Press is not as powerful as it should be

[Deimos]

 

4 minutes ago, Chem said:

How big of a difference are we talking about? Enough to make a difference? As I understand a hydraulic piston, the pressure is diverted from one side of the ram to the other. Both lines and holes are the same size and the pressure is the same in both directions. The pump doesn't know which way the pressure flows. 

Over here it is about 50%, so it makes a lot of difference. If you change the design like this it will use the full force of the cylinder.

[JHCC]

The pressure is the same in both directions, but that doesn't mean both directions move with the same force. The force is determined by the pressure of the hydraulic fluid multiplied by the surface area that it's pushing against.

Let's assume for a moment that you have a 4" cylinder with a 2" rod, operating at 2,000 psi. When the ram extends, the fluid is pushing against the full area of the piston, which is a little over 12.5 square inches (4 x pi) x 2,000 psi = 25,000 pounds of force. When the ram retracts, the fluid is not pushing against the area covered by the rod, so you're only pushing against 9.36 square inches (12.5 - 3.14) x 2,000 psi = 18,720 pounds of force.

Make sense?

[Buzzkill]

Deimos, now we're on the same page.  For a while I thought I was missing something obvious that everyone else was easily understanding.  

[Chem]

1 hour ago, Deimos said:

Also switch the hoses. Just a question, the frame of the press, was that a home made or bought? Since I have a good idea why you are having trouble with the hydraulics, i also see some things in the design that bother me. Moving pieces where the pain is scraped is never a good sign.

Yes I built the frame out of a 6×6 1/4 I beam.I couldn't find ant tubing that fit the OD diameter of my 2" close enough,  so I plasma cut some plate and welded it together for my guides. I probably shouldn't have painted the top plate risers, but coastal Texas is brutal to exposed metal. There is some slight rubbing, as you can see from the paint, but the tolerances are not binding an any way. Any suggestions would be appreciated. 

[Deimos]

JHCC, since you can explain way better then me, can you also explain what the difference is in fluid volume in both sides of the cylinder and what that changes in speed and oil flow?

4 hours ago, Chem said:

Yes I built the frame out of a 6×6 1/4 I beam.I couldn't find ant tubing that fit the OD diameter of my 2" close enough,  so I plasma cut some plate and welded it together for my guides.

The cheapest I can think of right now is Teflon blocks on both sides of the moving parts. Teflon blocks are very very hard and wear resistant. 

[Chem]

Thank you.

[Frosty]

I'll get to as simple an explanation as I can in a moment Chem.

Guys, you couldn't use the ram push in this press without redesigning the press. Flipping the piston has ZERO effecct, it still MUST pull using the smaller area around the rod.

Chem: Reading how folks built a press online isn't research. Randy has made some good machinery but his designs are usually sub optimal, they work but not as well as they should. Sorry but you can't build with hydraulics without doing the math, it's not complicated math but it's as necessary as breathing.

The push side of your ram has 19.65 sq. inches of area. The pull side's area is partially taken up by the rod so you MUST subtract the area of the rod.  I do not know the diameter of the rod so am using 1.5" just so I can do the arithmetic, the real diameter if different will change the final numbers. The loss of area and force is a bit UNDER 10% so not a great loss. 

Make sense so far?

using 1.5" for rod diameter it has 1.77 sq in area. (I round numbers) subtract 1.88 from 19.65 you get 17.88 sq in. Your pump produces 3,000psi multiply that by 17.88 for the amount of force the ram can apply pulling in pounds, divide by 2,000 to convert to tons. your piston should apply 26.82 tons of force. Some will be lost to friction but it's not too insignificant. 26.82 tns. pull compared to 29.47tns. push.

 That's pretty decent force for a forge press, not great but decent. 

There are other factors that rob you of power. From what I read I don't think your fittings are too small, does your press squeal when you use it? You will hear the fluid flowing but it shouldn't be more than a hissing sound. 

Does your valve squeal? It'll be a little louder than the other fittings but shouldn't be much louder. 

The one thing I see on almost all home build presses that robs power is all the hoses, the longer they are the more power they absorb expanding when pressure is passed through them.  When you pull the lever you see the hoses move, yes? It takes considerable force to stretch expand a wire woven hydraulic hose, this is hydraulic psi that is subtracted from the system.

