Press

[Rob Allen]

I've just made a 2 ton hydrolic press, but I was wondering would a compressed air, press, up to 180psi be better?

[TheSidewinder]

The hydraulic press, hands down. You should also have some sort of pressure gauge. Knowing the pressing force, on the grain itself, is important. Most of this info is already here, and we do expect members to "do their homework" with respect to using the search feature. Read all the threads you can find on presses and their use. It will be more educating than what anyone can type in one or two responses, anyway.

 

Thank you.

[Rob Allen]

Gee you must be bored answering all my questions, I did search and read through most of whats on here but I must have skipped the part about the air press Sorry... I'm sure the one I have now will work great.. Time will tell

 

Cheers.

[Swede]

They make hydraulic bottles that used compressed air to turn a tiny hydraulic pump, which in turn actuates the bottle... is that what you were referring to? Plain old 180 PSI air alone on a piston or ram wouldn't do squat for pyrotechnic use.

[TheSidewinder]

Gee you must be bored answering all my questions, I did search and read through most of whats on here but I must have skipped the part about the air press Sorry... I'm sure the one I have now will work great.. Time will tell

 

Cheers.

It's not boredom. It's just that all your questions (except one) have been asked and answered here before, and sometimes dozens of times.

 

We DO understand the enthusiasm of newcomers to the hobby (we were ALL there at one time), and the sometimes-difficult job of finding answers to your questions.

 

But the best advice I and others can give you is to spend a fair bit of time reading the existing threads, taking notes as you go, and THEN ask for clarification on things you still don't understand.

 

This hobby is definitely NOT for the impatient. That leads to carelessness, and carelessness leads to accidents. Far too many people these days (young AND old) expect that everything be handed to them instantly, and that all one needs to do is ask for it. We call that "spoonfeeding", and simply won't tolerate it. Not because we're being unkind or selfish, but because we want all the hobbyists to understand what they're doing BEFORE they get themselves in trouble, be that physical or legal. After all, we're working with chemicals, compositions, and devices that could KILL you if you mishandle them or misuse them.

 

That said, no need for an apology. Just research the site, and you'll find answers to almost any question a newcomer can ask.

 

Enjoy, and be safe.

[Rob Allen]

Sidewinder, cheers.

 

Swede yes you know what I ment, I think that using that with a gauge would have better control that a lever pump, I know you can add gauges and there are various sites on where to get them. I'm not keen on adding it to my bottle, I think the compressor powered ones are too expensive.

 

I guess I'll have to just stick to my lever powered bottle... I pressed a rocket for the first time last night, not exciting for anyone else I know but I wont be ramming any more thats for sure. I probably tripled if not quadrupled the flight, insane! It would be fair to say if the moon didn't move out of the way at the last minute I would have hit him

[TheSidewinder]

See, you're discovering things already.

 

Pressing is far superior to ramming in almost every case, as you've found out. Well-pressed BP rockets, though simple, can be downwright addicting.

[Rob Allen]

cant win em all.. Just let another one off and flew like a mother but skidding along the ground, bugger. Gonna have to hit the drawing board over a again the engine was most likely too long I made it half an inch longer.

[Swede]

Rob, for the reasons you mentioned (control over the pressing) I bought one of those air-powered hydraulic bottle-jacks to retrofit to my H press.

 

Here's one from Harbor Freight, not bad at $80 for a 20 ton job.

 

http://www.harborfreight.com/cpi/photos/95500-95599/95553.gif

 

It's still in the box right now. My hope is this - connected to a precision air regulator, I am hoping that if I apply "X" PSI to the input, the ram will move and press, and then at a certain compression of the rocket fuel, will stop. I think it will work, and might be as good as tapping a jack for a true hydraulic pressure gauge, which is a real pain. By taking notes, you could create a recipe for a given rocket, such as "55 PSI with this tooling will work for an 8 ounce rocket"... something like that. We'll see if it works.

[Rob Allen]

Holy crap that's exactly what I want! The spring idea is cool, so much better than having to push it back in yourself.

 

It does work in the same way in respect to small amount of effort used with the lever to achieve high pressure right. it doesn't require huge pressure from a heavy duty compressor to push the hydraulic fluid in the jack directly does it? That would defeat the purpose.

