Trying for consistent lift powder.

[Mumbles]

A couple of tips that may help in the future.

 

You can re-screen the granules after drying for a little while. This helps to make sure everything is more uniform, and largely eliminates significantly oversized granules. If you've ever seen Mike Swisher's Polverone directions, he describes it. You scoop it back onto the screen and sort of roll the composition back through the screen. You want to round off some of the rods and worms, without smashing everything back together. It's a little difficult to describe, but after an hour or two of drying, it's actually fairly easy. Doing this, I usually get less than 5% +4 mesh material. You can usually crush it a little to get it to pass too if you want, or just add it to coarse polverone.

 

Definitely dry in thin layers, and stir every so often. Use a few sheets of paper if you need to. This also helps to prevent granules from sticking back together. I usually just use my hands on news paper sized sheets. Combs with coarse spacing or some of the teeth removed are also popular. If you're going larger scale, a rake can make things easier to handle.

 

As long as you dry it within a day or two, it's fine. With stirring and some airflow, I've never worried about crystallization. There are a lot of strong opinions on this matter, and this is my own. Often the same people who admonish getting BP too wet or drying too slow because they think results in larger crystals, are the same ones who tout getting charcoal stars nice and wet because they think the dissolved nitrate crystallizes inside of charcoal particles and makes smaller crystals and burns faster. The ratios are different of course, but I find the two ideas to be hard to reconcile. I'll leave you to form your own opinions.

 

I would also recommend grading through both a 4 and 12 mesh screen once totally dry for 2FA. As you probably have seen, you can't assume everything is smaller than the screen you granulated through.

 

I've personally had mixed results when trying to lift shells under 1lb with 2FA. The performance is more variable and sensitive to certain factors than I'd prefer. I tend to use 4FA sized powder for 3" and smaller shells and 4" ball shells. You'll have to find out what works for you.

[Arthur]

Small shells need smaller grades of lift, because the mortar is shorter. A grain of cannon powder takes longer to burn than a small shell takes to leave the mortar. IMO it's 2FA for "hand" size shells 1FA for "both hands" shells and 4FA for shells you hold in your fingers.

[schroedinger]

Or to put it into other words:

Up to 3" 5 or 4 FA

4" 4 of 5 FA

5-8" 2F

 

Also for everything up to 4" MCRH work great, after that you have to test how powerfull your hulls are and adjust for this and/or higher hull/bp ratio like 9:1

One ounce per pound shell weight until 10 lb after that 1/2 ounce

Edited December 14, 2015 by schroedinger

[Merlin]

Thanks for all the comments. I knew I had the milling down correctly but this explains why I usually get anywhere from poor to hot BP with most poor to just OK. I will apply all the suggestions on the next attempt. I wonder how many folks corn as opposed to wet granulating.

[Merlin]

Or to put it into other words:

Up to 3" 5 or 4 FA

4" 4 of 5 FA

5-8" 2F

Also for everything up to 4" MCRH work great, after that you have to test how powerfull your hulls are and adjust for this and/or higher hull/bp ratio like 9:1

One ounce per pound shell weight until 10 lb after that 1/2 ounce

That makes sense. 5 inch will be my maximum size due to space limitations.

Even so it seems huge compared to a 4. Now I got to copy and print all these good suggestions!

[Mumbles]

I can't imagine using 5FA for anything but priming if your BP is even halfway decent. Using 2Fg (-16+30) is very violent as it is. Something significantly finer is asking for trouble.

[Merlin]

I plan to use 4FA up to 3 inch and 2 FA for 4 and 5 inch. The terms were a little confusing for me because I am accustomed to gun powder like ffg and fffg the latter being pistol powder. ffffg is priming for flint locks not used at all with percussion. I don't know the particle size of 5FA but I think for lift 4FA is pretty fine. I have not used it for lift. I have never been consistent with my BP so I made a few 2lb bags last year and determined lift height with baseball's for each and used the appropriate lift weight for for each. That is why I am pursuing consistency in my BP. I am reasonably sure my problem lies with granulating and drying. I have received some good advice to correct my procedure here. I bought a good mill (40 lb) turning 60 rpm. A cement mixer for rolling stars and a 40 ton press for Crossettes. I am tempted to try one run of BP pressed and corned. But if it were acceptable to use MCRH for lift I would as I can make large amounts quickly with the cement mixer. Forgive my ramblings.

[FloridaCracker]

If you try corning your BP, I would suggest adding a bit of water and then breaking up the pucks right after they are pressed. They will break apart much easier when still damp. If allowed to dry, especially if dextrin was used, they are very hard like porcelain and quite a bit more effort to break apart.

[braddsn]

Merlin, I am not sure how much this will help you, but here is what I have experienced. I estimate that from the time I started doing pyro until now, I have put maybe 700 or so shells in the air. I have personally found that the power of my lift powder varies, and sometimes quite a bit. To try and achieve consistent power, I have refined my methods to the best of my ability, and I am meticulous about properly drying and sizing everything. I use 4FA for 3, 4, 5, and 6" shells, and I use 2FA for 8's. My theory goes something like this: There are a lot of factors that go into the power of lift powder like: How you cook your charcoal, species of charcoal, how much dextrin used, how much water used, how much alcohol, your drying method, etc etc, you get the point. All of these things are tiny factors, but in all can add up to quite the variance. Then to add to that, shell altitude can be affected by the clearance between the shell and the mortar wall, and also by the mortar length. A lot of folks will claim to have 'perfect' bp, or perfectly consistent bp.. I am not one of those folks. Furthermore, I am a busy guy and don't have the time to spend hours figuring out why all of my bp is not exactly the same...so I simply granulate 20-25kg of 4FA, get it good and dry, and store it in airtight containers. Then, when I start testing shells, I simply adjust the amount of lift until my shells are reaching the altitude that I want them to. I record that % value, then every shell from that point on I just use that amount. It may be 12% of shell weight, or it may be 16% of shell weight. I don't get all caught up on how much it takes... rather, I just use however much it takes and forget about it. bp is fairly cheap. YMMV. Good luck!

