gizmothegecko Posted November 13 Posted November 13 Hi everyone. I'm looking at getting a 6 ton bottle jack to press some whistle and BP rockets. I'm aware that whistle rockets need specific PSI to work properly, but I'm not sure how I would achieve that with a bottle jack since you can't really control the PSI on it. Is there someway I can make it so I can control the exact PSI to keep consistent results when pressing? Any help is greatly appreciated.
FrankRizzo Posted November 13 Posted November 13 (edited) The "easy" way to do it is by using a P2F device under the tooling, and monitoring the gauge. You can make one from a small jack body adapted with a pressure gauge, but you need to do a little measuring and math to figure out a gauge reading to force table. If you've got a few bucks, both Ben and Woody make a nice one. https://www.woodysrocks.com/store/p86/Pressure_to_Force_Gauges.html#/ https://fire-smith.com/products-1/ols/products/pressure-conversion-tool DIY: Edited November 13 by FrankRizzo
FrankRizzo Posted November 13 Posted November 13 (edited) The intermediate way is to take your bottle jack apart, then drill and tap a high pressure passage, to add a pressure gauge to the jack body itself. The process is a huge pain in the ass. You need a large pipe wrench and well-anchored bench vise in order to disassemble the jack body. Searching YouTube for "bottle jack tap gauge" will give a good collection of videos detailing that process. You could potentially step it up another notch by doing the modification above, and adding an adjustable pressure relief valve with a return line back to the reservoir. Unfortunately, bottle jacks operate at 10,000 PSI when they are at their rated capacity, and finding a relief valve for that pressure range would be very expensive. Edited November 13 by FrankRizzo
DavidF Posted November 14 Posted November 14 Before investing in a bottle jack and making a press, you might consider another alternative. An arbor press is already a press, but would need some modification. A PtoF gauge could be used with it, but using a torque wrench is easier and faster. There are videos on YouTube of that modification process also. Torque wrench pressing with an arbor press is WAY faster than using a bottle jack. You can get air over hydraulic bottle jacks too, but then you need a compressor and still need a press (and a PtoF gauge). I'd compare the ins and outs of both options before committing any dollars. Arbor press with torque wrench= pull, click. Bottle jack (manual) = whacka, whacka, whacka, whacka, whacka for every increment.
FrankRizzo Posted November 14 Posted November 14 I agree with David. An Arbor press is much simpler to use. The caveat is that you're limited a bit on motor sizes due to the lower pressing force. You'll also need to raise it up on some threaded rod in order to get clearance for the tube and tooling. I've done up to 5/8" bore motors with mine.
gizmothegecko Posted November 14 Author Posted November 14 Thank you for all of the input, I think I will get a 1 ton arbor press and either make myself a force gauge or buy one. Ned Gorski has a tutorial on how to raise the press on threaded rod so I think I will do that for my next project. One last thing: I was looking online and saw that 3 ton arbor presses are being sold, would that be something to consider instead of a bottle jack when moving up to bigger rockets? Or would it just be better to get a bottle jack?
FrankRizzo Posted November 14 Posted November 14 (edited) A 3-ton press would get you into 1" bore (3lb) motors. It likely wouldn't allow you to run much in the way of star plates. A hydraulic press would get you into both. For the price, and physical size of a 3-ton arbor press, I think you'd be better off investing in a good hydraulic press. Edited November 14 by FrankRizzo
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