tentacles Posted April 7, 2008 Posted April 7, 2008 Actually, forget the shop press and arbor press i talked about, I'm buying this : http://powerplustools.dk/images/PPT0302_DK-t.jpg 20 ton press, 3,445DKK (713$) for the press and 524DKK (108$) for shipping. This one would be a killer to have in the shop, let's see what the parents say pudi: That looks like cplmac's press. They sell one just like that up here, for like $350 at princess auto. They're Chinese made, and reasonable quality for that. cplmac could tell you a lot more, I'm sure it could use some reinforcing if you're going to do big stuff like 3" rockets. Possibly even for 4lb rockets.
Mumbles Posted April 7, 2008 Posted April 7, 2008 He posted about it over on passfire the other day. He said the press works great as is for everything up to 6lb. For the 60lb (3" ID) rockets he said it needed reinforcement. Imagine that. It should be fine as is probably for anything you'd be throwing at it.
FrankRizzo Posted April 8, 2008 Posted April 8, 2008 I seem to recall him posting that he'd bent the bottom support pressing one of those monster-bore, space shuttle boosters he builds. Bowing 2 pieces of steel channel is craziness.
lnstantkarma Posted April 16, 2008 Posted April 16, 2008 I finally finished my press, I've got the features I wanted like the gauge and the return springs. I've tested it for up to about 2000 psi which is about 6500 loading pressure and that's good enough for my 1lb rockets so far. hydraulic press
FrankRizzo Posted April 16, 2008 Posted April 16, 2008 Make sure to attach a blast shield to your press (polycarbonate, plywood, steel, etc.). That design relies on the support of the shield to keep the threaded rod from bending toward or way from you under pressure if your tooling isn't absolutely centered. The rod has great tensile strength but it bends easily. Also, that steel bar stock and channel bend quite readily under the extreme force that your press will generate. I'll post some pics later of the bent channel and bar stock from the press I made using a similar design.
lnstantkarma Posted April 16, 2008 Posted April 16, 2008 Thats a good idea, I always have to make sure my tooling is centered for every increment. I was going to get a shield when I started making whistle rockets but I might move that up on the list now. And I am worried about the channel and bar stock bending, I won't go higher than 2000psi but I would like to and I don't know if more metal would really let me handle much more pressure.
Mumbles Posted April 17, 2008 Posted April 17, 2008 Even BP rockets are going to require about 3x that value InstantKarma, or were you talking 2000psi jack pressure. . 6600psi I believe is about standard. I think you may be more interested in total force though. There is obviously a difference between 8000psi on 1/2" rocket tooling, and 8000 PSI on 3" ID rockets.
jacob Posted April 17, 2008 Posted April 17, 2008 How many tons is your jack rated at lnstantkarma? I've maxed out a 6 ton jack on what looks like the same Steel channel and no end plates without it bending at all. And Frank is right that design will bow alot and kick out your tooling without reinforcement.
lnstantkarma Posted April 18, 2008 Posted April 18, 2008 Mumbles I'm talking about the jack pressure 2000 psi, for 5500 on my tooling or 2340 for 6500 anyway I use the calculator on passfire so I should be good. and jacob, I have 4in channel and 1/2in flat bar with an eight ton jack, i know the jack is overkill but it was only a dollar more and when you say reinforcement do you mean the lexan? what thickness do you have? I'm looking at 1/2in thick off of ebay unless you have any suggestions
jacob Posted April 24, 2008 Posted April 24, 2008 I used 3'' channel and no end plates or blast shield, however I only did 1lb BP rockets with it. Yes by reinforcement I mean a shield, and maybe cross straps on the back, not sure on the straps though because if you had a rocket pop on the press they might prevent pieces of it going out the back, I don't really think it would be a safety issue but I've never tried it. 1/2'' sheet should work, but remember the thicker the better, it may have been posted before, but Tom Calderwood documented an interesting blast shield experiment done at the 1999 "do it by the river" (I think)It can be found here I thought maybe if you put two pieces of Polycarbonate at a right angle pointed toward the rocket, it would dissipate the energy better if one were to go off, you would need to make them plenty long so not to get burned by the flames and gas comeing off the sides, but I think it would work.If you're going to use plastic, make absolutely sure it's Polycarbonate, not Acrylic.
jacob Posted June 15, 2008 Posted June 15, 2008 Here's a pic of my new press, it's a full hydraulic setup with two-way cylinder, 3.25'' ID by 36'' long, I haven't cleaned it up yet or painted it but it seems to function good, although I haven't tried to press any rockets.All I have left to do is make a blast shield and proper fluid reservoir (I'm currently useing an old water jug ) Questions? comments?
