Plastic hemis

[Tim1877]

Just wondering if there is any difference in the amount or type of break charge for plastic hemis vs paper. I'm making 3 and 4 inch shells.

[braddsn]

As far as amount, it's the same because you are placing the stars in the hemis and packing the rest of the empty space with meal coated rice hulls. It is nearly impossible to achieve the break symmetry and power of a paper (pasted) shell with a plastic shell. However, you can get somewhat close if you boost the break enough. Are you familiar with boosting with flash? Properly boosting shells and priming the stars that will go in these boosted shells is a bit of an art in itself. I would be glad to help you if you can give a little more info. How experienced are you? How many shells have you built? By the way, I noticed you are from Southern Illinois?? I am too! I work in Carbondale and live in Anna.

[dynomike1]

What do you mean close>LOL. Tim i can help you also, plastic is pretty much what i build. Like brad said we need more info. What solvent are you using, how are you putting them together. Every step you make could possibly change the effect of the break. Southern Ill. Now me and Brad have someone between us.

[Tim1877]

I live in west Frankfort and work in mt vernon I haven't actually made any shells yet getting ready to order some hemis. I have made decent lift powder it lifts a baseball high into the air I have coated some rice hulls as well any help or hints are greatly appreciated.

[braddsn]

Awesome Tim. You are close. If you need any help just let me know. I fired 360 shells last 4th of july ranging from 3" up to 8". This coming 4th I plan to shoot 400 or so.

[Arthur]

While you are right in saying the same amount of break is needed to fill the volume of a plastic or paper shell, usually the break is a very different mix. From three inches and up a paper shell is pasted to make the break hard enough to get good ignition and symmetry, with a plastic shell the break size and symmetry is only controlled by the booster put into the break charge.

[dynomike1]

While you are right in saying the same amount of break is needed to fill the volume of a plastic or paper shell, usually the break is a very different mix. From three inches and up a paper shell is pasted to make the break hard enough to get good ignition and symmetry, with a plastic shell the break size and symmetry is only controlled by the booster put into the break charge.

Good point

Are you reloading Brad or do you still have that many racks?

Edited December 7, 2016 by dynomike1

[mikeee]

I have seen some people use strapping tape on plastic shells to increase the strength of the shell

casing to provide for a better "break". Not a preferred method since you are adding more debris when

it falls to the ground along with the plastic shell casing. Paper shell casings will decompose within a year

or two and are easier to provide for a good break by adding appropriate layers of paper to the casing after

filling as needed.

[Arthur]

I dislike plastic hemis, they leave long life debris. Sometimes they are needed to barrier high humidity but not often.

 

The burst chemistry is totally different from paper shells, it's unlikely that a beginner would get both right first time.

[dynomike1]

Every time i put tape on mine it messes the pattern up. The trick to plastic is to get a good seal. I saw a video where carbon76 made the biggest 3" break i have ever seen with plastic.The only place i shoot is on my farm, usually the combine takes care of the debris.

Edited December 7, 2016 by dynomike1

[braddsn]

Mike I still have all the same racks I picked up with you. 160- 3 inchers, 80- 4 inchers, 24- 5's, 24- 6's, and 3- 8's.

[dynomike1]

I thought you might have got some 10's and 12's. I got 2 8" and 1 10". I have 79 total and it's all i can do to make enough shells for them.

Edited December 15, 2016 by dynomike1

[OldMarine]

Just received a care package of plastic hemis and want to put some up in the air on rockets. My 1" rockets will lift a 6" header to a good display height and I'd like to make a single petal with some 1/2" Ofca white stars I've not had occasion to use other than as single comets.

Reading here I've figured out that the MCRH I use in larger cylinder headings won't work for a good burst in a plastic one. Should I use a different burst or dust my hulls with Flash or Whistle?

[NeighborJ]

OM I use mcrh in plastic, it just needs a few pieces of fiber reinforced packing tape to give the extra confeinment. But flash works fine too. I use 6 pieces of tape across the shell to make A Star of David pattern on each end And one strip around the equator the tape only needs to be 1/2" wide. Edited December 16, 2016 by NeighborJ

[zan89]

save the nature and use papier ones...

[NeighborJ]

Do you like the OFCA white stars? I've just pressed a 1000g batch of 3/4" comets but that is the pearl. I took the remainder (750g) and mixed it with 1/2 silver wave then added 10% crackle. I'll be pressing that experiment today.

[OldMarine]

The Ofca white is very bright. The Spanish white was also recommended but I haven't tried it yet.

[NeighborJ]

I like the Spanish white, as well as the Gary Smith parlon white. The OFCA seems to burn slower but IDK they are not completely dry yet.

Almost all my hemis get that extra confeinment tape, even the paper shells. I am not against the use of flash but it's just something I avoid unless it's in very tiny shells,and even then I use an entire pasting layer of FRT before its pasted.

[Tim1877]

Has anyone every used KP for burst in plastic hemis?

[NeighborJ]

Yes Tim, the KP worked great and breaks hard. The only disadvantage I saw was that I couldn't dial in the burst. It could not be lessened like with the addition of flash can. I've never tried a mix of KP and bp,that may work.

[Mumbles]

You dial in KP burst shells with confinement (pasting usually). Plastic shells just don't have much confinement, thus why they're regularly burst with flash bags. I never got KP to work all that well in plastic even with pasting or strapping tape, but I never put in all that much effort into trying to figure it out. It works great in moderate to larger paper ball shells. 4-6" is the sweet spot for me for KP. You can make it work with 3" shells with a few tricks, and up to 8 or 10" if they're multi-petals or something where there isn't as much burst in there.