Shell question on fusing and burst charge

[Merlin]

I have been crossmatching and tying both ends of the time fuse with visco. It has always worked. However, tell me if I am wrong. I am thinking of crossmatching the outside time fuse( lift charge end) as usual but on the inside since I only make 2 to 3 inch shells I am thinking of making a change. First I dont get the best breaks. Ashamed to say not as good as commercial 1.9 shells. So I am thinking on the inside of the shell instead of cross-matching--- cutting the time fuse at an angle and priming with NC/ meal then tying a small baggie of 70/30 say about 3 or 4 grams onto the time fuse. Then adding the stars and burst charge in the shell surrounding the central flash bag. Is this a stupid idea?

I cant see tying a crossmatch inside a flash bag. Anyway I know there is the bright flash when it goes off but other than that should this work? Thought I would ask before doing it.

P.S. Here in Alabama this time of year vegetation is dead and we have not had the usual rain so I don't dare test anything until it does rain (fire hazard). In summer not a problem. But when it does rain I want to be ready to test.

Edited November 30, 2014 by Merlin

[Jakenbake]

IMO 3-4 grams of 70/30 flash is going to blow that little shell blind big time. I would suggest making a passfire to light the BP charge in the center.

[braddsn]

Couple of things Merlin. First... everything I mention here is based on my personal experience and opinion.. so your mileage may vary. I have shot maybe 50 or 60 4" shells and have not crossmatched one of them. All of them have bursted perfectly. The method I use is as follows. Right before I tape the lift bag to the bottom of the shell, I use a razor blade and split the time fuse down the middle, about 1/4", then use the blade to sort of pry it apart so it's open kind of like a duck's bill would be open. Then I carefully push it down into the lift bag so that it's in direct contact with the lift bp. I can just about guarantee you that you will have 100% success doing this. IF you have a method of crossmatching down that is easy and doesn't take much time, by all means go for it if it makes you feel better. But for me, I have yet to have a shell fail, and it is quick, simple, and doesn't require any extra fuse/string, etc. Also note, I don't split the fuse with the blade until right before I plunge it into the lift bp. I don't want any of the fine bp that is inside the fuse to spill out everywhere. . As far as your breaks, here is what I suggest. Firstly, dump the flash powder idea. LIke Jake said, 3-4 grams of flash is going to trash your stars before they even get a chance to light. You will just have a small salute shell. Your solution I believe is going to be to use KP burst instead of BP burst. Shimizu states in F.A.S.T. that in smaller shells (shells under 8"), KP burst is the way to go. Personally, I am having good luck with regular (bp on rice hulls) burst in my 4 inchers. BUT, if I were having any issues at all with soft breaks, I would simply convert to using KP burst, and I believe that would solve it. I have not used KP burst, but from what I have read and what some folks on here have told me, KP burst is quite a bit more potent, especially with small shells. KP burst is 70% Potassium Perc, 18% Charcoal, 12% Sulfur, and 2-5% Dextrin. Give that a try, I would bet your problem will go away.

[eb11]

I went to pass fire on the time fuse and bprh in the center look up how bangcock pyro builds his shells in the member tuts

[dagabu]

I have been crossmatching and tying both ends of the time fuse with visco. It has always worked. However, tell me if I am wrong. I am thinking of crossmatching the outside time fuse( lift charge end) as usual but on the inside since I only make 2 to 3 inch shells I am thinking of making a change. First I dont get the best breaks. Ashamed to say not as good as commercial 1.9 shells. So I am thinking on the inside of the shell instead of cross-matching--- cutting the time fuse at an angle and priming with NC/ meal then tying a small baggie of 70/30 say about 3 or 4 grams onto the time fuse. Then adding the stars and burst charge in the shell surrounding the central flash bag. Is this a stupid idea?

I cant see tying a crossmatch inside a flash bag. Anyway I know there is the bright flash when it goes off but other than that should this work? Thought I would ask before doing it.

P.S. Here in Alabama this time of year vegetation is dead and we have not had the usual rain so I don't dare test anything until it does rain (fire hazard). In summer not a problem. But when it does rain I want to be ready to test.

