Last questions (verifications) before milling first batch of BP

[braddsn]

Before I jump into my first batch of BP, I want to make sure my ducks are in a row. So please comment with any thoughts that you have on the following. I will also post pics as I go along. I have the Thumler's Tumbler model "B". I have 35lbs of .50 cal lead balls for media. I am making my own charcoal, using Eastern Red Cedar, I will grind it in a coffee grinder, then mill it along with my KNO3 and Sulphur. I will also throw 3% dextrin in the mix in every batch that I mill. I plan to use the standard 75/15/10 for all of my bp. Ball mill will be set up behind my pole barn, about 50 yards from my house, with sandbags around it. I plan to mill my bp mixture for 12 hours. Biggest questions that I have are, do any of you have personal experience with Eastern Red Cedar for charcoal? I have access to willow too, but I have read in many places that Cedar makes great bp. And, is 12 hours milling generally sufficient for good bp? Seems like 12 hours is the norm, but I have read on this forum where some guys are milling for 24 hrs, etc. Thanks guys! I am looking forward to getting started.

[Arthur]

Smaller mills usually take longer to mill powder for BP. I know someone who made powder in 3hours, I know others who allow 12 hours. Sometimes it's for convenience (leave the mill while you go to work) that people chose a time. Best plan is to do a batch, and take out a sample at (say) 3, 5, 7, 9 etc hours. then separately make a test batch of BP and determine the power of each batch. You should find that the results improve with milling but get to a level of no further improvement, which is where you stop.

 

You will find that there are subtle differences with different woods, maybe you have a small selection and use each for the best effect.

 

But a choice of wood and a choice of grain size usually means having rather a lot of powder in store.

Edited September 4, 2014 by Arthur

[rogeryermaw]

Thumlers is a great machine. I recently got one as well. I hear 35lbs everywhere but I'm not sure that machine can turn that much unmodified. I'm using about 20lbs and mill around 300 grams of composition at a time on a modded drive roller. The mod is simple. Slide a piece of 5/8 heater hose over the traction parts on the drive roller and 3/4 over that. Then I run the mill for 2 hours, check for clumping and 2 more hours. The powder that comes out of that is some of the best I've made.

[Bobosan]

12 hours seems way too long for that mill. I find that 4 hours is best for my milling using 35lbs media, Thumblers drum and comp charge of 1.5lbs. Never had any clumping issue with this timing.

 

3% dextrin in the mill is more than adequate for a 1.5lb comp charge. I usually run between 1% and 2% and get plenty hard grains after granulation.

 

It's a pain to do, however, Arthur's suggestion of taking samples at regular intervals of mill run can help to determine ideal run time for your mill setup.

[dagabu]

The model B with a proper load takes about 2 hours to fully mill a load of BP. You will likely not see a difference with powder that is milled longer.

[Arthur]

You can either guess or take samples over time to determine the optimum mill time. A sample every hour will let you determine the optimum run time but if evidence is that good powder needs n hours then try that and see whether it's good enough. I'm not aware that over milling can reduce the power, but under milling will not let BP ingredients reach their maximum potential.

[pyrokid]

Depending on the nature of your charcoal, the coffee milling may not be necessary. I view the blade milling of charcoal as a hazard. All my homemade charcoal is so soft that it doesn't require individual grinding. I do make sure the chunks going into the ball mill are small enough for the media to do work on them though. Old meat grinders are great for this.

[Bobosan]

You can either guess or take samples over time to determine the optimum mill time. A sample every hour will let you determine the optimum run time but if evidence is that good powder needs n hours then try that and see whether it's good enough. I'm not aware that over milling can reduce the power, but under milling will not let BP ingredients reach their maximum potential.

 

In addition to maximum potential vs. mill time, you might start having clumping issues on mill runs longer than necessary.

