Mumbles Posted June 30, 2009 Posted June 30, 2009 I don't know how well that would work. The wetness needed to really extrude some compositions could potentially cause reactions, as well as making the stars kind of sloppy wet, causing them to lose their cylindrical shape.
Swede Posted June 30, 2009 Author Posted June 30, 2009 It's just a daydream. It would require hydraulics or an ACME threadform + piston, and a vessel with the strength to withstand the pressure, say DOM stainless tube, 1/2" wall. With enough pressure, you can extrude just about anything, taking into account the effects of pressure on the comp. Heck, pasta dough is reasonably stiff, and easily extruded on a simple machine. It would be a challenge, I think, but not impossible. The fact that most stars are larger than 1/4" helps.
Bonny Posted June 30, 2009 Posted June 30, 2009 It's just a daydream. It would require hydraulics or an ACME threadform + piston, and a vessel with the strength to withstand the pressure, say DOM stainless tube, 1/2" wall. With enough pressure, you can extrude just about anything, taking into account the effects of pressure on the comp. Heck, pasta dough is reasonably stiff, and easily extruded on a simple machine. It would be a challenge, I think, but not impossible. The fact that most stars are larger than 1/4" helps. It would be a challenge for sure. Due to the comp also being dampened before entering the machine (unless that was to also be automated) you would likely need a screw feed (auger) to feed the extruder, if it was to be screw extruded rather than pushed by hydraulics. I work in extrusion and would have a few ideas if you ever want to try something like this.
wymanthescienceman Posted July 1, 2009 Posted July 1, 2009 (edited) I've made small stars in the past by using 1/8" acrylic sheet and drilling 1/8" holes in it to effectively make a star plate. I never finished it because I only had a low quality drill press at the time which wasn't square, so the holes would never come out right. Because of this, I used the drill bit to push the stars out instead of making the pin plate, and it worked quite well. My idea at the time was to use the little stars not only as-is for effects, but also for to make inert/effect cores for rolling larger round stars. I am in the process of acquiring a new drill press so I can finish the start plate, although this time I'm going to be using 1/8" aluminum plate and some nice 1/8" SS dowel pins for the pin plate. I used a silver shower/streamer composition and made some little mines with them and also for effect in 1/4" ID bottle rockets. They did burn relatively fast but I bet if you tweak your composition a bit you could get them to work properly for your particular application. I like making small compact fireworks because I live in town, and just because they seem more of a challenge to me to get a good effect from. Those 1" can shells are perfect for what I like to do so I'm going to order some of those cup sets soon. As for the extruding idea, I thought about it before and have tried to do it using a syringe with a fat tip, but every time I tried it, the composition would stick in the tube and all of the liquid would squeeze out. It was probably the composition I was trying, but IMO you would need a truly 'doughy' composition for that to work, so a lot of comps won't work with that method. But experimentation is the only way to find out! Edited July 1, 2009 by wymanthescienceman
d4j0n Posted July 2, 2009 Posted July 2, 2009 (edited) 1/8 seems overkill unless they're really slow. I believe my stars were all just under 1/4". Takes a bit of experimentation to get them the size you want, note that the layer of prime actually makes a difference here since this is such small scale. Cutting stars seems easiest here since there's no point in stressing uniformity to that degree in this small scale. The ease of that cut star corner ignition also helps. Primed bits of wrapped fish/crackle work great too as stars. This is what I ended up with in terms of star size, you can take it or leave it:Star sizes should be cut wide enough such that about 5 will fit around the burst tube.The thickness of them plus prime should make a perfect fit in the cavity. As for the shells not fitting in the tube, I'm not entirely sure, but I believe that commercial spiral wound cardboard tubing has a larger ID than other tubes rated at the same ID. If you are having fit issues, I advise you to clip lengths of whatever mortar you're using, shim them with some layers of masking tape parallel to the length, and use those as a press to seal the shell halves together. After the shell dries, it should shrink by the nature of paper the wood glue. I think this is what I always do but I kind of left it out of the tutorial Here's a video: 1in_chrysanthemum__8___Akwapo.mpg Edited July 2, 2009 by d4j0n
