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perfect model for a hemisphere


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#16 Sprengman

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Posted 03 August 2005 - 10:31 PM

@Karl: The forms are made on a milling mashine. (CNC controlled) The plungers are made on a CNC controlled Lathe. Certainly it is better to make the forms on a Lathe too but in this case it isn?t important.

@LadyKate: The Paperstars are made by my own. I just fold craftpaper a few times to get a "plate" of over 100 Layers. Then I cut the stars on a Bandsaw. The 6" and 8" stars have a better geometrical form. (Like them on the picture above)So the edges square up to each other when I?m glueing them together.


PS: You can see the hole Photo serie at:

http://home.feuerwerk.net/ ---> Gallery ---> Specials ---> Produktion in China

Edited by Sprengman, 03 August 2005 - 10:36 PM.


#17 LadyKate

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Posted 04 August 2005 - 12:31 PM

@LadyKate: The Paperstars are made by my own. I just fold craftpaper a few times to get a "plate" of over 100 Layers. Then I cut the stars on a Bandsaw. The 6" and 8" stars have a better geometrical form. (Like them on the picture above)So the edges square up to each other when I?m glueing them together.
PS: You can see the hole Photo serie at:

http://home.feuerwerk.net/  ---> Gallery ---> Specials ---> Produktion in China

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Well done ... the paper technique was obvious once said - but I had to hear you say it before it was obvious to me. :wub: I may try that out - right now I'm trying to get some comets and comet tooling to work so I'll be fiddling with them a bit.

The picture series was very interesting - I have a 30 minute movie that I taped from TV last month that shows the ordering, construction of mortars in China, and the final display of the Washington DC fireworks show (Pyromania is the name of it - perhaps you've seen it already). They visit the Lido factory in the video. It gave me a whole new perspective on fireworks.

#18 adamw

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Posted 04 August 2005 - 07:34 PM

Wow, pretty snowflakes! :) Nice set-up you got there!
75 : 15: 10... Enough said!

#19 Mumbles

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Posted 05 August 2005 - 01:34 AM

Do you think there are any easier to obtain materials to make the formers from? Not all of us have access to CNC controlled metal forming machines. I have heard some success with lead, and with plaster. I would think plaster would not be the best choice, but it is cheap. If you could perhaps coat the plaster in wax it may be acceptable. I'd be worried about the plaster rewetting. Linseed oil, polystyrene, or even a coat of urethane could waterproof it, and help to prevent sticking. Having access to plastic shell casings woul make forming the molds relativly easy. With the plaster shrinking on drying it would also make room for any of the waterproofers.

#20 Erwin

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Posted 05 August 2005 - 12:19 PM

I'm busy with making 3" paper hemi's now.
Pressing them out of straight kraft paper works but you see folds it it which isn't that nice, making 4 normal cuts in the paper almost to the center didn't work for me.
I still have to try the snowflake forms and papermache.
Newspaper makes nice hemi's to, but it rips apart easely when glued(I use wallpaper glue, which offcourse is water based), but you can't see much folds in them and there cheaper(free) then kraft, but much thinner so it needs more paper.

Here are some pics of my mold:
http://i11.photobuck...shellmould1.jpg
http://i11.photobuck...shellmould2.jpg
http://i11.photobuck...shellmould3.jpg

The screws are for a little standoff when using papermulsh so the shell has the same thickness everywere.
When using pasted paper I get the screws out of it.

Hemi's inside and outside:
http://i11.photobuck...raftshells1.jpg
http://i11.photobuck...raftshells2.jpg

Only need to find a way to get the sides straigt and smooth and find a paper patern to get the fold out of it.

157th edit:
I hope the links finally work now, made the account public.

Sprengman, what's the diameter of those nice papersheets? :)

edit:
I don't press them in a press, I just press the paper in with my bodyweight.

Edited by Erwin, 07 August 2005 - 10:17 PM.


#21 Richard H

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Posted 05 August 2005 - 12:23 PM

No-go. "Please login"

#22 LadyKate

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Posted 05 August 2005 - 01:27 PM

Newspaper makes nice hemi's to, but it rips apart easely when glued(I use wallpaper glue, which offcourse contains water), but you con't see much folds in them and there cheaper(free) then kraft, but much thinner so it needs more paper.

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As Richard H. says, your pictures are behind a password protected system so we can't see them right now.

