds or so. After running it through a Waste King garbage disposer, I milled the -40 mesh stuff with stainless steel media the size of peas. It made excellent powder. In nozzleless rockets, screen-mixed propellant made with milled red oak charcoal outperformed some other propellants (made with 'hot' charcoals) that were milled as complete mixtures of 75-15-10.

 

I have separated the charcoal into various size ranges and used it at 60-80 mesh for tails in rockets as well. When it is milled, it works very well in spider stars as well. I have found the red oak charcoal to be good for all pyro applications, depending on particle size.

 

I agree that for most pyros, larger particles of softer charcoals are a much more convenient choice when it is desired to simply throw unsorted ground charcoal, sulfur, and crystalline potassium nitrate into a mill and run it. That's not what O' Neill did in his Pyrotechnica study, and it's not what Danny Creagan did in his charcoal tests either. IMHO, the devil really is in the details when evaluating charcoals for black powder. I think the many differing opinions on the value of charcoals arise from the fact that there is no standard way of making black powder in the amateur pyrotechnic community.

[Mumbles]

I clearly should have checked the references I provided. The species he tested, Quercus chrysolepis, was in fact one of the fastest. I fully agree with you that the devil is in the details. I would expect that like most families of trees, that there is variability among the members. The few times I've tried oak charcoal, I was underwhelmed. It's entirely possible those were some of the harder, slower growing varieties. Thinking back, that is potentially an issue of milling time and hardness of the charcoal. 4hr for soft charcoals like willow is plenty, but harder varieties logically may take more time to achieve the same level of incorporation and particle sizes.

[OldMarine]

I've got a bag of ¼" stainless bearings that I plan to try Dave's charcoal milling method on with some oaks and maple woods. I figure I can run it for a couple of days at a time and see what it does.

[otto]

IMHO, the devil really is in the details when evaluating charcoals for black powder. I think the many differing opinions on the value of charcoals arise from the fact that there is no standard way of making black powder in the amateur pyrotechnic community.

 

As a process improvement guy I'll give this a "two thumbs up"! How many variables other than the "kind" of charcoal?

 

How was it cooked and was it more or less than optimum? Diameter of the jar. LIft bars, hex or just plain round? Is the jar unlined and hard or lined with something soft like rubber? RPMs, type and size of media, and % of charge for both media and comp likely play a role. Let's not even mention sourcing ingredients.Time, temperature, humidity.... How many are there really?

 

This sounds like a great candidate for a DOE.

,

I don't dispute that "better" charcoal won't make a difference by itself (everything else being equal), but to generalize the quality of a finished product that has many variables based on only that one might be only a partial conclusion. Even if we assume that good charcoal is a significant contributor perhaps as DavidF suggested, a "substandard" charcoal can be accounted for and "equalized" by adjusting another variable (mill time for example).

 

My plan would be to standardize as many of those variables as possible. Then when I know one changes only then is it likely that the significant effect is a result of that singular change. Details........yeah.

 

Or we can just call it "good enough". No disrespect directed at anyone. I'm far from ignoring or insulting the experience here. Just supposin'.....

[Raceman17]

Has anyone tried to get replacement ball mill canisters from harbor freight?

[dagabu]

I have a some tools from HF and lets just say that it is probably cheaper and faster to buy a new rock tumbler than to get parts from them.

[otto]

Not HF but these look to be Thumblers replacements:

 

For Amazin mill jars click here.

 

[patsroom]

Would making one from PVC be a option? It would be much cheaper than buying one from HF. Just an ideal...........Pat

[otto]

Like this: http://www.amateurpyro.com/forums/topic/7179-bm-jar/?p=94375? Lots of good stuff from this guy......