DIY pneumatic press for welding table

[drummerdimitri]

So I'd like to make a pneumatically activated cylinder press that would be mainly used on my Siegmund welding table to pend metal bars and pipes.

They sell one that is manually activated but it costs 1,800$ which is ridiculous even for them

The only issue now is finding a suitable air cylinder for the job since there are so many variables here such as single vs dual cylinders, bore size and stroke length etc.

Not sure how much fore would be required for my application but the Siegmund one is rated at 2.5 Tons and it seems the most powerful pneumatic ones go up to one ton or so at 145 PSI of inlet pressure which is the native pressure in my air compressor's tank.

Would this do the trick:
https://www.aliexpress.com/item/4000001144805.html?spm=a2g0o.cart.0.0.63a03c00boyzId&mp=1

 

[matt_i]

Personally I think you should design the process (tooling & guides for the tooling) first.

Then you will know what bore & stroke air cylinder to buy.

Before you get too far, I think a hydraulic press will better serve you as its capable of the tonnage needed to do work on things built of more than sheetmetal.

I would even take a mechanical compound leverage arbor press over an air cylinder press.

Unless you intend to do production-style light duty work like installing snaps, fabric or leather rivets, crimp terminals on wiring, I think you'll do better with hydraulic or mechanical. Don't attempt to use the air cylinder's rod-end guide as a tooling guide unless its really light duty, every air cylinder should have some sort of misalignment coupler at the end of the rod.

If you do end up with an air cylinder, item #2 to buy is flow controls for both ports. An air cylinder slams with impressive force if your valve is "digital" and gets snapped open quickly like you'd have in a spool or poppet valve.

 

[drummerdimitri]

Personally I think you should design the process (tooling & guides for the tooling) first.

Then you will know what bore & stroke air cylinder to buy.

Before you get too far, I think a hydraulic press will better serve you as its capable of the tonnage needed to do work on things built of more than sheetmetal.

I would even take a mechanical compound leverage arbor press over an air cylinder press.

Unless you intend to do production-style light duty work like installing snaps, fabric or leather rivets, crimp terminals on wiring, I think you'll do better with hydraulic or mechanical. Don't attempt to use the air cylinder's rod-end guide as a tooling guide unless its really light duty, every air cylinder should have some sort of misalignment coupler at the end of the rod.

If you do end up with an air cylinder, item #2 to buy is flow controls for both ports. An air cylinder slams with impressive force if your valve is "digital" and gets snapped open quickly like you'd have in a spool or poppet valve.

Thanks for the advice.

You're probably right, to get the tonnage I would require to do some heavy duty bending on steel and stainless steel, a hydraulic system would be much better suited for my application.

I will eventually make my own hydraulic press but this is a separate project as I'd like to be able to have more control in the bending process hence the horizontal press since the table acts as a guide in case the bending goes out of whack.

Are there similar looking hydraulic cylinders that I could use instead of the above pneumatic one? You know the one where you'd also need a hand actuated pump to put the cylinder outwards? That should do the trick.

 

[speed bump]

To get 2.5 tons of force at 120 psi are looking at least an 8" diameter cylinder. The cylinder you have in your link is only going to be good for 1200 or so ft-lbs all things considered.

What you want is a pneumatic over hydraulic cylinder. Things to consider, you need to know your stroke length and the amount of force you need.

 

[BukitCase]

Dimitri, the advice given so far is not only "better", it's the ONLY way you'll get enough force to bend steel, moreso for stainless -

I have this press (earlier model, same tonnage)

https://www.harborfreight.com/20-ton-shop-press-32879.html

and I replaced the hand operated 20 ton jack with this one, as mentioned by SpeedBump

https://www.harborfreight.com/20-to...ack-95553.html?_br_psugg_q=air+hydraulic+jack

I'm in the process of fabbing a quick disconnect system for my Case 580B backhoe/loader, it's a 12,000 pound machine capable of lifting a bit over 2 tons with the loader - so I'm using nothing lighter than 1/2" steel, and one of the components needs to be a "U" shaped "hook" that's 1/2" thick and 3" wide, to mate with 1-1/2" diameter loader pins -

The two items in above link are JUST BARELY capable of that task; I know, because in order to finish the "push" with the bending jig I made it needed a couple squirts of oil on the mouth of the jig.

