MadMat Posted August 8, 2015 Posted August 8, 2015 I'm fairly new to R candy (made about half dozen rockets, no cato's) and I've always cooked and hot cast my rockets. Recently, on skylighter's site I saw that they were cold pressing their rockets. Granted they were using sorbitol and I have been using sucrose (standard formula with iron oxide). Is cold pressing sucrose feasible? I have been having problems, especially with smaller rockets of getting them packed fully before the @#%$@ cools and hardens. I have been giving it some thought to try cold pressing, but, milling and mixing becomes more important. I've tried milling sugar and came up with a sticky, clumpy mess. Also, I know its supposedly safe to drill the core out, but the idea of drilling into rocket grain just goes against my better sense of safety. Any ideas or suggestions on the matter?
Oinikis Posted August 9, 2015 Posted August 9, 2015 What do you mean by cold pressing? Just mill/mix the ingredients and press? That's just a basic rammed rocket. My personal preference is hot casted Rcandy. Why? Because that way the ingredients mix way better than you could achieve with milling, without requiring the hassle. Then, since it's casted and it hardens, it bocomes a solid lump, much less prone to fracture, and also more consistent and dense, plus you can make various shapes with it. Probably the biggest disadvantage of rcandy is that it needs to be hot when casted, so casting process has to be well planned, however I do not struggle with casting, because I have found a technique which works best for me (Also I have thick skin, so handling it work me isn't really a problem). Another problem is it's hydroscopic, but after the grain cools I just insert e-match, and seal it with tape, and that way it stays nice and dry.
stix Posted August 10, 2015 Posted August 10, 2015 (edited) Cold pressing is definitely feasible and when done properly can be (almost?) as good as melted. You need to mill your ingredients very intimately and then press using a decent shop press or similar. Small increments over time is best. Ramming with a mallet is similar, but nowhere near good enough. I know someone who has an industrial sized screw press (well, pretty big) and their only method has been cold pressing - it works just as well as my melted version (to date) but is very time consuming imo. Don't bother with milling sugar - buy "icing" or "confectioners" sugar - it's already a fine dust like powder. Mill up your kno3, then mix both together preferably with a ball mill. There are various ways of making sugar rockets. There are also many discussions on this forum regarding those different methods: http://www.amateurpyro.com/forums/topic/10413-best-place-to-buy-sticks/Although the topic seems unrelated, Post #18 sets out the most common methods, but read it from the beginning, it's a worthwhile read Cheers. [edit] btw. the motors that I'm talking about are not drilled out. They are made using tooling with a central mandrel/rod. The mandrel is extracted after pressing (dry or melted) leaving an almost perfectly round outer and central core. Edited August 10, 2015 by stix
schroedinger Posted August 10, 2015 Posted August 10, 2015 (edited) For these small engines i normally hot press them, pour in the r-candy, then stuff it down with a rod fitting between the spindle and tube (one or two times around) then press all down with a normal rammer. Hand pressure is all you need, apply force for about 30 seconds. This way you end up with a nice grain. The first stuffing is not needed but helps with keeping fuel out of the rammer bore.About 4 pressings is enough for a 1 lb engine. Edited August 10, 2015 by schroedinger
MadMat Posted August 11, 2015 Author Posted August 11, 2015 (edited) Thanks for the info and opinions. I have homemade tooling for pressing both 1/2" and 7/8" id rockets. What I usually do is make the nozzle. Drill it out with a fixture I made to ensure its on center. Then I put the rocket body on a stand with a steel core pin. My rams are wooden with centered holes that clear the core pins. Yeah, I know I have to clean out the holes on these when I'm done, but its not that big of a deal. I usually mix my comp with water and cook it off. Edited August 11, 2015 by MadMat
dagabu Posted August 24, 2015 Posted August 24, 2015 I'm fairly new to R candy (made about half dozen rockets, no cato's) and I've always cooked and hot cast my rockets. Recently, on skylighter's site I saw that they were cold pressing their rockets. Granted they were using sorbitol and I have been using sucrose (standard formula with iron oxide). Is cold pressing sucrose feasible? I have been having problems, especially with smaller rockets of getting them packed fully before the @#%$@ cools and hardens. I have been giving it some thought to try cold pressing, but, milling and mixing becomes more important. I've tried milling sugar and came up with a sticky, clumpy mess. Also, I know its supposedly safe to drill the core out, but the idea of drilling into rocket grain just goes against my better sense of safety. Any ideas or suggestions on the matter? There are also non-traditional methods of making sugar rockets, make up your R-candy as usual but use a cheese grater to make a granular mix. Use that mix to press a rocket just like you would make a BP motor.
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