dynomike1 Posted January 7, 2013 Share Posted January 7, 2013 I know i am probably going to get jumped plastic vs paper but i got plastic shells that i got to use. Well i finely shot the other night and the next day when i went and got my tubes i was looking around and i noticed a lot of half shells ( fuse half) laying there,instead of breaking they were coming apart at the seam. I glued them with PVC glue and some were also wrapped with 6 layers of masking tape and or reinforced tape. Since i made those I've found that i should have been using Xylene. Am i headed in the right direction? Cant find much info on finishing plastic shells. I sure would appreciate the help. Link to comment Share on other sites More sharing options...
TritonPyro Posted January 7, 2013 Share Posted January 7, 2013 Hi D. I have after years got into firing a 2 inch mortar. Using my powder and a ball, I got great height. Trying later with a small ball shell ( given too me ) the powder flashed past the ball I guess and ignited it. I have some plastic cylinder shells and my test one with a clip on powder container was great. Is this the norm? Thanks for your help. Link to comment Share on other sites More sharing options...
psyco_1322 Posted January 7, 2013 Share Posted January 7, 2013 I used to use PVC glue, never had an issue. Super glue also works great, but some people to use xylene. What seems to give good results is pasting the plastic shell with paper after you glue it shut. If they are 2" shells, it probably wont make much difference, but if they are bigger, it might help your breaks. Link to comment Share on other sites More sharing options...
dynomike1 Posted January 7, 2013 Author Share Posted January 7, 2013 I guess i forgot to state these were 3 & 4". Here is a picture of one that i found. Link to comment Share on other sites More sharing options...
chemtech89 Posted January 9, 2013 Share Posted January 9, 2013 What are you using for your break charge? Adding a booster will help a lot with the issue your having. I haven't had this specific issue but before I started using boosting for plastics, I would find large pieces laying around and never found a piece of the top and bottom hemispheres still connected with glue. So the center is still relatively a weak point. Also, Ive read Xylene and Acetone with basically weld the two hemispheres together so this should help as well. Ive never used those solvents but am planing on it the next time I make plastic shells. I quickly stopped using PVC cement because I felt it wasn't doing what other glues could. I have been using Gorillas super glue and that seems to work well, but is more expensive compared to the solvent idea. Try using the 3 strip method show on the link below, its from skylighter. This give much more assurance the shell shatters instead of just separating. The booster and tape method also helps with symmetry... which is tough with plastic as you probably know. I strongly agree with what psyco_1332 said about pasting. Skylighter also has a write up about this called Hybrid shell building or something similar. http://www.skylighter.com/fireworks/how-to-make/basic-3-inch-plastic-ball-shells.asp Link to comment Share on other sites More sharing options...
dynomike1 Posted January 9, 2013 Author Share Posted January 9, 2013 (edited) I'm using BP for break. I got some Xylene today $18.00 a gal. @ Home Depot and glued the half in the picture with another half i found and hit it 3 times with a hammer well it did-int come a part at the seam it broke so glue was probably some of my problem. I guess i need to try a different break also. It's hard to tell but that shell in the picture was pasted.Yea Harry is calling for PVC that's where i got that from. I think most of his stuff is for starters you know it is easier to modify than it is to design, at least for me. You know i read all the different cans of PVC must of been 6 or 7 and all of them had the same ingredients. Edited January 9, 2013 by dynomike1 Link to comment Share on other sites More sharing options...
pyrojig Posted January 9, 2013 Share Posted January 9, 2013 (edited) I too use plastic shells and find that a more energetic burst is required to get a nice break .. I use about a gram or two (of flash or whistle)for 3" and 3-5g for a 4". The same goes for whistle . I prefer to coat my bp rice hulls with a nice dusting of the whistle for a booster effect. This is usually mixed in a tub, and then placed into the hemis after the stars are loaded.Strapping tape is a need as well. I do the 3 axis method, and finish with a layer of masking / or pasting for a beauty layer on the 4" and build the 3" up a few more layers due to the small dia plastic hemis. Edited January 9, 2013 by pyrojig Link to comment Share on other sites More sharing options...
yvariro Posted January 9, 2013 Share Posted January 9, 2013 (edited) Hi Dynomike,i think this is your burst charge that is the main problem,bp is a ballistic powder so that is normal that your hemis just separate in 2 part,but how was the bursting of your stars? I've bought 3" and 4" hemi too,and i will use them soon, si i must buy strapping tape and super-glue? or gummed tape will do the job? Edited January 9, 2013 by yvariro Link to comment Share on other sites More sharing options...