 

Should work a treat. I'm gonna have to check out that link.

 

Cheers, let me know how it goes!

[Rob Allen]

Should 'av checked the link first, yeah operating 90-120psi wow I getting one!

[FrankRizzo]

Rob, for the reasons you mentioned (control over the pressing) I bought one of those air-powered hydraulic bottle-jacks to retrofit to my H press.

 

It's still in the box right now.  My hope is this - connected to a precision air regulator, I am hoping that if I apply "X" PSI to the input, the ram will move and press, and then at a certain compression of the rocket fuel, will stop.  I think it will work, and might be as good as tapping a jack for a true hydraulic pressure gauge, which is a real pain.  By taking notes, you could create a recipe for a given rocket, such as "55 PSI with this tooling will work for an 8 ounce rocket"... something like that.  We'll see if it works.

Sorry to be the bearer of bad news, but unfortunately it won't work the way you intend it to. The air/hydraulic unit on the back isn't a hydraulic intensifier, it's some other weird pump mechanism. The only thing that changing the line pressure will do is make it pump up to the 10,000 PSI painfully slowly. I messed with mine for a few weeks until just saying fuck-it and buying a power-pack and cylinder setup with fully adjustable relief.

[Rob Allen]

that sucks

[crazyboy25]

I messed with mine for a few weeks until just saying fuck-it and buying a power-pack and cylinder setup with

How is that different from that? That press Swede linked seems ideal 20 tons and all you do is hook it up to a air compressor push the lever and release and the spring release brings it back.

[tentacles]

The air over jacks can work, but you would need a gauge in the jack (not very difficult, really) to read the pressure, or a Wolter force gauge. But if you go with the Wolter force gauge, why not just buy a power pack + pressure gauge and be done with it?

[TheSidewinder]

Yeah, you really do need some type of direct-force gauge to know what your actual pressure on the grain is. The Wolter gauge is pricey, but VERY well-made.

 

As an aside, I read that the Wolter's won't be at the PGI this year. That's too bad. I know some folks out West that were looking forward to meeting him and saving the shipping cost for his products.

[FrankRizzo]

I messed with mine for a few weeks until just saying fuck-it and buying a power-pack and cylinder setup with

How is that different from that? That press Swede linked seems ideal 20 tons and all you do is hook it up to a air compressor push the lever and release and the spring release brings it back.

I'm not saying that you can't press rockets with it. I used the air/hydraulic jack supplied on my Hobby Fireworks large rocket press for 2 years, and loved the fact that I could just open the air valve, and chug-chug-chug up the piston went. What I didn't like, and what problem Swede wanted solve with the precision regulator, is that you have to constantly watch the pressure gauge to avoid under/over pressing your device.

 

An electric hydraulic pump has an adjustable relief valve that lets you *set* the hydraulic pressure. Once the the set pressure has been reached, the extra oil just bypasses the piston circuit and goes back to the reservoir tank. I can press the remote all day long, and if I set the relief to 500PSI, the piston will only travel up enough to contact the work and exert a controlled amount of force and nothing more. If you held open the air valve on that jack however, it would slowly increase the force all the way to the jacks' maximum rating. Obviously you can see the advantage.

 

Also, using air pressure justs adds another piece of equipment to the power train. It's much more efficient (electrically and mechanically) to use electricity to drive a hydraulic pump directly.

[Swede]

Frank, thank you for ruthlessly crushing our dreams of cheap and repeatable hydraulic tooling!

 

How about this - a traditional bottle jack is a pain to tap for a pressure gauge. it can be done, and Passfire tells us how, but it looks to be a royal PITA. With this air-driven bottle, would there be an easier way to tap the system and read hydraulic pressure directly? I was hoping that the air motor was a true hydraulic power pack, and there'd be a high-pressure liquid hydraulic line connecting pack to bottle. Not true?

[Aquarius]

Q @ Frank R: "An electric hydraulic pump has an adjustable relief valve that lets you *set* the hydraulic pressure".

