mickyp Posted November 20, 2013 Posted November 20, 2013 Thinner pucks break up easier. This is the real reason. There is no performance issues or anything. The first few impacts to coarsely break up the pucks can be less forceful. This does tend to decrease the amount of fine material you get, and goes a little easier on the arm. They dry faster too.Suppose you had a disk the same diameter as your puck with a number of round copper rivet heads set in it, as you applied pressure would it not make the puck fracture in a uniform manner to be further worked on by hand?
Nessalco Posted November 20, 2013 Posted November 20, 2013 I make a bunch of corned powder for cylinder shells, and it really isn't that much extra work. I press 8 fifty-gram pucks at a time in my 2.5" comet pump. There is a fair dwell time required to get the proper density since I'm only using a 12-ton press. While one batch of pucks is in the press, I'm corning the others, while still damp. I screen as I go, and any fines I don't want simply get put back in the mix and pressed again. I can easily puck and corn 3 kilos of BP in a morning. I'll state that when I don't need corned powder, I'll granulate it with a screen - but for some purposes corned powder is a necessity. Kevin
Jonathan Posted November 20, 2013 Posted November 20, 2013 I'm the novice here, but I know this: the ball-milled 75:15:10 I've made and granulated with red gum or dextrin works as well as any B.P. I can imagine. If I'd had this stuff in 1960, I could have flown any of my (aluminum-body) rockets or fired any of my cannons or made any salute I wanted.
Nessalco Posted November 20, 2013 Posted November 20, 2013 Jonathan, Where in New England are you? Have you connected with the New Hampshire Pyrotechnic Association (NHPA)? I agree you can make some fast BP by granulating, very useful for a lot of purposes. However there are some situations where the powder must not break down to smaller particles, and must not migrate from where it's packed. Corned powder meets those requirements. The grains are rock-hard, and the edges tend to interlock with each other so the powder will not move much once it's in place. The fastest powder I make is sumac charcoal + 1% red gum, screen granulated. The most consistent powder I make is black willow ball milled 4 hours, no binder, corned. Different powders, different purposes. Kevin
Jonathan Posted November 27, 2013 Posted November 27, 2013 Kevin, I live in N.W. Connecticut. Haven't connected with any club. Although I like to fly rockets, my main pyro interest is chemistry. Exploring non-mainstream oxidizers and fuels. I've picked up some good ideas here. Although I'd like to see some tutorials or informed threads dealing in-depth with PTFE powder, potassium bromate, the persulfates, lithium salts (nitrate and perchlorate), barium peroxide, and some other chems. Jon
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