12 inch shell

[pyroguy1960]

So I think I'm going to tackle building a 12" shell soon, was going to do a simple gold streamer, probably that hardt comp that worked out in the 8". I've been searching around trying to get the lift requirements for a shell this size and haven't really come up with much. I have a buttload of goex 2FG and that's what I'll probably use to lift this as I don't really trust my homemade 2FA that much.

 

What you reckon around 8oz of 2FG with and around 5-6 seconds on the timefuse?

[ExplosiveCoek]

So, you're going to build yourself a 12'' shell but you can't make decent lift powder..? Way to go!

 

I really don't get it.

 

What is the weight of a 12'' shell? I'd suggest something in the range of 7-8% for lift depending on the power of your lift.

[dagabu]

7 seconds for the time fuse and as "a rule of thumb frequently used for lift charge calculation is one ounce of 2FA for every pound of shell weight up to 10 lbs, and 1/2 oz of lift for each pound in excess of 10 lbs. The larger the shell is, the more factors such as mortar length, shell length and shell clearance come into play."

 

Also, with 2Fa, you should get a real nice flower pot, the grain size is way different, 2Fg is 16-30 mesh and 2Fa is 4-12 mesh. In larger shells, you want the more gentle lift.

[pyroguy1960]

I can make lift powder and have, it's just not a strong as goex. I only use it for my 4" shells. Not sure what it's going to end up weighing yet either.

 

If you ask me making lift powder is not a rudementary skill (I know everyone says it is the first thing you should learn to do well), however in my experience it requires the right charcoal and ball milling and is generally a pain in the ass. I hobby pyro can make many devices without making his own powder.

[pyroguy1960]

Also, with 2Fa, you should get a real nice flower pot, the grain size is way different, 2Fg is 16-30 mesh and 2Fa is 4-12 mesh. In larger shells, you want the more gentle lift.

 

I think you meant "with 2FG"

 

I've lifted about 20 8 inch shells with 2FG and not one of them flowerpotted, you simply use less powder no? Many of the large commercial shells I've disected don't use 2FA either....

 

I found the 2FG to be really economical, I only have to use about .75 oz for a 4" , 4 oz. for a 8". So basically half of what I would have used for 2FA. Best game going if you ask me, beats hours of balling milling and pressing and corning pucks. I'd rather spend my pyro time elsewhere.

Edited December 1, 2010 by jms04081974

[Mumbles]

I don't know if I would go as low as 8oz. A 12" shell will probably weigh in the neighborhood of 20lbs or so. I would go with maybe 12oz. The ounce per pound rule is designed for canister shells, and was based off of older Goex, which was stronger than current Goex.

[dagabu]

I think you meant "with 2FG"

 

I've lifted about 20 8 inch shells with 2FG and not one of them flowerpotted, you simply use less powder no? Many of the large commercial shells I've disected don't use 2FA either....

 

I found the 2FG to be really economical, I only have to use about .75 oz for a 4" , 4 oz. for a 8". So basically half of what I would have used for 2FA. Best game going if you ask me, beats hours of balling milling and pressing and corning pucks. I'd rather spend my pyro time elsewhere.

 

Consider yourself lucky that you haven't had bad breaks, the Fg provides a much higher shock to the shell and can shatter stars and break the shell in the gun. I don't know of any large shells that are lifted with 2Fg.

Edited December 1, 2010 by dagabu

[pyroguy1960]

Weird, I never knew that, I took apart an 8" commercial shell a few months ago and the grains looked in the 3FA-4FA range to me...

[dagabu]

Weird, I never knew that, I took apart an 8" commercial shell a few months ago and the grains looked in the 3FA-4FA range to me...

 

A light weight shell like a pattern shell may survive the lift but a double petal or zinc star shell would get a beating.

 

Mumbles, you have access to your books, what size is 2Fa recommended for? I think 4" and up are lifted with polverone or 2Fa.

[Mumbles]

Well, it's recommended for pretty much everything, but I tend to use it for 4" an up. Under that, 4FA seems to be needed to get a little extra oomph. I also use 4FA if I am shooting in the cold for some 4" shells.

