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Paper Hemis

hashashan

By hashashan
in Member Tutorials

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hashashan Newbie

hashashan

Posted
Posted

Well the idea is not mine, i give the credit to KarlosH from the UK pyrotechnics forum, however the tutorial is mine for you to use :)

 

You'll need the following:

http://www.apcforum.net/files/hemi0.JPG

1) Circles cut to a special form(details below), made from any sort of rough paper

2) A mold(no details unless asked)

3) Glue, I prefer dextrin, it just gives the best results. The dextrin should be mixed with water to a thick slurry.

4) Thats the slurry :)

 

http://www.apcforum.net/files/hemi2.JPG

 

the radius of the circle should be Pi*radius of the shell. I usually add about 2cm just to make it more convenient.

Draw a small circle inside the big one, also divide the circle into 6 even parts. Don't do more then 6, it just makes the hemis worse.

Cut along the lines up to the small circle.

 

http://www.apcforum.net/files/hemi3.JPG

 

Smear some glue on TOP of the first circle and put it in the mold in such a way that each eave overlaps the following.

 

Now comes the dirty part:

 

http://www.apcforum.net/files/hemi9.JPG

Use your finger to flatten the circle to the mold, make it as good as you can.

 

Repeat the last steps so that you put as many circles as you like, I use 6 for 4" hemi.

 

NOTE : you smear glue on top of the first circle and on the bottom of all the rest.

 

http://www.apcforum.net/files/hemi8.JPG

 

When you complete all the stages, flatten everything as tightly as you can and pull it out carefully.

 

Dry it slowly not in direct sun so that it will remain straight. If you make many of those put them one on top of the other in a tower-like form.

http://www.apcforum.net/files/hemi6.JPG

 

After the hemi had dried completely cut the edges and voila you have your perfectly round hemis.

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justanotherpyro Newbie

justanotherpyro

Posted
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Another material that I am having success with is the cardboard from cereal boxes, beer/soda boxes etc...soaked in liquid starch/water roughly 50:50 and cut to a similar shape. It cuts down on how many layers you need, and the rigidity of the cardboard makes it hold the spherical shape pretty well. Coat the inside of the mold with Al foil to keep it from sticking. Nice tutorial btw.
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Xtreme Pyro Newbie

Xtreme Pyro

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Very nice tutorial i have been looking for a good tutorial on making paper hemi's to save me a bit of money, and just out of curiosity what did you use for the mold for the hemi's?
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hashashan Newbie

hashashan

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The mold was made by me.

I just took a Styrofoam ball of the wanted size and made an epoxy mold from it, then I poured acetone all over it in order to remove the ball.

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Karlos Newbie

Karlos

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Hallo Hashashan. I see two problems. Youre dextrin glue contain much of water, and paper is wet. Glue solution saturate to paper, and his adhesiveness is small. If is paper wet, hemispheres are deformed after drying.

You are forming paper in to mold only with fingers, but for this operation is necessary any plastic former, like smooth cylinder. Paper must be perfectly contiquous on mold. Perfect conglutination of paper layers!

Bye.

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hashashan Newbie

hashashan

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Maybe the camera shows it like that.

The hems were not too wet, and doing it with the fingers in my opinion is better, you can feel bubbles.

Anyway After some practice the hemis stopped deforming and now are perfect.

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Karlos Newbie

Karlos

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For pasting is needed viscid glue, wchich don´t saturate to paper and paper is still like dry(only lightly wet). Maybe for pasting is better dark dextrin, which is quite solvent.

 

good luck

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gods knight Newbie

gods knight

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Could nail glue be used? i saw a pint of it at store for 4$ I onced used it to roll tubes because of its ability to dry extremely fast and the tubes turned out rock hard. would the same be said for hemis?

 

The idea is to get a rock hard hemi within ten minutes.

 

 

 

 

 

(I know its more expensive than the other glues)

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Mumbles Explorer

Mumbles

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You know, patience is a virtue in pyrotechnics. Why do you need them so fast? Is it really that hard to make 10 or 20, and let them dry over night?
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gods knight Newbie

gods knight

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I suppose not, I just wondered if it would work, ill stay with the dextrin method then
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Mumbles Explorer

Mumbles

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Anything that sets that fast is probably some sort of epoxy or something to that effect. It's shattering effect upon breaking kind of takes away from the eco-friendly side of things for paper, and again poses a hazard for sharp fall out.
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TheSidewinder Enthusiast

TheSidewinder

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That's interesting.

 

Looks like Hebrew (which I had no idea was even installed). Wonder what other esoteric languages we have floating about.

 

EDIT: LMAO... Mumbles, do an Edit on that post. ;)

 

And for others, yes, it's Hebrew. In edit mode, it's right-to-left formatting. For a moment I thought the editor was screwed up, but no, it's just properly following that language's syntax.

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  • 3 years later...
TheEvilGod Newbie

TheEvilGod

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This is a very good tutorial. Will have to try this out as soon as possible. About how long does each hemisphere take to make? Would like to see the pictures re-uploaded :-).
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petroleum Newbie

petroleum

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Would like to see the pictures re-uploaded :-).

 

It will be wonderfull =)

 

 

 

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Mumbles Explorer

Mumbles

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Don't hold your breath. The poster hasn't logged in in 2 1/2 years. There may be other similar tutorials around though.
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petroleum Newbie

petroleum

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Don't hold your breath. The poster hasn't logged in in 2 1/2 years. There may be other similar tutorials around though.

 

 

It was interesting for me to see photoes. I have my own tutorial with photoes and parameters, but it is not in english. Unfortunately I dont have enought time to translate and share it.

 

 

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Mumbles Explorer

Mumbles

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I think the description is pretty good. Understandably not everyone natively speaks English though. Having done something like this to make liners for multi-petal shells, I can say that it is a pretty quick process. If you have a bunch of shapes cut out, it only takes a minute or two to slather on some glue, and conform it to the mold. I found it easier to make them with a male mold if you intend to use your hands.

 

The above tutorial, it sort of like this one by BJV, but in reverse using a female mold instead of a male one.

 

http://www.amateurpyro.com/forums/topic/5505-newspaper-hemispheres/

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  • 2 weeks later...
orangie Newbie

orangie

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i was on the site yesterday and searched my history......i found a website from the UK i belive he was a supplier and he runs on this form....he had all types of paper and tubes and what i liked the most was he had girindola wheels for purchase......

 

anyone know who he is

 

i cant start a thread so i try here

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