14 replies to this topic

[frosty90]

Hi all,

I would like to build some 2" ball shells and for timing I am thinking of using spolletes (I cannot get visco or commercial time fuse). What concerns me though is putting the spollette directly in the lift cup; is this the done thing? Ive seen on larger shells the spollette is on the top of the shell. Is the lift for a 2" shell likely to blow through a spollette?

Cheers,
Jesse

[cooperman435]

from experience Ive bottom fused 4" shells with large diameter spoolettes and had only one or two blowthroughs.

I was using slightly thinner walled tubes than I now know was ideal so this is the likely cause as the powder was not as compact as could have been achieved with thicker walled tubes.

on small shells like 2" bottom fusing will not be a problem in my opinion

[Atom Fireworks]

Hi Frosty,

I have been at it for 3 or 4 months now making 2 and then 3 inch shells, I have only had 1 flower pot ( shell goes off in tube upon launch) and that was down to me not glueing the time fuse in properly, Bottom fusing should be fine as far as 2,3 and 4 but ime no expert quite the newbie. On cylindrical shells u may wanna fuse them on top as from what ive read and heard they are not as strong as a spherical shell due to the nature of the shape with a big bottom flat end to take the shear force of the lift .

Dumper

[frosty90]

Thanks for the answers guys.

I was reasonably confidant it would be fine anyway, but I'd just thought I should get some others opinions before I fired it. I did end up firing it tonight, my first shell! Wooo! Everything went well, the spollete timing was perfect, but the break wasnt strong enough. Oh well, I though it was good for my first one. too bad the vid camera's batteries went flat just after I lit the fuse .


Another thing, On new years, after seeing someone elses display, as their shells went up, they often did a sort of spiraly sort of movement (if that makes sense), as if the shell was spinning on a horizontal axis, and the spollete was off center. Tonight I noticed my shell did the same thing. It was a nice effect, but why the hell should they be leaving the tube spinning? like a bullet in a barrel with rifleing?

Cheers,
Jesse

[seymour]

There is no one thing that reliably causes the spinning that I am aware of, but the effects of how the lift is attached, debris from quickmatch that has just burnt, and other 'imperfections' will be sufficient to cause the spinning. As far as I am aware the spinning will be random, with some spinning faster than others on different planes of rotation, however considering how large multibreak canister shell builders can controll the spinning, even preventing it to an extent the randomness could well be limited.

[Atom Fireworks]

Yea i agree the spinning is random the shells size is not going to be a 100% sphere so it will be imbalanced, i have fired a few commmercial shells and looked inside the tubes afterwards ( tubes were brand new) and you could see the corkscrew effect inside the tube in the charedness, this was totally random between tubes. What are you using to break your shell and what size are your shells, i burst 3 inchers with bp coated rice crispies and get a nice burst similar to commercial's.

Dumper

[Arthur Brown]

Spolletes blowing through largely depends on the quality of the product! It's commercially normal to bottom fuse ball shells to 4" or 6" but normal to top fuse all cylinder shells.

Spollettes for small (sub 3") shells may when burned be too big a vent for the burst to go well, that's a good reason to use time fuse or wrapped visco.

As to spinning it's a feature or a problem but without some flight control shells will spin, Balls will spin any way, cylinders will rotate on axis until they slow, then they start to topple also.
It's normal to leave a drag cord attached if you need to prevent toppling, but nothing will prevent axial rotation.

It's the rotation that messes shape shells -cat face, smiley face, heart etc and the reason why more symetric shapes are nice, cube, orbital, ring etc

[frosty90]

Hi,

Hey dont get me wrong! Im not complaining about the spinning, it looks very cool, and makes an interesting sound too!

Spollettes for small (sub 3") shells may when burned be too big a vent for the burst to go well, that's a good reason to use time fuse or wrapped visco.

Hmm yes I didnt think of that... My spollettes are about 8mm inner diameter, probably a little large for a 60mm shell I suppose? But it is a bit fiddely to make them much smaller. The only problem is I cannot get visco or commercial time fuse where I am, and I dont like the idea of trying to use blackmatch to fuse shells! when i say the break was no good, it may have been simply that the stars blew blind or shattered, it did produce a fairly loud report, the stars were chrys. 6, and there was alot of orange sparks/fire dust produced.....oh well it all comes down to experimentation and fine tuning I suppose.

BTW: I am using granulated BP with a tiny bit of Al/S/KNO3 'flash' in a little tissue paper baggie to burst the shell. The stars are paked inbetween with more granulated Bp

Cheers,
Jesse

Edited by frosty90, 06 January 2010 - 01:33 AM.