Swede Posted July 2, 2009 Author Posted July 2, 2009 (edited) TY for the tips. My daughter and I finished 35 of these yesterday, a mix of small stars of different types. Stupidly, I forgot that I have a huge collection of flying fish and falling leaves fuse that would have been ideal for these little guys. I need to crank out a few more. Especially for tiny colored stars, falling leaves would be nice, rather than trying to mix up little stars from scratch. Priming would probably be needed, but their shape would allow for a good density inside the shell. I did try a few with a more vigorous burst - some KP and whistle - in case the BP isn't adequate. Just an experiment. Two other things we did slightly different - since the lengths of the rolled kraft burst tubes varied slightly, some were a bit too long, others too short, so to keep the burst isolated and gently compacted, we rolled a little ball of tissue and jammed it into the tube on top of the burst. The last difference was in gluing the outer cup to the filled inner... we found that jamming them together dry, it expanded the outer cup slightly, creating a decent gap. Using a small paintbrush, we thoroughly dabbed glue into the gap, then used a cable tie to close it. Excess glue squeegee'd out, and the strength was excellent. These have been fun so far, and perfect to introduce a kid to making simple shells. We talked about timing, burst, priming, etc. They'd also serve well as timed inserts to a larger shell. Can't wait to launch them. I plan on daisy-chaining a few tubes together to give a timed "barrage". Edited July 2, 2009 by Swede
dagabu Posted July 21, 2009 Posted July 21, 2009 TY for the tips. My daughter and I finished 35 of these yesterday, a mix of small stars of different types. Stupidly, I forgot that I have a huge collection of flying fish and falling leaves fuse that would have been ideal for these little guys. I need to crank out a few more. Especially for tiny colored stars, falling leaves would be nice, rather than trying to mix up little stars from scratch. Priming would probably be needed, but their shape would allow for a good density inside the shell. I did try a few with a more vigorous burst - some KP and whistle - in case the BP isn't adequate. Just an experiment. Two other things we did slightly different - since the lengths of the rolled kraft burst tubes varied slightly, some were a bit too long, others too short, so to keep the burst isolated and gently compacted, we rolled a little ball of tissue and jammed it into the tube on top of the burst. The last difference was in gluing the outer cup to the filled inner... we found that jamming them together dry, it expanded the outer cup slightly, creating a decent gap. Using a small paintbrush, we thoroughly dabbed glue into the gap, then used a cable tie to close it. Excess glue squeegee'd out, and the strength was excellent. These have been fun so far, and perfect to introduce a kid to making simple shells. We talked about timing, burst, priming, etc. They'd also serve well as timed inserts to a larger shell. Can't wait to launch them. I plan on daisy-chaining a few tubes together to give a timed "barrage". I dug through my stuff and found a bag of 1" plugs that look just like these. I had the same problem with gluing them and am way too cheap to use zip ties so I just (following your idea) brushed them with glue and stuffed them into a 1" PVC pipe that had a piece of copy paper lining the inside. I got 10 in the tube and let them dry. I pushed the tube out and pealed the paper off and have perfect 15/16" inserts! Now, where to fire them that wont tick off the Nazi neighbors?
psyco_1322 Posted August 3, 2009 Posted August 3, 2009 Swede, Did you shoot your mini's on the 4th? How'd they come out?
Swede Posted August 4, 2009 Author Posted August 4, 2009 Swede, Did you shoot your mini's on the 4th? How'd they come out? Surprisingly well. We made a wide variety of the little shells, some with differing burst comps, differing stars, a couple of salutes. The best burst was those that made use of whistle + BP. BP alone gave good ignition but was too weak, while Whistle or FP alone tended to shatter or blow blind the weaker stars. Two or three launches did not ignite the visco time fuse due to poor priming, but the majority worked fine. I think one of the problems with these tiny shells is getting enough stars in there in the first place to get a decent visual effect. I have no idea why I did not make use of flying fish or falling leaves, which could be set to encircle the inner burst tube, and you'd get a good density of colorful and varied effects, especially mixing cracklers with color. You could also increase the burst a bit without fear of shattering the fuses, giving a better and wider spread. Overall, they were fun, and my daughter took great pride in her work. The report from the mortar tube was very subdued. I think it'd be possible to design a very stealthy shell by using only flying fish. Prime one end well, give the shell just enough burst to break and ignite the FF, and let the FF do their thing.
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