Potassiumchlorate Posted January 9, 2013 Share Posted January 9, 2013 H3 or KP will do the job. Link to comment Share on other sites More sharing options...
dynomike1 Posted January 9, 2013 Author Share Posted January 9, 2013 The stares looked like some blew blind couldn't really tell they were all bunched up. As for the strapping tape the hemi in the picture had 4 layers on it plus 3 layers of Masking tape. I may try to build a shell today and test with Xylene, Looks like if you don't get a good glue on the seam, tape is not going to do it by it's self. Those were the first stars and shells i made, so i got rid of everything now it's time to start over. I am going to try BP burst again if i cant get it right i will go to a stronger burst. I am still waiting on the vidieo where i can tell more about it. Link to comment Share on other sites More sharing options...
Mumbles Posted January 9, 2013 Share Posted January 9, 2013 I've never understood the PVC cement thing. The shell casings themselves are usually polystyrene. It never really made sense to me to be adding a different plastic into the mix. When I was doing plastic shells, I used Toluene with some broken shell pieces dissolved in it to make it more viscous. One thing to keep in mind with toluene and xylene is that they take much longer to dry than something like acetone or methylene chloride. Wait until the joint lacks the solvent odor. The toluene solvent did get my shells breaking better. Most people do eventually move into all paper construction. It's cheaper in the long run, more ecologically friendly, and most will agree that the performance is typically better and more adjustable. Link to comment Share on other sites More sharing options...
dagabu Posted January 9, 2013 Share Posted January 9, 2013 MEK works well too, it dries in between the ones mentioned above. -dag Link to comment Share on other sites More sharing options...
dynomike1 Posted January 9, 2013 Author Share Posted January 9, 2013 Looks like to me PVC is to thick to get between the halves. From what i can see when i put the hemi's together they pushed the glue back out. Link to comment Share on other sites More sharing options...
dagabu Posted January 9, 2013 Share Posted January 9, 2013 Looks like to me PVC is to thick to get between the halves. From what i can see when i put the hemi's together they pushed the glue back out. That and it takes WAY too long to dry, making the shell rubbery... -dag Link to comment Share on other sites More sharing options...
dynomike1 Posted January 9, 2013 Author Share Posted January 9, 2013 I built a 4" today same as Dave Stoddard builds his 6" using Xylene maybe tomorrow well see. Hopefully i'll get a video.I'm going to try to do it @ dusk. Link to comment Share on other sites More sharing options...
dynomike1 Posted January 21, 2013 Author Share Posted January 21, 2013 I shot my 1st. shell since i started this thread, last night. I used Xylene instead of PVC glue got a pretty symmetrical break had my son and grand kids 4mi. away watching and my wife videoen and after my two misfires i'll be dam i was the only one that saw it. That was a 4", i am making two 3" for tonight. Link to comment Share on other sites More sharing options...
FREAKYDUTCHMEN Posted January 22, 2013 Share Posted January 22, 2013 Plastic shells need to dry at least one or 2 days, always, no matter what kind of solvent you use. Link to comment Share on other sites More sharing options...
dynomike1 Posted January 22, 2013 Author Share Posted January 22, 2013 Well i shot two 3" yesterday Xylene dried about 4 hrs. i couldn't ask for a better break. But longer drying time isn't going to hurt. Link to comment Share on other sites More sharing options...
chemtech89 Posted January 22, 2013 Share Posted January 22, 2013 That sounds great any videos? Are you still using the hybrid method(pasting on top of the plastic). If you are how many layers are you using? Link to comment Share on other sites More sharing options...
AirCowPeacock Posted January 23, 2013 Share Posted January 23, 2013 I find with xylene plastic shells dry fully in just a few hours. I'm interested in this hybrid method, I might try it out some time. Link to comment Share on other sites More sharing options...
DanielC Posted January 26, 2013 Share Posted January 26, 2013 Sooner or later everyone makes the move to paper shells, but truth be told many of us started with plastic shells. I still have a bunch of them lying around.They are so fast to make, and are great for testing stars in the air. Using a booster will help much, especially for the smaller shells.Extremely hot BP makes for a better break even if it isn't really necessary for lifting. One thing I didn't see anyone touch on was that some plastic shells are vented and some are not. The ones I've got have a hole in top hemi that a lift ring is glued into after the shell is cured out.The solvents will sometimes expand and make pin holes in the joining line making it very weak and can lead to a flowerpot as well.For smaller shells I use granulated hot BP not rice hulls. Just adding my 2 cents...hope it helps some Link to comment Share on other sites More sharing options...
AirCowPeacock Posted January 26, 2013 Share Posted January 26, 2013 I have a few plastic shells still lying around. I use em occasionally for areial salutes and measuring cups. Link to comment Share on other sites More sharing options...
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