[Atom Fireworks]

Hi,

Hey dont get me wrong! Im not complaining about the spinning, it looks very cool, and makes an interesting sound too!



Hmm yes I didnt think of that... My spollettes are about 8mm inner diameter, probably a little large for a 60mm shell I suppose? But it is a bit fiddely to make them much smaller. The only problem is I cannot get visco or commercial time fuse where I am, and I dont like the idea of trying to use blackmatch to fuse shells! when i say the break was no good, it may have been simply that the stars blew blind or shattered, it did produce a fairly loud report, the stars were chrys. 6, and there was alot of orange sparks/fire dust produced.....oh well it all comes down to experimentation and fine tuning I suppose.

BTW: I am using granulated BP with a tiny bit of Al/S/KNO3 'flash' in a little tissue paper baggie to burst the shell. The stars are paked inbetween with more granulated Bp

Cheers,
Jesse

Do you use a ball mill to make your bp meal? if not get one and if you do then a decent meal coated onto rice crispies will be fine, i didnt believe it until i tried it and now i wouldnt use anything else i dnt even use a booster. You use much less meal powder than you do when filling them up with granulated lift, its granulated to grade it ad get diferent burn speeds, if you coat rice crispies then theres more surface area ( i think) and thats why they burn rapidly thus being great for breaking shells.

Dumper

[ToFe]

For a small shell, if you where to ram a plug in spollette then drill a hole through the side like you would for time fuse then pass black match though the hole. Would this allow enough pressure to build up in the shell?

I have used blackmatch for bomlets however the result has been very mixed and then normally don't catch did not prime them with prime.

I total agree with covering a medium with bp instead of granulated for infill.

[Vic]

Hi all,I would like to build some 2" ball shells and for timing I am thinking of using spolletes (I cannot get visco or commercial time fuse). What concerns me though is putting the spollette directly in the lift cup; is this the done thing? Ive seen on larger shells the spollette is on the top of the shell. Is the lift for a 2" shell likely to blow through a spollette?Cheers,Jesse

If you are worried about the hole lot blowing through rather than just the powder core you can rap glued string around the base of the spolette were it meets the shell, to make a reinforcing fillet and fire block,much the same method as used sometimes on standard time fused shells.

[seymour]

For a small shell, if you where to ram a plug in spollette then drill a hole through the side like you would for time fuse then pass black match though the hole. Would this allow enough pressure to build up in the shell?

That would probably work, but a slightly easier method (though the difference is slight) would be to drill in to the clay plug, much like a rocket's passfire.

[Mumbles]

Why not just roll thin ID tubes for small shell spolettes. 1/16 to 1/8" should be fine. There are other ways to modify spolettes. They're usually used for very short timings where the lift of break could burn through, and not keeping pressure on the inside. I've never heard of there being too big of a hole in small shells before, but it makes sense. You can back drill the spollette. Ram the powder train maybe 6-8mm longer than you want, and drill it back to where you want it. This gives both a big flash of flame inside the shell, and keeps good strength. Alternatively you can press a short clay plug on top of the powder train, and drill through it into the powder train. This would also provide some strength and pressure inside the shell.

[frosty90]

Why not just roll thin ID tubes for small shell spolettes. 1/16 to 1/8" should be fine. There are other ways to modify spolettes. They're usually used for very short timings where the lift of break could burn through, and not keeping pressure on the inside. I've never heard of there being too big of a hole in small shells before, but it makes sense. You can back drill the spollette. Ram the powder train maybe 6-8mm longer than you want, and drill it back to where you want it. This gives both a big flash of flame inside the shell, and keeps good strength. Alternatively you can press a short clay plug on top of the powder train, and drill through it into the powder train. This would also provide some strength and pressure inside the shell.

Ive made a couple of shells now with smaller id spollettes, I'll see how it goes. I think maybe more of a problem was not enough filler in the shell to ignite the stars, it was difficult to tell what happend, the shell definitely blew, there was a loud report, but either the stars blew blind or shattered, or the shell didnt pop hard enough.

This gives both a big flash of flame inside the shell

Ive just been loading a small amount of loose powder in the end, then stuffing a few pieces of blackmatch in there, on the ground it blows a big fireball out the end.

Cheers,
Jesse

[Mumbles]

Yeah, I pack the end of my spolettes with blackmatch too. I guess that part is a moot point.