6 replies to this topic

[butch24]

Do you have to paste plastic shells. I have seen were they just wrap tape around the shell is this all you have to do?

[dan100]

plastic shells should be bound with a suitable solvent before any taping or pasting. it depends what you want to achieve and what size/form they are, its hard to get a good even break from small plastic shells
ive seen gamon canisters that arent pasted and balls taped with fiberglass strapping tape, but i would paste and dial it in from there.

dan.

Edited by dan100, 14 August 2011 - 08:11 AM.

[Mortartube]

No, they don't need taping. The best way to join them is to almost fully push the hemispheres together and drip a toulene based adhesive into the groove between the hemispheres using a metal rod You only neeed about 2 or 3 drops). The shell should be on it's side so the groove runs vertically and gravity will take the glue all the way around the groove. The clear liquid cement used for model plastic kits has a small amount of toluene in it. As soon as the glue has tracked all the way around the groove push the hemispheres together as it is very quick drying. This method melts the plstic and effectively plastic welds the the halves together. You will not be able to get it apart again, so make sure everything is correct before you do this.

[Arthur Brown]

The taping serves several functions, you have to chose your priorities.
Taping makes the diameter bigger so makes the shell a tighter fit in the tube, and sometimes goes higher.
Taping holds the hemis together as the burst builds so sometimes you get a bigger burst radius.
The burst compound in plastic shells is usually different from the burst for a paper shell, it's unlikely that a beginner will optimise both without considerable experimentation.

Some places don't like plastic hemis because of the environmental aspect of the discarded plastic shrapnel including sharp pieces. Paper is cheaper and it disappears into the soil very quickly.

[butch24]

Thanks to all for the info. As you can tell i am a little new to shell building and have another question. I was wondering do you stack cut stars just like you would round stars up the wall of the shell.

[T-sec]

The true and good way to paste shell parts together, is to solve some plastic shell parts in 1/2 liter of Thinner solvent used for painting, etc.
Add 1/2 liter Thinner in a glass jar with lid, and add like one broken plastic shell part in to it. Let is slove for 24 hours with closed lid.
If you do this right, you will get a half thin/thick substance, and this is the perfect fast glue to paste your identical shells with like a weld.

[Mumbles]

Yes, you can stack cut stars along the inside of the round shell wall just as you would with round stars. In bigger shells I can tell you that the aerodynamics of the star shape tend to make the breaks look a bit less visually pleasing.