 

I have just sent my hydraulic press system away for welding. It is a reworked hydraulic garbage press, complete with a two-way hydraulic oil system, lever etc. The only thing I don NOT have, is a way to read or control the pressure beeing applied. No, the relief valve interest me. If I have one (wich I think I have, but unable to check..), where would it sit?

 

If I remember correctly, there's something resembling a nut on the "lever-thingy". Is that a possibility? And I wonder if it ain't something similar looking on the power pack.

 

Thanks, will try to get some pictures to clear thing up if it's hard to understand.

[FrankRizzo]

Swede: Some of those jacks have gauge ports already installed, but the models that are sold without the gauge attached have a plug that just needs to be removed. There is something that looks very similar to one of those plugs on your picture, near the output of the air/hydraulic module. Mine was disassembled and drilled/tapped by the guy at HobbyFireworks before I bought it.

 

http://pyrobin.com/files/95553.gif

 

 

Aquarius: The relief valve is usually a flat-head screw that you either screw in/out to adjust your pressure. Sometimes, the screw is under a protective cap that needs to be unscrewed first. Mine is on the power pack itself. In fact, I've got two..one for each line.

 

Your gauge will go inline with the hose supplying the bottom of your cylinder. Just install a hydraulic tee fitting, and attach the gauge.

[Swede]

Hi Frank, I finally got around to opening that 20 ton air jack from harbor freight, and messed around with it a bit. You are correct, I sure can't see any way of creating a variable ram press by messing with the air motor. You are also correct on those ports, there are no less than three of them on the base, surrounding the air motor. One of them can probably be "teed" and fed via a hydraulic flex line to a gauge - or just mount the gauge right on the base with a brass ell fitting.

 

The air motor makes an interesting chugging noise, like a steam engine, but the ram moves smoothly. Impression: This is a slick setup. Anyone making a press, with compressed air available, I'd recommend one of these as being much superior to a hand-jack. I am going to attempt a retrofit to my cheap H-press.

[Swede]

Quick update on this beast... there are no less than five threaded ports into the base and body, one each for the hand and motor pumps, and three in the back. Each of them has springs and balls, and forms a portion of the valving. They are either check valves or flow valves. None of them AFAIK is directly connected to the high-pressure hydraulics in the jack.

 

I thought perhaps removing a ball and spring would allow the high-pressure fluid to impinge on a pressure gauge, but the threads are NOT standard hydraulic threads or female taper pipe, they are metric, and I had no fittings that could work with them.

 

I probably spent about 3 hours on it, and in the end, gave up and restored it to its original condition. At least it fit perfectly in my press, so now I have a cool air-powered press, rather than a hand-pumped one. To summarize, there is no easy way to tap one of these air bottles for a pressure gauge.

[DeepOvertone]

I looked at every jack my local harbor freight had and I couldnt find a single one with a high pressure tap for a gauge. I decided to go with the guage rich wolter sells. I called him and he said that its more acurate to measure it that way anyway. Looks like a super product IMO. I also looked at the H presses at Harbor freight. I didn't like the long rod attached to the beam under the jack. IMO it looked as though it would be hard to line up that rod with the rocket tooling. I would prefer it not be there at all. Also, the rod was bent on the display so that says to me it may easily bend if you aren't careful. I've heard that the beam that the jack rides on isn't very stable anyway, and may skew off to one side while pressing... Is this true? Should I look to make one instead? I was thinking about using some allthread and I-beam to throw one together.. Any thoughts? What do the pros like cplmac or laduke use? $1000 presses?

[jacob]

Check out this thread, laduke I believe uses a power pack and two way cylinder setup, like this,

http://www.pgi.org/PGI2007/images/P8060171.JPG

(^On the right)

Or this.

http://www.pgi.org/PGI2007/images/P8060172.JPG

(^I think that's laduke himself)

 

 

I definitely recommend building your own press, but be carefull, threaded rod has a tendency to bend if not reinforced properly, actually you don't even need metal, you can make it out of wood if you like.

 

And yeah a pressure gauge is a great thing to have, really helps consistency.

[Mumbles]

That would indeed be Mr. LaDuke himself. He tried to explain how to build a press once. After about 3 words I just nodded and agreed as I had no idea what he was talking about. Probably like he would do if I ever tried to explain something about chemistry to him.