Hydraulic Power Pack Driven Press
See rockets/presses.html for general information about hydraulic presses
Power packs make quick work of pressing rockets and and other devices. Many of the PGI crowd (and others) swear by them and if you watch one in action, it is very cool. It takes no time to press up a rocket with one of these.
All fittings were 3/8 NPT except the gauge which required a 3/8 to 1/4 reducer. If you live near a supplier, it is best to just walk in and choose the pieces needed so you walk out with a solution. However, you can still make it all work if you are careful. Here is a list of materials (most from Surpluscenter.com):
note that you can use a double acting cylinder and pack - the cost might not be much more - no spring return needed if you do that
1. Power Pack ( 12 VDC 2500 psi single action) with handle
2. Wood for stand
3. 12 volt marine battery and charger (lasts quite a while on a charge)
4. 10' of 3/8 hose
5. T fitting coming out of power pack for gauge
6. 0-3000 oil filled gauge
7. Reducer to put gauge on T fitting
8. Hydraulic fluid (five gallon jugs are common and you need about half that to fill the pack)
9. Single action cylinder (2 9/16 piston) - try to get a cylinder around 2.5 inches. Much less and you won't be able to press bigger rockets. Much more and it will be hard to press smaller rockets. For instance, with a 3" cylinder, each increment on the power pack gauge is worth 700 pounds on the ram - which equates to about 2000 pounds on a 5/8" motor! If you bump the switch just a fraction hard, you have crushed a 5/8" motor. If you use a 1.25 inch cylinder, you won't have enough force to press anything over about 5/8"!
10. Press frame (I used my Harbor Freight version) with spring return
11. Cables for battery (standard car cables work great - get 50 inch ones)
12. 3/8" NC bolts to secure power pack to stand.
13. Small piece of sheet metal for top of stand to make it oil proof.
14. Gasket sealer to seal pack to the metal top and to seal the metal top onto the stand (optional)
11. Teflon tape, screws, nails, and rags to clean up the mess you will make (;-})This one is a single action cylinder and power pack so it has to have a spring return on the stand itself. It runs on a 12 volt marine battery and it was hooked to my current Harbor Freight press to save on building another. If your cylinder is beefy enough, just substitute the cylinder for the jack - this one has some angle iron on the bottom to prevent a kickout. Cost for the new power pack, gauges, hose, fittings (needed a T fitting for the gauge), fluid and cylinder was $570 - so it ain't cheap and a normal press will do just fine for all things... but ain't it cool?
Typically, H frame presses like the above will twist and sometimes cause the ram to slip or cock to one side. The following is a reinforcement for the H frame to stop it from twisting under heavy loads. It is easy to do and makes the whole pressing process much nicer. In addition, the main bolts holding it all together were tightened to maximum torque - which also helped a lot. Note that a cap was added to the top of the cylinder (compare the photo below to the one above) to prevent a kick-out at the top. The cap fits inside the press mount and outside the inner cylinder.
Also, this press is REALLY efficient and it is hard to press smaller items on it (much harder than with a normal hydraulic press). With just 500 pounds on the power pack gauge (given the 2 9/16" cylinder), a 5/8" tube will feel about 8,000 pounds force! The press tends to crush smaller motors - unless you use iron/steel reinforcement sleeves on the tubes. For 5/8 motors - which are about the smallest you want to press - I've made reinforcement sleeves from iron water pipe (sliced like a PVC tube) with the inside smoothed out on the lathe. They work great but you need a blast shield - if one pops, there will be shrapnel.
Here is an example 5/8" sleeve:
Below is my Marvin the Martian Shield From Hell - 180 pounds of steel steam door cover. In case of an "Earth Shattering Kaboom" it will stop the shrapnel.
This whole setup is meant for larger rockets and even they need sleeves - but once you get the knack of it, you can make consistent and reliable motors very quickly.