tentacles Posted June 15, 2008 Posted June 15, 2008 Jacob: That is one scary piece of equipment! What size channel is that, and how much force do you expect it can handle? I've got a pump and a jack, gauge etc but haven't come up with a press frame of any sort. FrankRizzo has modified his Hobby Fireworks press very nicely with a 3" cylinder. It presses some *damn* good rockets... when it isn't raining.
jacob Posted June 15, 2008 Posted June 15, 2008 Ha ha yeah it's real fun, when you crank it down hard the lights dim in my poorly powered pyro shop The channel is 3 1/8'' by 1 1/2'' I can't be sure but as a rough guess (and assuming the welds hold) I'd say 12 tons at least. I'd love to see some pictures of your press Frank.
psyco_1322 Posted June 15, 2008 Posted June 15, 2008 Nice, you might wanna make a stand while your at it. Unless you like pressing rockets on the floor
jacob Posted June 15, 2008 Posted June 15, 2008 Actually I kinda do, it's not very comfortable but it decreases the potential energy if I drop something, plus the cylinder alone weighs 50lbs (which also makes it top heavy ) so the closer to the ground the better IMO.
MilkyJoe Posted June 20, 2008 Posted June 20, 2008 hey... I am looking at getting a press but have no clue about them =P I have been looking at This 20 ton press Would this be suitable for pressing 1lb rockets and corning BP? How are these powered and what else would I need? I am guessing I could use an air compressor. I also noticed it has no gauge, how hard would it be to set this up? thanks ~Milky~
rocket Posted June 20, 2008 Posted June 20, 2008 It will be able to press 1lb rocks and easily press BP pucks. with the set up as is it now whether it suitable I don't know. Its a hand powder hydraulic jack so you have to pump it buy hand. You can put a gauge on it but i dont know how easy/hard this would be. They can be picked up cheaper than that ebay listing btw http://www.machineryhouse.com.au/Products?stockCode=P144
psyco_1322 Posted June 20, 2008 Posted June 20, 2008 A guage can be bought here, long with good tooling: http://www.wolterpyrotools.com/?page=cc_catg&cat=rocket
Rob Allen Posted July 16, 2008 Posted July 16, 2008 Sorry guys, being lazy today... I'm sure I might find this if I looked but when pressing your rockets how long do you leave the pressure on, just till you've compressed your fuel or do you leave the pressure on for a period of time? I just made a press and I'm use to ramming my rockets, so yeah thanks if you can help, cheers.
Rob Allen Posted July 16, 2008 Posted July 16, 2008 Also when pressing do you press small increments at a time like when ramming, or can you fill your tube all the way, press and fill again and so on till full?
TheSidewinder Posted July 17, 2008 Posted July 17, 2008 When pressing, use the same (small) increments that you'd use when ramming. The general rule is no more than 1/2 of an ID increment at a time. So, for a 1-inch tube, pour in an increment no "taller" than 1/2 an inch, uncompressed. The rocket makers I've personally observed don't hold the pressure on, they just press to the desired force, then release.
Rob Allen Posted July 17, 2008 Posted July 17, 2008 Thanks again.. the Press I have can leave the pressure on, do you think if I left it on for a period it would give better results, or pretty much the same?..
Frozentech Posted July 17, 2008 Posted July 17, 2008 I don't bother with dwell time on rockets, but on other items like BP pucks that I press, or comets, I do allow dwell time of about 45 seconds.
cplmac Posted July 27, 2008 Author Posted July 27, 2008 Yeah no dwell on rockets, but dwell on pucks, comets and crossettes. I sometimes give my press a second or so to settle, but if it's holding pressure under dwell for more than a couple seconds it's good to go. Sidewinder you meant half the ID when compressed right? I've never used an increment as small as half the ID uncompressed.
TheSidewinder Posted July 27, 2008 Posted July 27, 2008 Well, when ramming, I use half an ID uncompressed. Personally, I've had nothing but trouble if I use more than that. (Though I admit it could be my technique at fault.) By restricting myself to an uncompressed half-ID, I don't get any CATO's. And that's with pretty hot BP fuel. 70-20-10 (+5 Dex). All of them have been 8-ounce or smaller rockets. Whether that has anything to do with it, I'm not sure. I have zero experience with pressing, except for a couple rockets I pressed at the PGI in 2005. What I know is all theoretical, learned here and at the WPAG meets. I actually DO have a press, bought from a WPAG member, but it's sitting in my garage waiting for a suitable bench to mount it on. EDIT: And what the hell were you doing up at 3:55 am, LOL.
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