mfstraydog1 Posted May 4, 2011 Posted May 4, 2011 well we all know the four is well on its way. i am planning to fabricate some shells again this year. last year i just used cut stars in the shells.It was a great experience but i am looking for more consistency in the stars this year.So with that said i have been looking for info on how to press stars and found a few good tutorials. But they just used a mallet to compress the plates. I would imagen using a press would yuild a better consistency in density and burn time. But i have not been able to find any good info on a starting PSI. i know this will vary from comp to comp and the different burn times i am looking for. Does anyone that presses there stars have any advise on a PSi range for pressing stars with star plates and star pumps. I am planning on using 1/4, 3/8, 1/2 star plates and a 3/4 and 1 1/4" pump.
marks265 Posted May 4, 2011 Posted May 4, 2011 I love my star plates but I still love my roller. They each have their own purpose, but I do find that pumping stars gives me more stars in a shorter time. I have a lot more control in their manufacture because I know exactly how much water or solvent goes into each batch and the density is always the same as long as I charge the plate well. It is possible to pump the stars using very low pressures. For instance, on a 1/2" plate I might put as low as 200 pounds on the composition. This is done while using a pressure to force gauge and depends on the composition I am pressing. Sometimes the stars can be barely handled but dry hard. They are much more fragile then what I would get when rolling stars. You can increase the burn time somewhat by pressing with more force. This is where the dynamics of the user come into play when deciding on a final star use. Some will say to put 1000 psi or more on a composition. Nothing wrong with that either. So there is personal preference that goes with the use of a star plate. To answer your question about a starting pressure. I would start at 500 to 1000 psi on the comp (not the hydraulic pressure gauge). Do make test batches and get comfortable with pumping stars. Consistent charging of the pump or plate will be your biggest battle IMO. Good luckMark
mfstraydog1 Posted May 5, 2011 Author Posted May 5, 2011 sweet thanks for the help. sounds like i might be able to get away with using a arbor press. but this would depend on the presser needed to be applied on the comp and the total surface area of the of the stars.
Peret Posted May 5, 2011 Posted May 5, 2011 I have a 3/8 plate and press with about 100 pounds per square inch of stars, which conveniently enough works out to about my weight divided by the area of stars (in other words, I stand on the plate to press them). They hold together well enough to tumble in prime on ejection, and set rock hard.
guntoteninfadel Posted June 10, 2011 Posted June 10, 2011 Are there any "standards" for stars? I know rockets seem to be based on multiples of ID in regards to optimum length, nozzel size and fuel increments. What about stars? A 1/2" pumped star should be how tall? I think the largest I have pumped is 3/4" or slightly longer. I realize this will result in a longer burning star but what would be considerd normal/standard/best? I am putting these in 2" cans and 4" balls.
Peret Posted June 10, 2011 Posted June 10, 2011 I make two kinds of stars - cut and pumped in a star plate. I tend to make my cut stars thin, so I can use them flat to line a shell case, and pumped stars about as long as they are round, so dimensionally similar to rolled stars. It happens, perhaps by design, that when I fill the star plate to the top they come out about that size. I don't know if there are any "standards", but this is what works for me. Thin glitter cut stars with an inner layer of colored pumped stars is one of my favorite configurations.
guntoteninfadel Posted June 11, 2011 Posted June 11, 2011 . It happens, perhaps by design, that when I fill the star plate to the top they come out about that size. I have a couple of star pumps that when I put in a full charge the resulting star is almost 50% too long, or so it looks, Works great as a comet. I should probably get a volumetric based container to charge the pump with, but that is adding more steps and I am trying to streamline. Got new star plates and have not had a chance to try them yet. They look as if they might be better than the individual pump, we will see.
Mumbles Posted June 11, 2011 Posted June 11, 2011 Most star pumps are not designed to be loaded full and compressed. They usually have a pin, or nub on the rammer that is calibrated to give the correct star height when pressed against the top of the pump. The excess comp is trimmed off, and the comet is ejected. For me it is faster to press the pump into a bucket of granulated composition a few times to load up the tooling.
guntoteninfadel Posted June 11, 2011 Posted June 11, 2011 granulated compositionSo ricing my star comps works kind of like riced bp in a rocket? I was hoping this was the case.
Peret Posted June 11, 2011 Posted June 11, 2011 I have a couple of star pumps that when I put in a full charge the resulting star is almost 50% too long, or so it looks, Works great as a comet. I should probably get a volumetric based container to charge the pump with, but that is adding more steps and I am trying to streamline. Got new star plates and have not had a chance to try them yet. They look as if they might be better than the individual pump, we will see. It takes a bit of practice to load up the star plate for consistent results. Just shaking the damp comp in left my stars a bit short, plus not all the cavities filled properly every time, so now I put a little excess on and tamp it down gently, then scrape the excess off the top, then ram. There's no scientific way to say how much to tamp it down, you just have to do it by trial and error. One at a time pumps, I remember that. Last time I used one, I spent all evening painstakingly pumping single stars, then when I was setting them out to dry I tripped in the darkness and dumped the whole batch into the grass. I found about half of them before the sprinklers came on. With the plate I can make 50 a minute, and though it's still important not to trip when I'm carrying them, it doesn't write off a whole evening's work.
dagabu Posted June 11, 2011 Posted June 11, 2011 Most star pumps are not designed to be loaded full and compressed. They usually have a pin, or nub on the rammer that is calibrated to give the correct star height when pressed against the top of the pump. The excess comp is trimmed off, and the comet is ejected. For me it is faster to press the pump into a bucket of granulated composition a few times to load up the tooling. Ditto for me, the comp stays more consistently moist as well. Pressing comets is a relaxing sort of thing for me, charcoal are my favorite and TT are my daughters favorite charcoal star. -dag
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