The jig is made of 3/4" x 3" flat bar (mild steel), the press plates are 1" thick steel, and because I did NOT weld ACROSS the jig's base, the 2 legs of the "U" came out perfectly parallel.

Part of my point is this: If I had had any LESS than 20 tons, this wouldn't have worked - here's a few pics to clarify my explanations - ... Steve

 

[BukitCase]

A couple more - depending on YOUR version of what's "heavy", could be helpful; Also, nearly ALL hydraulic jacks (air over or not) can be used on their SIDE, but you need to orient the jack so its PUMP is lower than the cylinder. BTW, the "air over" doesn't give you any more "push", but these jacks are INCREDIBLY SLOW to pump by hand - the "air over" lets you "sneak up on" the push WITHOUT your arm hating you - then, if you need precision you can FINISH the push with the jack handle... Steve

 

[drummerdimitri]

Alright thanks for the feedback.

Seems like the pneumatic option is out of the question so there is no need to invest in a press specifically for my welding table as it would be redundant.

Will most probably just detach the cylinder from the Hydraulic Press and build some kind of contraption to fit it onto my welding table for when a job requires it to be so.

 

[trs71]

Dimitri, the advice given so far is not only "better", it's the ONLY way you'll get enough force to bend steel, moreso for stainless -

I have this press (earlier model, same tonnage)

https://www.harborfreight.com/20-ton-shop-press-32879.html

and I replaced the hand operated 20 ton jack with this one, as mentioned by SpeedBump

https://www.harborfreight.com/20-to...ack-95553.html?_br_psugg_q=air+hydraulic+jack

I'm in the process of fabbing a quick disconnect system for my Case 580B backhoe/loader, it's a 12,000 pound machine capable of lifting a bit over 2 tons with the loader - so I'm using nothing lighter than 1/2" steel, and one of the components needs to be a "U" shaped "hook" that's 1/2" thick and 3" wide, to mate with 1-1/2" diameter loader pins -

The two items in above link are JUST BARELY capable of that task; I know, because in order to finish the "push" with the bending jig I made it needed a couple squirts of oil on the mouth of the jig.

The jig is made of 3/4" x 3" flat bar (mild steel), the press plates are 1" thick steel, and because I did NOT weld ACROSS the jig's base, the 2 legs of the "U" came out perfectly parallel.

Part of my point is this: If I had had any LESS than 20 tons, this wouldn't have worked - here's a few pics to clarify my explanations - ... Steve

I'm 100% for diy fabbing, but when $100 ish options are out there...Chineese or not;

PS That is some heck of a good welding and fabrication job!!!

 

[BukitCase]

Thanks TRS - there were a couple times when even my MM252 had to turn its fan on :=)

Downside: those pics were taken just over 10 years ago, and the project STILL isn't finished. I'm constantly reminded of a saying that's been credited to John Lenon - "Life is the **** that happens to you while you're busy making plans", along with "Man plans, God laughs" (don't know the origin of that one)

Good thing I'm a Taurus (with 76 years practice at being stubborn) 'cause I'll only give up AFTER they "pat me in the face with a shovel"

In my defense, that "project" includes converting several implements besides just the loader - the list (either fabbing OR mount changes) includes a fork lift attachment, brush forks mount, 6' grapple mount, 6'x8'x2' tall brush bucket mount, 3PH adapter, SSQA adapter...

The "GOOD" news - REGARDLESS of when that "shovel pat" happens, it's pretty safe to say I will NEVER have been BORED ... Steve

 

[Bondo]

Are there similar looking hydraulic cylinders that I could use instead of the above pneumatic one? You know the one where you'd also need a hand actuated pump to put the cylinder outwards? That should do the trick.

Ayuh,..... Start here at Surplus Center,.....
'n the cylinders don't care what you use for a pump,....

 

[rsanter]

Buy a cheap porta power.
Then buy the air over hydrolic pump.

If you have a number of placement holes in your steel table and then you make a series of pins and guides you should be able to figure out how to bend about any shape of moderate thickness