 

Interesting that the visco took fire on the other side, it should be somewhat resistant to side fire. Black match is normally used for cross matching on both ends.

 

Slurry and angled cutting is done all the time on small chinese shells, most serious hobbyists use black match for cross match and certainly on larger commercial shells. The only thing I will snip-n-slurry is timed inserts, anything else gets cross matched or a spolette.

[dynomike1]

Think about this. You put all this time into building this shell, do you want a possible failed shell because of a short cut? i use an ice pick to make a hole for my crossmatch. 2 things if you are using plastic, make sure you get a good weld on the seam, also make sure the crossmatch is in the center of the shell. 2g. of 70/30 max on a 3" shell. If you are using color stars they will have to be primed.

Edited December 8, 2014 by dynomike1

[Merlin]

 

Interesting that the visco took fire on the other side, it should be somewhat resistant to side fire. Black match is normally used for cross matching on both ends.

 

Slurry and angled cutting is done all the time on small chinese shells, most serious hobbyists use black match for cross match and certainly on larger commercial shells. The only thing I will snip-n-slurry is timed inserts, anything else gets cross matched or a spolette.

you are right about visco taking fire from the side. But it has worked everytime. The packaging on the visco says "visco crossmatch". It is very thin compared to regular safety fuse visco. Anyway I envisioned tying the central flash bag around the inside time fuse and if crossmatched that would be difficult. I am only making 3 inch or smaller shells. I was going to glue the stars to the sides of the shells dump some more on that and use BP to fill the spaces I thought 2-3 grams of flash type powder right in the middle would result in a more symmetrical break. I know pasting correctly is also important. However, I just dont have the dexterity to spike such small shells with string hence the central flash bag idea.

[Merlin]

Couple of things Merlin. First... everything I mention here is based on my personal experience and opinion.. so your mileage may vary. I have shot maybe 50 or 60 4" shells and have not crossmatched one of them. All of them have bursted perfectly. The method I use is as follows. Right before I tape the lift bag to the bottom of the shell, I use a razor blade and split the time fuse down the middle, about 1/4", then use the blade to sort of pry it apart so it's open kind of like a duck's bill would be open. Then I carefully push it down into the lift bag so that it's in direct contact with the lift bp. I can just about guarantee you that you will have 100% success doing this. IF you have a method of crossmatching down that is easy and doesn't take much time, by all means go for it if it makes you feel better. But for me, I have yet to have a shell fail, and it is quick, simple, and doesn't require any extra fuse/string, etc. Also note, I don't split the fuse with the blade until right before I plunge it into the lift bp. I don't want any of the fine bp that is inside the fuse to spill out everywhere. . As far as your breaks, here is what I suggest. Firstly, dump the flash powder idea. LIke Jake said, 3-4 grams of flash is going to trash your stars before they even get a chance to light. You will just have a small salute shell. Your solution I believe is going to be to use KP burst instead of BP burst. Shimizu states in F.A.S.T. that in smaller shells (shells under 8"), KP burst is the way to go. Personally, I am having good luck with regular (bp on rice hulls) burst in my 4 inchers. BUT, if I were having any issues at all with soft breaks, I would simply convert to using KP burst, and I believe that would solve it. I have not used KP burst, but from what I have read and what some folks on here have told me, KP burst is quite a bit more potent, especially with small shells. KP burst is 70% Potassium Perc, 18% Charcoal, 12% Sulfur, and 2-5% Dextrin. Give that a try, I would bet your problem will go away.

Thanks KP is worth a try. I cant imagine a 8 inch shell. I am only doing 1.9 to 3 inch shells. Thanks for your advice. I have some KP on hand.

[dynomike1]

I guess i am a little confused. Are you shooting ball or canister shells? I don't use flash bags, i might start using them on canister shells. On ball shells i just sprinkle some on both hemis. If i read the first thread right you are cross matching 1/8" Visco?

Edited December 8, 2014 by dynomike1

[Merlin]

I use ball shells #1 paper. #2 Plastic. I have tried canister but they dont break so well for me.