A fundamental principle of hydraulics is that the psi is exactly the same in the whole circuit. The circuit being the system after the last valve after the pump output. So any component that absorbs psi rather than transmits it is absorbing power.

Your pump has plenty of GPM, do NOT let folks confuse you by ram speed, hows and whys, this is NOT an issue on your press.

If you have a hydraulic pressure gauge it might tell us something if you can put it in the circuit near the piston.

One last thing Chem, I'm NOT going to get involved discussing this with the other guys in this thread unless they suggest something dangerous or. I'll be responding to you only and I won't spend much if any time answering your questions about other guys posts. I don't have the patience to rehash explaining all the mistaken ideas and guesses about hydraulics again. Some of the guys know enough about what they're talking about to get you up and working but I don't have the patience to get into another long round robin discussion if a fundamentally simple device. I'm a TBI survivor and literally don't have the patience, it's a common TBI issue. 

Frosty The Lucky.

[Chem]

4 hours ago, Deimos said:

Over here it is about 50%, so it makes a lot of difference. If you change the design like this it will use the full force of the cylinder.

I think you nailed it. I just did some measuring, and I will just have to make a few small modifications. I wish I would have talked to yall about this when I was in the original design phase. I literally thought about if there was a difference in push and pull, and figured it didn't matter too much. I got it WAY wrong. It was a priority for me that the press be as short as possible in overall height. 

[Deimos]

If you decide to shorten hoses, remember that as they are put under pressure they get shorter. And if they scrape against stuff they will go kaput very fast.

 

 

 

[Chem]

4 hours ago, Frosty said:

I'll get to as simple an explanation as I can in a moment Chem.

Thank you. Im pretty sure I can redesign my press without too much hassle.  I just somehow missed the whole push pull difference, and I actually gave it some thought in the original design phase. 

3 hours ago, Deimos said:

If you decide to shorten hoses, remember that as they are put under pressure they get shorter. And if they scrape against stuff they will go kaput very fast.

I found that out yesterday when my backhoe blew a hydraulic hose three feet from me. That is not a pleasant experience. 

[Deimos]

Yup, that is a very wet and unpleasant experience. I hope nothing got damaged or hurt?

[Nobody Special]

3 hours ago, Frosty said:

I'm a TBI survivor and literally don't have the patience, it's a common TBI issue. 

Also the wild emotional swings, loss of impulse control, easy distraction, aphasia in areas that use to be easy...it's the gift that keeps on giving.  My wife is a TBI survivor (kicked in the head by a horse), and goes into a blind rage about five times a week or so.  Can be for good reasons or lousy ones, may last 5 minutes or 50 until the circuit breaker resets, thinks it's perfectly logical until it's over, then sometimes doesn't even know remember it.  I can't count all the times she threatened divorce, and she actually got to the courthouse and filed papers twice before she came back to herself.  Home schooling the kids over COVID ain't helping any. 

 

Then there's my military buddies with 'em....Thank God, I only came back with PTSD (and that ain't sarcastic).

[swedefiddle]

Good Morning,

The surface area is greater on the side with no ram. Lbs./sq.Inch means per square inch. You have to deduct the area of the ram, from the surface area of the piston. Surface area is Pi x Radius x Radius (3.1416 x R2). The pump working pressure X the sq/in = actual Press working pressure. Hydraulics is Mathmatics.

You say the Press doesn't work as you thought it will. What are you comparing to? Pump and Cylinder are part of the equation. If you want more pressure, adjust your relief valve for more pressure (your cylinder isn't rated for more pressure) or use a larger cylinder. If you want more speed, use a smaller cylinder or a larger pump. The cylinder you have is rated for a certain pressure, you may want to use a cylinder that is rated for more pressure. If you make your Dies smaller, you get greater lbs./sq.Inch. More pressure means problems will happen at bullet speed. How do you dodge a bullet? Work SAFE!!!!!

