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Air over oil.


Wayne V
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Hi folks

 

I want to start putting a Hydroulic press together and got a bit of a rude awakening when I saw what the power pack was going to cost. I have been trying to research an Äir Over Oil" system. Does anybody have experience with this?

 

Regards

Wayne

Our deepest fear is not that we are inadequate

Our deepest fear is that we are powerful beyond measure.

It is our light, not our darkness, that most frightens us.

We ask ourselves, who am I to be brilliant, gorgeous, talented and fabulous?

Actually, who are you not to be?

You are a child of God

Your playing small doesn’t serve the world.

There’s nothing enlightened about shrinking so that other people won’t feel insecure around you

We are born to make manifest the glory of God that is within us.

It’s not just in some of us; it’s in everyone.

And as we let our own light shine, we unconsciously give other people permission to do the same.

As we are liberated from our own fear, our presence automatically liberates others.

 

Nelson Mandela – 1994 Inaugural Speech.

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Wayne,

 

Are you referring to the mini press or a larger version? If you want to build the mini press you will need a 20 ton air over hydraulic jack available from Harbor Freight or Northern Tools in the US or a European source. I have seen a few other posts from people in your part of the world and they indicate finding the right jack is a challenge. Shipping costs seem to be the major show stopper for them because the jacks are heavy. If you haven't already, look at the pinned thread on the mini hydraulic press in this forum. You might also check the British Blades forum for further info.

 

Ken

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Once again I have been as clear as mud with my explainations.

 

Thanks for the heads-up on that thread.

 

I had something a lot larger in mind.

 

Here is my plan: According to some information I got hold of, If you expose a large surface area of oil to air pressure, then constrict the flow of said oil, say though a small pipe, you will end up with a high pressure hydroulic system. I'm not even sure this will work.

 

My press has been designed on that principal, untill someone tells me it's not true.

 

Here is a drawing of what I had in mind:

 

Press2.jpg

 

What I need to know is: Is this principal true? If so how do I work out my pressures, i.e. The ratios between the air pressure, surface area and final oil

pressure?

 

I think that if I can pull this off, I will end up with a fast, powerful press.

 

Regards

Wayne

Our deepest fear is not that we are inadequate

Our deepest fear is that we are powerful beyond measure.

It is our light, not our darkness, that most frightens us.

We ask ourselves, who am I to be brilliant, gorgeous, talented and fabulous?

Actually, who are you not to be?

You are a child of God

Your playing small doesn’t serve the world.

There’s nothing enlightened about shrinking so that other people won’t feel insecure around you

We are born to make manifest the glory of God that is within us.

It’s not just in some of us; it’s in everyone.

And as we let our own light shine, we unconsciously give other people permission to do the same.

As we are liberated from our own fear, our presence automatically liberates others.

 

Nelson Mandela – 1994 Inaugural Speech.

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Ah, I see! Not in my league since it's been many years since I took my last hydraulics/pneumatics course. From what I dimly recall, in the hydraulic world you can get power and speed by juggling the ratios around but unfortunately not both at the same time. Somebody else will have to fill you in on the details. Good luck with the project though.

 

Ken

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in your drawing it appears the oil pressure would be at air pressure

 

i am sure someone will be more familar with this type system

 

if there was 100 sq in of air to 10 sq in oil the pressure would be boosted 10X

 

this might be done thru a piston type setup oil on one side air on the other.

Edited by john marcus

infinite edge cutlery

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I bought such a system thinking that it would work and would have the advantage of being compact. What I got is an air over oil motor and cylinder from Enerpac. The motor is a box about the size of an old style computer monitor. You put 100psi in and you get 10k psi out. All well and good except...

 

I don't know if it is fast enough, and I never got to test it. It needs 18 cfm or about 30 gallons a minute to run. My poor little Craftsman huffer is running all the time and never really manages to get caught up. You'd need a big screw vane compressor to run this beast, or a couple of big accumulator tanks. By the time I got all of that sorted, I believed that it was cheaper to go a more conventional route.

 

This is just my experience with one such system, and so should be taken with some grains of salt.

 

Geoff

 

BTW, if anyone wants such a system, I have the motor and cylinder available. The motor is about 3k new, I'd take $1000 USD for both.

 

g

"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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I could be wrong, but I think most of the control valves for hydraulic cylinders need the fluid to recirculate to work right. To control the press, your setup might be more involved than your diagram shows.

 

Good luck with your project, Craig

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Mmmm I was hoping for pressure AND speed.

 

I am going to research this a bit more. Watch this space.

 

I have a little experience with hydroulics and although I may only know enough to be dangerous, as far as I know, the "recirculation system is only required if you are using a pump. (Power Pack). I may be totally wrong.

 

Geoff, thanks for the input, I will have to find out what the oil/air ratios are like and make sure that the required compressor doesn't end up costing much more than the power pack did in the first place.

 

Even so, the compressor has many more uses than the power pack and can earn it's keep.

 

Regards Wayne

Our deepest fear is not that we are inadequate

Our deepest fear is that we are powerful beyond measure.

It is our light, not our darkness, that most frightens us.

We ask ourselves, who am I to be brilliant, gorgeous, talented and fabulous?

Actually, who are you not to be?

You are a child of God

Your playing small doesn’t serve the world.

There’s nothing enlightened about shrinking so that other people won’t feel insecure around you

We are born to make manifest the glory of God that is within us.

It’s not just in some of us; it’s in everyone.

And as we let our own light shine, we unconsciously give other people permission to do the same.

As we are liberated from our own fear, our presence automatically liberates others.

 

Nelson Mandela – 1994 Inaugural Speech.

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  • 2 weeks later...

With an air/oil combo you might not get the speed you want. The 20 ton press I built can't be cycled very quickly compared to a double action hydraulic cylinder with a power pack.

But the air powered bottle jack cost $69 and generates enough squeeze for breaking down big bars at 90 -140 PSI air, compared to thousand(s) you'd spend on a cylinder, valves, power pack, tank, hoses.

In the bottle jack there is a piston type air motor driving a shaft connected to the hydraulic piston pump. At full air pressure it cycles 4-5 times per second with no load. There are power packs with vane type air motors driving hydraulic vane pumps, but these are going to cost more than comparable electric powered systems. I don't think they develop significantly more or less speed/power, they are just an alternative.

 

Now that I've been using the press for a while I want a 100# air hammer. I could get a lot more done with one of those.

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is there a reason you would want a press over a hammer...? its seems to me theres so much more that you could do with a forging hammer.... that being said....i would love ta have a press for hot punching lol

All these things shall love do unto you that you may know the secrets of your heart,and in that knowledge become a fragment of Life's heart...

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It's just my experience, but here you are.

 

A hammer is a violent impact, which, when you are worried about early stage welds coming apart, is bad. In addition, the most my 50lb hammer will handle is about 3 inches of stock. It takes me 4-6 hours of forging on the hammer to end up with a piece of steel 15 x 1.5 x .300 of 300 layers. I usually start with 8-9 pieces of .250 x 1.5 x 6 stock.

 

In a class I took a couple of years ago I got to work on a 20 ton hydraulic press. I was able to weld a 29 piece, .250 x 1.5 x 8 billet (7.25 inches tall) in a single pass, and reduce it to 1.5 x .500 x 36 ia about an hour and a half, and complete a 300 (ish) layer bar before lunch.

 

Don't get me wrong, I love having a hammer, I've done a ton of work on it since a buddy and I built it in 2000, but I think if I only had room for one big tool in the shop, I'd go for a press.

 

There are a bunch of damascus patterns that I would never attempt on a hammer, but, as I said, this is just my experience.

 

Geoff

"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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