Swede Posted April 13, 2010 Posted April 13, 2010 A while back, I picked up nearly 1,000 stainless dowel pins, 1/4" X 3/4". They are perfect for small 1/4" stars. I'm still looking for 3/8", 1/2" pins in stainless. Now, for the plate system itself... I have machine tools and digital readout that will make the drilling of the holes a snap, and they should be accurate. The male plate is going to be drilled blind (not through) and reamed 0.249", with the pins pressed in with a hydraulic press. The female plate will be reamed 0.251", perhaps slightly larger. All of my star production to date has been cut or pumped. I understand the star plate concept, but not completely... basically, the comp is scooped/smushed into the holes, and the male plate is fitted and pressed to create compacted stars. Repeat. Then, the stars are ejected. I guess my question is this - how does one achieve good consistency with the pressing? About how many loadings/pressings need to be done, and is it possible to use deeper female holes and longer pins to do it in one pass? Basically, any new or novel ideas for the "ultimate" star plate would be appreciated.
Mumbles Posted April 13, 2010 Posted April 13, 2010 This thread from a month ago has some info, http://www.amateurpyro.com/forums/topic/4716-star-plate-size-question/ Yes, you can make the female plate deeper, and in fact is what I prefer. You generally use granulated composition to fill the plate, and then compress with one motion to give a final height. You'll have to play a bit with plate thickness and granulation to get the size you want, but it shouldn't be too much trouble. Different compositions will compress different amounts too. Now the not so great news. The female plate is generally 3 to 4x the ID in thickness. Your pins wont be quite long enough. You never know until you play though. You might be able to get away with 2x and a different granulation, or two passes. With granular comp, it's pretty fast to fill. I've never had a problem doing the pressings in just 1 pass. Granular comp actually is pretty consistent. It's rare to get poor results in my experience due to having a female cavity only partially full. (There was no way to make that not sound dirty) The ultimate star plate I feel would be a pill press. You load in granular comp, and it spits out perfect cylinders while you sit back and watch it, perhaps occasionally changing trays.
Swede Posted April 15, 2010 Author Posted April 15, 2010 Thanks, Mumbles - so basically there are really no new ideas on the traditional star plate. What we see in the pictures is pretty much it. I do like the solid appearance of the Wolter plates, and at a minimum, will get some good finger grooves into them. Do plates ever "stick" together? If they do, a series of tapped holes in one plate can be used to separate them with a large cap screw set. I'll try to get something going. I should be able to get at least 0.55" length out of these 1/4" pins.
Swede Posted April 26, 2010 Author Posted April 26, 2010 I've sourced some used 3/8" X 1" SS pins, but only 30 of them - should make an adequate (but small) star plate. For those not on a budget, there is a U.S. supplier called Enco that sells stainless dowel pins about as cheaply as I can find:SS dowel pins
Mumbles Posted April 26, 2010 Posted April 26, 2010 Most dowel pins I've seen have rather radiused or tapered ends. Do you think this or the groove it would leave in the star will effect anything?
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