 

The chinese have shown you can get away with finer lift in bigger shells. I think even those cheapskates use 2FA on 12" shells though. You also have to remember that while they use finer lift, they also tend to over lift their shells with crappy powder. They don't really use less overall powder, but trying to use similar sized good quality grains will require a decrease, and potentially risk flower potting shells. I've always thought most of the problems with chinese shells came from blowing up guns. I'd much prefer (a non-salute) flower pot to a muzzle or low break, or a blown racked gun.

[pyroguy1960]

Is cannon grade goex equivalent in strength to wano 2FA? The local gun shop sells cannon as well.....I could use that...

 

I have yet to find a charcoal that produces suitable homemade powder. I've tried commercial airfloat & some softwood pine. The pine powder was about half the strength of goex. Has anyone tried that willow charcoal that Hobby Chem Supply sells?

[Fly]

Is cannon grade goex equivalent in strength to wano 2FA? The local gun shop sells cannon as well.....I could use that...

 

I have yet to find a charcoal that produces suitable homemade powder. I've tried commercial airfloat & some softwood pine. The pine powder was about half the strength of goex. Has anyone tried that willow charcoal that Hobby Chem Supply sells?

 

It's not hard to make powder faster than Goex.You can make very strong powder out of white pine if you

don't have anything else.A few questions!What kind of ball mill do you use?How much media do you fill

your drum with?

 

I think most people go wrong not using enough media & think they must mill for 24 hours.I mill mine in

two to three hours.When I used a Harbor freight mill time was about six hours.

[pyroguy1960]

I use a thumblers tumbler mill, it has an octagonal lined barrell, I fill it almost halfway with .50 cal lead balls, then for the charge I pour enough in to just cover the media, then I shake it around a little to settle it, then I fill a little more so the final charge is about a 1/2 inch above the media. So basically half of the barrell is unfilled with anything (open space).

 

When I first did a BP batch I ran it for two hours, but when I opened it up almost all the powder had caked up on the bottom already and I could tell instantly that it had long since been done. So now I only run it for about an hour and when I open it the powder is just starting to stick to the sides.

 

Then I take a wolter 3 1/2 inch comet pump, wet the meal with about 7% water and press 1/8-1/4 inch pucks with all the strength of a 12 ton shop press, I let the press dwell for about 5 minutes and them pump up the pressure again as much as I can. I let the pucks dry for about a week and then smash em up in a ziplock bag with a mallet and screen the results.

 

The only thing I can think of is I don't have any courser screens than 20 mesh at the moment as I had broken my course ones by accident. So I've been corning through 20 and take what sits on 30 to use. So I haven't actually tried that pine in a 2FA granulation. I have a 6 & 12 mesh screen on order. But the 20-30 mesh should still be powerfull powder no?

[Mumbles]

I would start to run the mill longer than an hour. If you break up the clumps it will continue to mill. I used to be able to tell by the noise of the media if it was clear, partly, or fully caked. You can start beating on the outside of the jar even while it is turning to break up the clumps. I prefer to take them off though. I used to break it up with a butter knife. In small 3lb tumblers, it would cake when it was done, but with my larger jar it would cake too fast, and not let everything get ground up enough. In a way, this was the root cause of my accident.

[Peret]

The advantage of commercial lift isn't the quality of it so much as the consistency. When I make a batch of shells I want to know they're going to the height I expect, not flop in front of me fizzing nor go into orbit. I can accept variability in bursts and mines, it makes life interesting, but not in lift. Sometimes my powder's pretty good, occasionally not so good, and I haven't got time to calibrate test shots whenever I make a new batch of BP, so I always use commercial lift. Cost-wise, even if I value my leisure time at only minimum wage, by the time I've mixed it, milled it, corned it, dried it and sorted it, commercial still wins.