You are right, newspapers are tender so you have to work quickly or you have Paper Mache. I cut newspaper into strips and run each strip once through the glue bowl and then straight to the form. The nice part about this tenderness is that when you are done, you can cover the ball with a bit more glue and then roll it in the palms of your hands and it all smooshes together and makes a smoother ball. I also add a final layer of thin Kraft when I want it to look good. Did I mention this was messy? I wear latex gloves when I do it.

The shell in the picture below was made with wallpaper glue - I seem to be able to make them smoother with carpenter's glue and they also dry quicker. However, wallpaper glue still works and it is a whole lot cheaper.

Posted Image

As an aside, Shimizu mentions using newspaper as a preferred shell material.

Edited by LadyKate, 05 August 2005 - 01:30 PM.


#23 Yugen-biki

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Posted 05 August 2005 - 04:02 PM

The makeing of a hemisphere doesn't need to be done in a press, though it may yeld better results.

At the bottom of this page http://www.a0tu.com/Yuki/Paper.html you'll find out how I make my hemis.

I use used A4 copy/printer paper with diluted wood glue. The former is made out of cement. About 7 layers is enough to make a sturdy 4" hemi.

Sprengman and Erwin your shell formers are very impressive!

Edited by Yugen-biki, 05 August 2005 - 04:04 PM.


#24 Sprengman

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Posted 06 August 2005 - 04:03 PM

I think that all other methods than making a professionel form, are bricolage.

If you don?t have access to CNC controlled maschines, you can go to a concern that have them. I think for a little money they can build forms for you.

#25 sasman

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Posted 16 August 2005 - 08:17 PM

After looking at those nice molds i have decided to make my own paper hemis..

But before i do can some members tell me if there Home made hemis are as good as the ones you can buy.?.. and can you reproduce them with consistant quality?

I have seen the Vacuum formed hemis on Passfire .They look good Has any member tried this method...

I would prefer the "Power Press" option i have a large Press so i can press the paper with no problems..

Is there any Good information on how Paper hemis are made in china?..

In the above photo you can see Daisy shaped petals of craft , What size Kraft is used ( is it Kraft?).. Then Do you have to glue or paste`each layer?.. Adam mentions that you have to turn each petal so as to cover the Gaps?..

How many layers of paper would you use to make a hemi? Is the hemi made by applying pressure once or do you have to build up the layers with several pressings?
Anyone know how much tonnage would the press need to produce one hemi at a time..

Idealy i would like to see some papers hemis being made,are there any video clips on the internet that shows how it is done? Or any video that i can buy showing how it is done any AFN videos for example?.. 3" 4" 6" 8" are the shells what i would like to reproduce..

#26 Erwin

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Posted 17 August 2005 - 12:26 AM

I think the chinese use thin rice cardboard.

#27 JamesH

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Posted 24 August 2005 - 10:36 PM

Does anyone use a vacu-form technique for producing paper hemispheres. I use the method with excellent results, and its far less work than cutting out pieces of paper and pressing them into a hemispherical mold.
HE WHO HATH ONCE SMELT THE SMOKE IS NE'ER AGAIN FREE

#28 paul

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Posted 25 August 2005 - 11:26 AM

Could you do us a favour and make a few pictures of that process and which materials you use?! As a non-passfire member its sometimes hard to get such pieces of information :D

My flickr photo album


My first very own firework pictures are online!!!

#29 Mumbles

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Posted 27 August 2005 - 07:03 PM

I have used the passfire method a few times. It took a while to get it going, but now I can make usable shells nearly every time. I tried making a 2" shell, and I think this is a little too small for vacuum forming. The walls seem very thick.

I took the passfire design and degraded* it it. I have heard the term "ghetto rigged" for my setup. It was just a simple test to see if it worked, nothing designed for serious use. I cut a hole in the top of a butter container. I cut a ton of 1/16" holes into the plastic hemi and around the hole in the container lid. I hot glued the hemi onto the lid. There was another hole cut into the bottom of the container to accomodate the vacuum source. A thin cotton towel is used as the barrier. Pre wetting the towel really helps get a more even suction.

http://img.photobuck...es/P1010009.jpg
http://img.photobuck...es/P1010017.jpg
http://img.photobuck...es/P1010015.jpg
http://img.photobuck...es/P1010012.jpg
http://img.photobuck...es/P1010011.jpg

[edit] Replaced the asterisked word. It was automatically edited, so I assumed you guys didn't approve.

Edited by Mumbles, 27 August 2005 - 07:11 PM.


#30 LadyKate

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Posted 27 August 2005 - 08:34 PM

I didn't understand the Passfire design all that well - it looked way too complicated to attempt - especially since I was happy with my source for hemis. Kyle's solutions are usually industrial