Neil

[Chem]

The guys here explained that my system would get more "crush force" if I make an adjustment to the press frame. I am planning to modify the press so that the cylinder work is done with a push (cylinder extending), instead of the pull (retracting) that I have now. As for smaller dyes, I plan to make many more for a broader range of tasks that I need. Currently I have sets of flat, squaring, and fullering dyes. That just covers me with the bare basics for now. I  have more work than I can handle right now. This press will surely speed up my productivity...  As soon as I make the modifications. 

[pnut]

I found a free pdf of a book on z library that might help. It's titled hydraulic system design fundamentals. Here's a link. I think I'm allowed to post it. If not I'll find the ISBN number for you and complete title and you can still get it. https://1lib.us/book/2515254/a19ed2

Pnut

[Chem]

Awesome, thanks 

[Frosty]

17 hours ago, Nobody Special said:

Also the wild emotional swings, loss of impulse control, easy distraction, aphasia in areas that use to be easy...it's the gift that keeps on giving.  My wife is a TBI survivor (kicked in the head by a horse)

Ayup, all of that though happily I don't fly into rages but I get angry at the drop of a hat. Fortunately my emotions are quick but not extreme. When I do get angry, especially at someone, I stay angry, sometimes for months. The trick that works sort of well is to just walk away if someone is ticking me off before I get angry. I still get angry just not so bad. 

Another trick is knowing when you're in a danger area. I make lists to go shopping and don't look at the nifty gadgets or ads. Occasionally I'll deliberately go impulse shopping, usually for dinner but I'm filling a menu so it's not pure impulse. 

I've had to develop a lot of tricks to cope and they work, usually. Avoiding trigger situations is #1.

Frosty The Lucky. 

[Deimos]

Well, as someone with Autism I kind of understand how you feel, I wish I learned sooner to just walk away when I fell into anger.

[Irondragon Forge ClayWorks]

21 hours ago, Chem said:

my system would get more "crush force" if I make an adjustment to the press frame

I kept thinking that but because the only experience I have with hydraulics is with my tractor & log splitter, I wasn't sure. The more I thought about it the more my head hurt and I'm glad the experienced folks confirmed that.

[JHCC]

On 12/4/2020 at 3:39 PM, Deimos said:

If you decide to shorten hoses, remember that as they are put under pressure they get shorter. And if they scrape against stuff they will go kaput very fast.

Another good option is to replace the hoses with metal tubes and flare fittings, so long as they're rated for hydraulics. That eliminates pretty much all the flex.

[Chem]

9 hours ago, Frosty said:

Ayup, all of that though happily I don't fly into rages but I get angry at the drop of a hat. Fortunately my emotions are quick but not extreme. The trick that works sort of well is to just walk away if someone is ticking me off before I get angry.

You must be an incredibly strong person to not only deal with your challenges like you do,  but to talk about them openly. It is so important to talk about our hardships,  but most of us compartmentalize the problem. That works for a while,  but no man is a rock forever. Sooner or later handling stresses alone ends up with a less than desirable experience for everyone involved. 

[Chem]

Another trick is knowing when you're in a danger area. I make lists to go shopping and don't look at the nifty gadgets or ads. Occasionally I'll deliberately go impulse shopping, usually for dinner but I'm filling a menu so it's not pure impulse. I've had to develop a lot of tricks to cope and they work, usually. Avoiding trigger situations is

I don't think I will change the press body after all.  I took a tape and a scratch pad to the press and realized it was going to be a lot more complicated than I thought. The press does put out a moderate amount of power now. Almost enough for my needs. The fullering dyes do move metal, but It just doesn't do enough with flat and squaring dyes. I've decided to get a 10 hp single phase electric motor,  to get me over the hump. I also thought about a 7.5 hp motor,  but with the larger motor I'm positive it willi be more than enough. If I have too much force, I can always back off the pressure relief valve to exactly where I want it.

[JHCC]

1 hour ago, Chem said:

You must be an incredibly strong person to not only deal with your challenges like you do,  but to talk about them openly.

One thing about IFI is that we as a community are pretty open about our respective mental health challenges, be it TBI, depression, ASD, or simply being obsessed with blacksmithing. 

[Glenn]

Simply being obsessed with blacksmithing is mental health challenge ??

[JHCC]

Like they say, I don’t struggle with mental illness: I welcome it!