Hydraulic Press for BP rockets

[jdurand]

I made this some time back for making my BP rockets, back when I had enough free time to be co-chair of manufacturing at fireworks conventions. Sorry, no photos during the construction.

Anyway, I got the smallest jack that would give the pressure I needed in the fuel and then put a gauge on it. Be sure to use rated hydraulic fittings, you're dealing with pretty decent pressures. The reason for the smallest jack is it pumps the fastest. Some guys go for bigger jacks and spend all their time pumping.

To get the jack apart, I used a strap wrench to unscrew the body and then drilled and tapped in from the side for the fitting. I drilled a small hole from there to the center of the jack and then drilled down from the top until the holes met. The drilling was done on my big mill/drill.

While you have it apart, be SURE to measure the diameter of the cylinder, you'll need that to calibrate the gauge!

Put it all back together and test it. Turns out I needed just under 3,000 psi on the gauge to press the black powder to 5000 psi.

You'll notice a window on the press, that's two layers of polycarbonate with wire between in a steel frame. Black powder rarely explodes when being pressed, I wanted to make sure I'd have a story to tell if it ever did. Now, the guys pressing whistle rockets are another matter...







This wasn't one of mine, I was just there as one of the safety guys and took a break to fill some launches.

[Altair]

Thanks jdurand! We've added your Rocket Hydraulic Press to our Miscellaneous category,
as well as to your builder page: jdurand's Homemade Tools. Your receipt:

Rocket Hydraulic Press by jdurand

tags: press, hydraulic

[jdurand]

BTW, for anyone making rockets, there's a secret told to me by a mad pyro who writes a column with his hat covering his eyes to protect the guilty...

When figuring your pressure, be sure to account for the fact your rocket has a hole in the middle that varies in diameter with depth. So, you need to start off at lower gauge pressure and increase to max by the top of the spindle used to form the core. That way it's all pressed with the same psi.