Fireworks.org – The World’s Fireworks Community › Forums › Pyro Technology › Any tips on getting a cleaner break on 4 inch shells?
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I’ve been working on 4″ canister shells and I keep getting uneven breaks. Using BP lift and rice hulls for the break charge, but the pattern’s never as round as I’d like.
Anyone have tips on getting that perfect symmetrical break? Timing? Amount of flash? Would really appreciate any advice.
Check your pasting consistency first. Uneven paste layers can cause weak spots that blow out before the rest of the shell. Also make sure your spiking is even. I had the same problem until I started being more careful about symmetrical spiking.
What’s your burst charge composition? I’ve found that switching to a 70/30 KP/AL mix gave me noticeably cleaner breaks compared to straight BP. Less smoke, more pop. Takes some fine tuning but worth the effort.
I had the same issue with my early shells man. Took me a while to figure out it was my pasting technique all along. I was rushing the layers and getting weak spots.
Something that helped me a ton was switching to a hemp string for spiking instead of cotton. Way less stretch, tighter wrap. Also started using a break charge of 60/40 KNO3/sulfur with 5% aluminum ? gives a real crisp crack instead of a puff.
One more thing ? check your lift charge too. If you’re not getting consistent height your break position will be all over the place and the pattern will look uneven no matter what.
What mortar tube length are you using? I found 4:1 ratio (4x diameter) gives the best results for canisters.
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