[dynomike1]

Well put Brad. But if you think about it you have +or- a second at apex, so that gives you a little lead way. It seems to me the charcoal is the biggest factor in this. I don't disagree with the other factors, i just think charcoal is. I feel like i have as fast of BP as anyone else but it will still vary a little from batch to batch. If i have say like 2sec. variance(example) in 2 batches i keep them separate and adjust my fuse. I don't see how from shell to shell you could not have a difference in milliseconds, in seconds i start investigating. Just my dumb way of thinking.

[Merlin]

Thanks. You guys are using an enormous amount of BP! But in my place I mill 1 kg per run. When finished say 4 bags around 10+ lbs of varying strength BP. Why not combine and mix it all in a large container. What ever it averaged it would all be consistently the same?

[schroedinger]

If you mix 'em well you should have consistent results inside this batch. But you really should try to work out any big variances.

[braddsn]

Merlin, that's exactly what I do. In other words, before I even start building shells for the year, I go ahead and granulate 20-25kg of lift (like I stated above). It all gets mixed together, then when I start testing shells, I quickly get dialed in to a certain percentage and I am all set.. same with burst. I make all of my lift and burst before building any shells. And what Mike said is also important... you can also adjust your timefuse if needed. Mike I agree, the charcoal is likely the biggest factor. Also, there are a lot of different places to get KNO3.... quality and purity can vary there too.

[dynomike1]

20-25Kg? I have never weighed mine, but i start out with a 5gal. bucket each of lift and Mcrh. That's good for around 70 shells. The thing about it everything you do is going to vary one way or another, quality of chemicals, dia. of shell, weights of comp., humidity, heat, etc.. Depends on how close you break your timing down, there is a point that there is no consistent lift. After i have watched some of these rockets, makes me wonder how i could get a bad break. A Lot of problems that i see newbies having is due to not holding the shell together long enough to get a good break. Thanks to Carbon 796 we figured that one out on me.

[Merlin]

Thanks to everyone. I remilled my BP and granulated to pass 12 mesh retained on 20 mesh. 25 grams is what I use to test baseballs.

Ball reached 800 feet. Good enough. Don't know how I got by last year - just granulated 4 mesh and used it. Now I have true 2fa, 4fa, and 5fa- priming instead of a mix of Cannon powder. I'm two years in and still learning.

[braddsn]

Merlin, me too. I am still in 'learning mode' and I am 2 years in. There is a lot to this hobby.

[MrB]

Im close to 20 years in... Still learning. If anything, the rate of learning only goes up.

B!

[lloyd]

Hey Merlin!

I'm FIFTY years into making fireworks, and still learning! <G>

 

Lloyd

[Merlin]

Lloyd fifty is pretty young.

I am 61. Retired, took up pyro for a hobby. I agree with MrB this hobby provides endless opportunity for learning something new. Having a analytical Chem background helps a little but Pryo is quite different. I have made match grade ammunition for a wide variety of rifles, built and flown model airplanes but pyrotechnics is very complex and never ending and I seem to be addicted to it. Perfect for an old dog that still wants to learn new things.

[lloyd]

Merlin,

I'm 50 years making fireworks! I'm almost 66. <G>

Lloyd

[Merlin]

That explains why you are a leading expert. I saw your pictures in a article so you look like you could be 50. Of course I don't look 61 either

[MrB]

Don't flatter your self Merlin. The beard on your profile picture makes you look like you are one hundred years old, or more.

But at least you have the sense to use a fire retardant cape when your out lighting things...

 

More on topic. Pyro is like life, only more so. You keep learning till you die. Hopefully, when you die, someone else learns from it...

B!

[Merlin]

I am going to be stupid and tell the truth.

I got some more screens and re-milled all my BP

I granulated as usual and dried as usual. Then I combined all into a single lot as before. Here comes the juicy part- I used to use as is- that is anything that passed 4 mesh from Cannon powder to prime! It did work but varied a lot. It wasn't the milling or type of charcoal or drying it was not understanding the need to grade the final BP. Somewhere I got the idea for flame propagation there had to be air space between granules. But not interplanetary! I know I MISSED a very basic part of making BP. Now it is all graded to actual 2FA and 4FA, 5FA.

I have not baseball tested yet but I made a report with the 5FA the size of an m-80 and it with a little confinement actually made a decent report instead of just pushing out the end plug. A basic but very important part of the process I overlooked. Lesson forever learned. Feel free to laugh or think - what an idiot!

[lloyd]

No... "what a student". Everyone must learn. Some of the "obvious stuff" isn't obvious.

 

Good luck!

 

Lloyd

[memo]

Lloyd and I are the same age, the big diff is I started making my own about a year ago, the bombs don't count.

 

memo