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Shell wont break hard


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#31 Artopunk14

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Posted 09 November 2006 - 08:26 PM

I use a method of hemi pasting that was detailed on passfire.

You need strips of the following dimension

width= 1/16 of the circumference of the shell
length= 1/3 of the circumference of the shell

The first strip is pasted from one of the poles, across the equator.
The second strip overlaps the first by half and lies 50:50 across the equator
The third strip overlaps the second by half and runs from the other pole across the equator.

You then repeat the process round the shell until it is covered. Each complete turn of pasting round the shell counts as 2 layers as all the strips overlap by 50%

I tried puting kraft paper over my shells before but it was very aggravating, the kraft paper wouldnt conform to the shell and the kraft wouldnt stick. What glue do you use? Do you wet it first?

#32 Pretty green flames

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Posted 10 November 2006 - 05:40 AM

I tried puting kraft paper over my shells before but it was very aggravating, the kraft paper wouldnt conform to the shell and the kraft wouldnt stick. What glue do you use? Do you wet it first?


You soak the strips in wheat paste and then paste them on the shell.

#33 RegimentalPyro

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Posted 10 November 2006 - 08:50 AM

I tried puting kraft paper over my shells before but it was very aggravating, the kraft paper wouldnt conform to the shell and the kraft wouldnt stick. What glue do you use? Do you wet it first?


I actually cheat a bit here. You can buy rolls of Kraft that are pre-gummed. The rolls I use are 2 inches wide and look to be about 250m long.

#34 Artopunk14

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Posted 10 November 2006 - 11:51 AM

I actually cheat a bit here. You can buy rolls of Kraft that are pre-gummed. The rolls I use are 2 inches wide and look to be about 250m long.

Ill have to pick some up,
Thanks

#35 Mumbles

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Posted 11 November 2006 - 05:52 AM

Unless you cut the rolls, you must make monster shells, like 10"+. I also use gummed tape, so much faster. I however use 1" wide stuff. Works well for 4" - 6". The 3" has a hard time to conform. I am interested if you do infact cut the rolls, and how you do it. I would like some 3/4" wide for my 3". So if you can easily cut them with a bandsaw or something, I would pick up some 1 1/2" wide rolls.

#36 adamw

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Posted 11 November 2006 - 01:42 PM

Incase you are looking for gummed tape, the stuff from Staples is perfect for pasting shells. For 3" and below, it needs to be cut in half so it conforms properly. Combine it with 'Lap' wallpaper adhesive (proper starch based) available from Wilkinsons, Focus etc and you never have a problem with poor breaks.
75 : 15: 10... Enough said!

#37 GBthriller

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Posted 12 November 2006 - 05:56 PM

Incase you are looking for gummed tape, the stuff from Staples is perfect for pasting shells. For 3" and below, it needs to be cut in half so it conforms properly. Combine it with 'Lap' wallpaper adhesive (proper starch based) available from Wilkinsons, Focus etc and you never have a problem with poor breaks.

I just fired a 3" last night. It was pretty good. Sorry no vid to show.
The 3/8 pumped D1 stars were not a strict uniform size. The point of building this shell was to try and improve my skill and get a bigger, harder break. It was a success, but later my wife said "I get the feeling your unhappy". Isnt that a kicker? Of course I'm unhappy with it, I'm a pyro.

I used thin hemi's made with newsprint and pva. filled each side with stars, lined with tissue paper, filled with KP on hulls, (it's my first KP shell) I added 5g of FFFFg. I then pasted with more newsprint and pva about three layers, let it dry for three days. Next layer was cotton string, many random wraps coated with waterproof wood glue, that dried very hard. Left roughly 3/8 gaps in the string layer criss-crosses. Next layer was another three of newsprint and the same waterproof woodglue. Resulting in a very hard experior after about a week of drying.

If Adams meathod works better, I never invest that much time in building again. I'll start one of Adams type tonight and test in a week.

My feeling is that the shell report should be at least as loud as the morter. (You shouldnt be on top of the morter). Is that about right?

GB

#38 Artopunk14

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Posted 18 November 2006 - 08:56 PM

I just tried a 4" shell out with pasted kraft paper over the plastic, best one so far. I'm coming to the conclusion that I'm just going to have to use all kraft and plastic is just not for me.

Thanks guys

#39 Mumbles

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Posted 21 November 2006 - 09:26 PM

I've always gotten my best results from paper. I picked up some very nice hemis at the PGI convention this ear. I am assuming you're in europe somewhere, so I am not sure where to advise you getting them there. Cannonfuse and pyrocreations definatly ship overseas though.

I have gotten some good breaks from plastic though. Just not as uniform as paper. A layer of masking tape over the plastic allows for kraft to adhere better to the shell, which gives a better break. Pasting of plastic does help some. I think one just needs harder breaks with plastic to get the uniformity of paper. KP or H3 may work. BP on rice hulls with a whistle or flash bag in the center is also something to consider.




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