 

As Dagabu mentioned, 2 hours minimum mill time for a 15lb Thumbler barrel provided you have pre-milled chems and optimized you milling machine. YMMV

[Mumbles]

I'd second the meat grinder over the coffee grinder. A batch of BP for you will be between 700 and 1000g. That's 105-150g of charcoal. If only for efficiency, that's going to be quite a lot of batches of charcoal going through the coffee grinder. After my accident I refuse to use anything without a separated motor and grinding chamber. With a larger mill jar like this, you can probably just use the charcoal as is, or perhaps just crush it to pass a 3 to 4 mesh screen

 

Even starting from coarse materials, you're probably looking at 4-6hr milling time at the most.

[BurritoBandito]

I would personally recommend crushing the charcoal and screening it prior to milling, for the off chance that there may potentially be a foreign object in the charcoal. Bobosan suggested to me the idea of passing a magnet through the crushed charcoal to remove ferrous materials which may be hidden in the batch. Very reasonable advice.

[rogeryermaw]

excellent advice as i have often used scrap 2x4's as a source of pine charcoal. you can't even trust the trees on your own property. i have wrecked chainsaw blades on bullets and other metal buried deep in tree trunks.

[braddsn]

Thanks a lot guys for the great advice. As far as metal in my wood scraps, I run a metal detector over all of my logs before I mill them so that won't be an issue. That's good that I will only have to ball mill a max of 4-6 hours. I was thinking I would have to go 12 hours or more. I will try 4 hours and see how it goes. It was a hell of a mess crushing the charcoal and grinding in coffee grinder. Wow.... messiest stuff I have ever dealt with! The whole time I was using the coffee grinder, I couldn't help thinking about Mumble's ordeal... I kept the fire extinguisher close. I will post after I have my first batch of bp all done.

[Arthur]

Remember that you don't get time to use an extinguisher, the flame is over in tenths of a second. The heat and smoke clear later. That's why you need to work as safely as possible and have suitable ppe and minimise the amount of hazardous material open at one time. A tenth of a gram of BP does little damage but 10g, 100g and 1Kg are bigger problems and could cause minor demolition.

 

If you own 10 kilos of something then maybe you should split it into smaller bottles. In the UK, BP in storage must be kept in 500g plastic bottles, never bigger. And the bottles kept in separate slots in a wooden box.

[BurritoBandito]

Not to downplay the very real dangers of using a coffee grinder, but Mumbles wouldn't have had such a bad accident had there not been live BP present. If you choose to use a coffer grinder for pre processing your charcoal, make sure there are no flammables anywhere around. Personally, I think crushing it with a piece of 2x4 or 4x4 in a bucket is quicker, cleaner, and safer. The metal detector is a good idea, but I'd still screen it. There could be non-ferrous contaminates as well. Whatever can be done to minimize the risks should be done.

[braddsn]

Yeah, my process for the charcoal is as safe as it can be.. or at least I think so. I have a huge sliding door on my barn, and I am doing it just outside. I am first crushing the charcoal into small pieces in a bucket with a heavy metal rammer. Then I am dumping the pieces into the coffee mill and grinding it pretty fine. There is nothing flammable anywhere near me... so if the little coffee mill were to catch fire, I would just get back and watch it burn.. or just put it out with the fire extinguisher. As far as milling my BP, I built a small platform on the back side of my barn (outside) and surrounded it with sandbags. So, if it were to explode, nobody will be anywhere near it.. and hopefully with the sandbags, it wouldnt damage my barn. And Arthur, PPE is priority one..personally, whether I am just grinding up some charcoal in the coffee mill or rolling stars, I will be wearing goggles and a dust mask. And I have made a list of things (like green stars for example) where when I am working with them, I will wear a full respirator. Burrito, I will definitely screen all of it before it goes in the mill. That makes good sense.

[Arthur]

PPE means aiming for 100% body cover in a fire retardant fabric, or minimally, spark resistant welding overalls.

Nomex jeans may cost a lot but so do medical bills. I really don't care how "odd" it looks in a warm climate to wear full overalls, wearing bandages looks odder and hurts much more.

