ryanlg95 Posted March 27, 2012 Posted March 27, 2012 Im trying to make some cakes, and I have a source of mortar tubes and shell tubes that are the right size. I made a single shell by ramming bentonite in one end, then adding meal black powder, then cap the other end with more bentonite. The problem is fusing the shell, becasue no matter how small of a hole i drill into one end of the bentonite for the blackmatch fuse, when lit the shell doesn't explode, but all the gasses just vent out of the fuse hole. How can I fuse such a small shell (15mm outside diameter).Thanks in advance
PyroAce Posted March 27, 2012 Posted March 27, 2012 Im trying to make some cakes, and I have a source of mortar tubes and shell tubes that are the right size. I made a single shell by ramming bentonite in one end, then adding meal black powder, then cap the other end with more bentonite. The problem is fusing the shell, becasue no matter how small of a hole i drill into one end of the bentonite for the blackmatch fuse, when lit the shell doesn't explode, but all the gasses just vent out of the fuse hole. How can I fuse such a small shell (15mm outside diameter).Thanks in advance Theres a few other methods you can use. I like to use Plaster of Paris, just use the Plaster of Paris to form the plug, then push a scewer or toothpick or whatever that is the size for your fuse, push the fuse through the hole and gently push around the fuse to seal it. Don't make the Plaster too wet because this may effect the fuse. It's also good to leave a gap between the plaster and the end of the tupe, because you can put some colour composition in the cavity which looks great when the shells are going up.The only downside to this method is that if you are wanting to make your devices right then and there, because the plaster needs to dry you can't load it into your tube right away.
Pyrophury Posted March 27, 2012 Posted March 27, 2012 Im trying to make some cakes, and I have a source of mortar tubes and shell tubes that are the right size. I made a single shell by ramming bentonite in one end, then adding meal black powder, then cap the other end with more bentonite. The problem is fusing the shell, becasue no matter how small of a hole i drill into one end of the bentonite for the blackmatch fuse, when lit the shell doesn't explode, but all the gasses just vent out of the fuse hole. How can I fuse such a small shell (15mm outside diameter).Thanks in advance The clumping clay is usually rammed around the fuse in situ with a hollow rammer/former: http://www.amateurpyro.com/forums/topic/5223-bombettes-question/page__st__20__p__84800__hl__bombette__fromsearch__1?do=findComment&comment=84800
dagabu Posted March 27, 2012 Posted March 27, 2012 I second Pyrophury's recommendation, it works so much better. -dag
MikeB Posted March 27, 2012 Posted March 27, 2012 (edited) Im trying to make some cakes, and I have a source of mortar tubes and shell tubes that are the right size. I made a single shell by ramming bentonite in one end, then adding meal black powder, then cap the other end with more bentonite. The problem is fusing the shell, becasue no matter how small of a hole i drill into one end of the bentonite for the blackmatch fuse, when lit the shell doesn't explode, but all the gasses just vent out of the fuse hole. How can I fuse such a small shell (15mm outside diameter).Thanks in advance I see a few problems. Fusing, construction, and type of composition.If you are using BP as you said, you need very strong confinement and the composition should not be rammed, otherwise you are merely making a rocket. What you should be using is a KP-Al formula. Time fuse would be best suited but that depends on the construction technique. Visco can be used but is not as reliable. Black match can be used and a simple technique is to use sawdust to create a fire block and delay, what you would be making is a saetine. Whatever method you should make sure that the fuse is sealed well so fire does not transfer to the shell while still in your mortar or tube. One method using visco would be to make a base with a dowel plug approximately 1/4 inch tall whose diameter is the same as your tube. Drill a hole in the middle of the plug so visco can fit through it. The length of the visco extending will determine your timing. Make another dowel with a hole just larger than the visco, this will be your rammer. Carefully center the visco and place your tube over the plug, now ram an increment of clay. About 1/2 inch or a little more should work. Make sure there is about 1/2 inch of visco exposed on the inside and outside. Now fill the tube 3/4 full with your favorite vitamin F. Glue a plug in place on the top and then fill the recess with hot melt. Split the exposed visco into a fork down to the clay plug, dip it in a nitrocellulose meal slurry and then dip in grain powder to prime. This will give you a solid little report. see Pyrophurys link for some detail http://www.amateurpyro.com/forums/topic/5223-bombettes-question/page__st__20__p__84800__hl__bombette__fromsearch__1?do=findComment&comment=84800 Edited March 27, 2012 by MikeB
ryanlg95 Posted March 28, 2012 Author Posted March 28, 2012 Thanks for the help, but that does not help my problem of all the black powder just burning through the fuse hole, rather than exploding
Mumbles Posted March 28, 2012 Posted March 28, 2012 Compressed BP will nearly always burn like a jet. I don't know what else you expected. I take it you've heard of rockets, which are essentially compressed BP and a clay nozzle. If you describe the type of effect you're going for, we could probably help you in the right direction. It sounds like you're going for a salute type of effect.
ryanlg95 Posted March 28, 2012 Author Posted March 28, 2012 Well I'm not sure what effect I want to go for, I was just testing to see how to get the fusing right, because that's what always ruins what I make. I think I will have stars for my final product, but I was just testing fusing for now. I've seen some videos since I started this post, so I am learning.
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