Die cutting paper patches/skins for small shells

[hcb]

I started about 6 weeks/2 months ago to make BP and try to make BP model rocket motors. That has morphed into some fireworks. I'm new. I don't know much. This may not be new but maybe helpful, hopefully, so I'll post it.

 

I really want to make some shells. I've been making stars and shooting them in a home made star gun. That's fun... but I want to do a mortar and shell setup. I'm cheap (sort of) and impatient (very) so buying pre-made pieces from a pyro source won't get it. While walking through housewares at Wal-mart (all great stories start that way) yesterday, looking for pyro tools, I saw a lemon and a lime squeezer. Bingo! That's what I need to make small shell casings! I cut some circles out of some paperboard roll paint mask heavy whatever paper I got at Lowe's and scored them (cut them radiating from the center to the perimeter partway) to let them fold up into the lime mold and...glue, press, repeat. It works well, but cutting those discs *sucks*.

 

I had an idea: make a die cutter. I had a piece of heavy-wall pipe plug left on the shop floor from my home made cannon and spun it up on the lathe and cut it out to the right ID, put an edge on it, and used the shop press to smash it into a piece of cutting board left over from the work bed I built for my 1-ton (pads between the bed and frame). It works pretty well. It cuts great but the thing finds a soft spot and cuts there, first, then kind of leans. I have to move the assembly a bit off center and press again to get them all cut without burying the cutter into the cutting board. But I got 8 perfect circles at a time this way. the picture with about 40 of those discs took less than 5 minutes and that included getting another piece of folded up paper ready to cut.

 

If one didn't have a lathe, a Dremel and a lot of time could get one there. Or pay a shop to turn the piece for you. The cutting board was some HDPE (which was kind of special about it (not just nylon or something...I forget now, it's been a year and a half...which is why I used it for the pads under the truck bed) from Amazon, nothing fancy.

 

I scored one of the circles and it's a great fit. It could be larger in diameter to stick up above the equator but I'll be taping/wrapping the shells when completed so I'm not sweating that. The lime squeezer makes it quick and easy to form nice hemispheres.

 

Anyway, posted with the hope it helps someone.

 

--HC

[BetICouldMake1]

Nice work HC. Since I'm a die hard cylinder guy I can't help but throw it out there that you could just use a setup like that to cut end disks and build yourself some small cylinder shells. No hemispheres needed. Who knows, once you build a few you might find you wanna stack a bunch of them together like this

[snapper]

you will find the effort vs the price to just buy hemi sets especially in sizes under 4 inches is silly. the time you will spend trying to get the hemis pressed after using your paper, glue and making cutting dyes then making pressing dyes is silly. LIke stated above make cylinders if you want to build every single component yourself or just order hemis as they are very inexpensive and consistent in manufacture. I ventured down this same path and decided my time doing other things is more valuable than pressing hemi halfs. your going to be spending plenty of time making everything else that go's into these shells plus pasting amd making match/leaders etc.

[Arthur]

I've certainly never felt the need to make hemis, lots of time and tooling for something that can be bought more cheaply.

 

Either start making cylinder shells, and multibreaks, or use commercial hemis

[SeaMonkey]

For the Amateur Pyrotechnician who tinkers at the art it

may be more challenging and fun to make the whole

thing 100% with what is readily available and at hand.

 

For mass production at the professional level things

surely would require a more focused emphasis on

time and money.

 

I'm in the former crowd. Finding a way to get it done

by reliance on wit and innovation is the much more

practical way to make colored fire and smoke and noise.

 

Always safely of course.

[hcb]

Nice work HC. Since I'm a die hard cylinder guy I can't help but throw it out there that you could just use a setup like that to cut end disks and build yourself some small cylinder shells. No hemispheres needed. Who knows, once you build a few you might find you wanna stack a bunch of them together like this

Thank you. That's a nice effect you got out of that shell. I like that. I'm still, slowly, working on making my first shell. I'm doing rockets, too, and learning to roll stars and too many things. All slowly. But I've not blown myself up yet, so there's that. I will make a cylinder sometime, just not sure when. They do look a bit easier to construct entirely from nothing factory-made, though. Maybe I should try that first.

 

I've since bought some shell pieces, but this is still kind of a neat idea. Plus, I don't see why this idea can't be used to make wraps for shells.

 

--HC

[hcb]

you will find the effort vs the price to just buy hemi sets especially in sizes under 4 inches is silly. the time you will spend trying to get the hemis pressed after using your paper, glue and making cutting dyes then making pressing dyes is silly. LIke stated above make cylinders if you want to build every single component yourself or just order hemis as they are very inexpensive and consistent in manufacture. I ventured down this same path and decided my time doing other things is more valuable than pressing hemi halfs. your going to be spending plenty of time making everything else that go's into these shells plus pasting amd making match/leaders etc.

I very much agree. This isn't the way to go if you want to just make shells. But it's handy if 1) you don't have any shells and 2) don't want to wait for an order. Or if you just like making things the hard way. Subsequently, I placed an order for some stuff and added some hemis to the order. I have factory-made stuff now. But I suppose these could still be petaled and used to wrap/tape some of the factory shell casings.

 

--HC

 

--HC

[hcb]

For the Amateur Pyrotechnician who tinkers at the art it

may be more challenging and fun to make the whole

thing 100% with what is readily available and at hand.

 

For mass production at the professional level things

surely would require a more focused emphasis on

time and money.

 

I'm in the former crowd. Finding a way to get it done

by reliance on wit and innovation is the much more

practical way to make colored fire and smoke and noise.

 

Always safely of course.

I do a lot of things once. This is probably something I'll do once. But I'll always know how to do it. Might never need it, but it was still fun to try it. And these forums aren't about telling everyone what will work for them, they're about sharing information. Maybe this will help someone else. There will be others who, like you, enjoy doing it all from scratch (at least sometimes). There aren't any right answers in this particular endeavor which fit all people.

 

--HC

[memo]

beticouldmake1

 

really nice work, try a 3 inch next ,then a 5 ,then a 6 ,then a 8 . i can hardly wait..... i have made it to a 8 - 3 break. still thinking on bigger shells or maybe just more breaks.

[BetICouldMake1]

beticouldmake1

 

really nice work, try a 3 inch next ,then a 5 ,then a 6 ,then a 8 . i can hardly wait..... i have made it to a 8 - 3 break. still thinking on bigger shells or maybe just more breaks.

 

Thanks memo. Funny you should mention...

 

Breaks could have used a little boost but still happy with it for the most part.

 

Currently working on this guy

 

 

Edited April 27, 2020 by BetICouldMake1