 

One of the guides to good pyro charcoal was simply put as "pick the lightest, fluffiest, softest lumps and discard anything that needs tools to crush it". Fast powder comes from the biggest (volume) kilo of charcoal.

[FlaMtnBkr]

I would wear a respirator anytime you are working with chemicals, including charcoal. The first time you don't you will know what black boogers are. The pieces that air float are the smallest and any small micron particle is not good in your lungs.

 

For particles you don't need the expensive respirator cartridges that filter out organic vapors. But those little dust masks are a joke. They get full of water vapor from your breath after a minute and most of the air coming in is from around the edges. In medicine they aren't to stop you from breathing in crud, they are to catch junk that might come out of your mouth that could contaminate a surgical field or other patients that could get sick.

 

Inert sand will give you emphysema if you breath it long enough.

[braddsn]

I will take that advice. Dad just gave me a really nice (fairly expensive) respirator, so I will just use it whenever I am working with anything, even charcoal. Easy enough. It is comfortable and doesn't restrict breathing at all. I weld, so I have a full set of welding (flame retardant) clothing. I will just wear it. The long sleeves will get hot in the summer, but better than burns!

[BurritoBandito]

Dag's a pretty cool guy.

I will take that advice. Dad just gave me a really nice (fairly expensive) respirator, so I will just use it whenever I am working with anything, even charcoal. Easy enough. It is comfortable and doesn't restrict breathing at all. I weld, so I have a full set of welding (flame retardant) clothing. I will just wear it. The long sleeves will get hot in the summer, but better than burns!

 

[Shadowcat1969]

Keep in mind that as far as PPE goes, a respirator is a good thing. However, if you are in a flash fire, it will possibly melt to your skin.

 

There is a balancing point that we all have to reach for each of us, as far as what to wear when. For example, I use a respirator, but I wear it over a balaclava when I'm working with BP (for example). It's not as effective respirator wise, but it gives the protection in the areas that I want it too.

 

And safety glasses that wrap as close as possible to my face to keep flame from "wrapping" around the edges, because it will.

[dagabu]

Keep in mind that as far as PPE goes, a respirator is a good thing. However, if you are in a flash fire, it will possibly melt to your skin.

 

There is a balancing point that we all have to reach for each of us, as far as what to wear when. For example, I use a respirator, but I wear it over a balaclava when I'm working with BP (for example). It's not as effective respirator wise, but it gives the protection in the areas that I want it too.

 

And safety glasses that wrap as close as possible to my face to keep flame from "wrapping" around the edges, because it will.

 

+1

[braddsn]

Makes good sense. I helped some of my firefighter buddies put out a house fire a few years ago. I was on a tractor moving debris. During the action, I ended up getting a little too close to the fire a few times, and ended up having some lycra melt onto my skin. I will never forget that pain!! It blistered up pretty bad. I am super careful with everything I do.. I have a sawmill, and I do a fair bit of logging as well. Logging can be super dangerous if you get careless, and don't use proper PPE. I have always been the guy to take the extra 5 minutes to gear up properly, and pyro will be no different. I feel rather comfortable doing everything in this hobby so far, except the good ole vitamin F. I am not planning to attempt that until I gain some experience with all the other chems. I have watched countless videos about it, and could probably make it in my sleep.. but I think a guy needs to gain some experience before even trying that. Salutes will be a must in the future, they are my favorite.. but that is going to have to wait a while. I want to keep my fingers.. need them to type on this forum.

[rogeryermaw]

sounds like you are taking a healthy approach to this hobby. all i have for safety equipment i stole from my lab: a full face shield and some elbow length gauntlets. i don't sweat the dust too much as i do most of my work outside. black boogers are few and far between but i know i could do better. i try to minimize risks as much as possible with static and keeping open compositions to a bare minimum but there are areas we could all improve on i'm sure. you're off to a good start, brad, just keep that mentality and don't ever take that attitude that "just this one time" or "i'm only working on something small/not energetic".

 

i hope you're enjoying that new mill, by the way!

[FlaMtnBkr]

You could make a custom respirator face mask out of asbestos!