[pyroguy1960]

I would start to run the mill longer than an hour. If you break up the clumps it will continue to mill. I used to be able to tell by the noise of the media if it was clear, partly, or fully caked. You can start beating on the outside of the jar even while it is turning to break up the clumps. I prefer to take them off though. I used to break it up with a butter knife. In small 3lb tumblers, it would cake when it was done, but with my larger jar it would cake too fast, and not let everything get ground up enough. In a way, this was the root cause of my accident.

 

 

Another reason why I don't like 3 component milling of BP, I run it out in the woods 200 feet away from anything and it's surrounded by two large bolders on either side and a wood pile each of the exposed sides. I start and stop it remotely and am not comfortable at all shaking it around or messing with it while it's running. I know the risk isn't that great, but it seems like I'd only have to be unlucky once. Now I'm really worried if some as experienced as you mumbles can have a milling accident, I feel like I'm really pushing my luck here.

 

I have to say I agree with peret 100%, if it's one thing I always want to work perfectly everytime it's my lift powder. Even if I was able to mill great powder, I don't think I'd ever trust it under 8 or 12 inch shells the consistancy just doesn't seem to be there. I did have one of my four inch shells break somewhat low using my own lift while others shot fine from the same batch.

 

I don't know it seems like so much added work and danger. Buying goex isn't that expensive at all so where's the benefit?

[Mumbles]

I didn't have a milling accident, but if my powder didn't cake so fast, it never would have happened.

[Fly]

Try drying your KNO3 by its self in the oven before milling, & see if that helps with caking.

 

Fly:rolleyes:

[pyrojunkie]

I'm curious why everyone seems to think the only way to get good powder is to press and corn it. I have never corned BP, and am getting very hot and consistant powder. I granulate with either red gum and alchohol, or dextrin and water. I use Alder coal, and mill for 3 hours. There is a good article on Skylighter describing the process.

[pyroguy1960]

That was the method I used on my first attempt to make powder, red gum & alc then granulate following that article. I had to throw away the powder it produced as it was so weak it was unusable. Must have been the charcoal....

 

 

[pyrojunkie]

It very well could be the charcoal. I think that the powder I'm making may be too hot for some things. I'm going to do some experiments with mixing the Alder with comercial airfloat to slow it down a little.

[Updup]

I'm curious why everyone seems to think the only way to get good powder is to press and corn it. I have never corned BP, and am getting very hot and consistant powder. I granulate with either red gum and alchohol, or dextrin and water. I use Alder coal, and mill for 3 hours. There is a good article on Skylighter describing the process.

 

I agree, I use pine 2x4's from construction sites, mill my BP for 3 hours and granulate it without dextrin (Now I'm using red gum, but I used to use no binder and it worked great), and I'm having great luck with my powder... Something dosn't seem right about your not being able to make good powder

Jms, how are you making your charcoal?

 

Also, I would say it takes me an hour of work per pound of BP I make... At minimum wage I would be able to buy 1/4 can of Geox, if that.

[pyrojunkie]

Up,

I just cut the wood into small pieces, and put it in paint cans and cook it on my gas grill right now. I plan on making a better system soon.

[pyroguy1960]

I haven't cooked my own charcoal yet, the only kinds I've used is commercial airfloat and that softwood pine from americanpyrosupply.com. Probably what my problem is.

 

I was under the wrong impression that 2FG could be used to lift anything which is why the goex has been somewhat economical for me. But if I have to start buying tons of cannon grade goex to lift the big shells, then yes it will get expensive.

 

It's getting cold in the northeast now, so I guess nows a good time to have a ragin charcoal cookin fire outside. Can I just use 2 x 4's from lowes? Or should I choose some other type of wood?

[dagabu]

Jms,

 

It seems that pyros take one of two paths, the one is the pyro that makes everything he can by hand, the hobby being the journey, not the destination. The other is the pyro that wishes to see what is at the end and is not as concerned with the craft side as much as the fire and enjoy side.

 

I dont fault you for being of the later but you will find that most of us here wish to take the journey step by step and not hurry too much.

 

I am making a 10# batch of pulverone this weekend, I will run two jars at a time and will listen to Car Talk and Wait, Wait dont Tell Me while they grind. In the end, the chems will cost me about $9.00.

 

That my friend, is the benefit.