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I'm making a press brake so I can form my own sheet metal parts. I'm debating on placing two hydraulic jacks like a normal shop press. Or using one jack behind or to the side of the press to use a cantilever/Bell crank type arm to create the downward motion.

I figure if I use the cantilever type design, I could double or triple the ratio and be able to use just one hydraulic jack to get the same (or close to) press force.

These are the jacks I would be using. (Hopefully just 1?)

http://www.harborfreight.com/20-ton-air ... 95553.html


The press brake will have a capacity to fit a 30" sheet. And easily bend that full length up to .125" 5052 Aluminum. I highly doubt I would bend any steel longer than a small bracket, maybe 2"-4", and not thicker than 3/16". And doubt even stronger I will do stainless anything.

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Plans: Single Rotor turbo sub 1000lb machine!

here's a picture of the press and die as I have it now. I'm working on the body and other parts.

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Plans: Single Rotor turbo sub 1000lb machine!

I think you may run into an issue with equal force distribution on thicker sheets if you only used one jack that was not mounted in the center.

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Tucker

This is the basic design as of right now. Still need to add return springs and other misc. items. The jack would sit above the punch and press against the top to create the downward motion. Just like a normal shop press.

But I want to try and get a little more creative and use a bell crank to up the ratio. I'll see what I can come up with. plus, I down want to buy two jacks. This is "Low-cost" right...?


Updated picture.

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Plans: Single Rotor turbo sub 1000lb machine!

ok, that design makes more sense for what you initially described.

I was picturing a bend brake, but adding a jack to be able to do bigger stock.

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Tucker

I built the SWAG press brake kit (heavy duty finger brake model). It is sized to fit a harbor freight 20 ton shop press. It will bend 3/8" plate, that said I am adding a narrower bed insert to accommodate thinner material in the 0.40 to .125 " range. I modified it slightly, because I over stressed my harbor freight press (before getting this kit), and built a new press with more capability but similar (but not the same) dimensions. You need a hydraulic press and to weld up the kit, but all the parts are supplied as well as instructions. I think the bed is 19 1/2"wide. The kits can be viewed at: http://www.swagoffroad.com/20-TON-Press ... _p_40.html
I liked the product.

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Thinking is the greatest leverage on effort
Great workmanship will not turn a bad idea into something good
Poor workmanship can ruin a great idea
R1 single seat track car, in progress
Maxima VQ35 mid-engine 2 seater track car, on hold

I've seen those. And they look cool. But I enjoy the design process and building from my design. Which is what brought me to Locost in the first place.

I'm going to stick with the standard jack in the center. After drawing up a few things, it's just not worth the effort to over complicate something that is so basic. I would also need a real ram instead of a jack. Which ups the cost significantly.

I'll post design pics and update as i build it.

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Plans: Single Rotor turbo sub 1000lb machine!

Updated design using two HF compact 20 Tony bottle jacks. These are the regular ones you have to jack by hand. I didn't use the air actuated ones because they were quite a bit larger. I want this to be as compact as possible.

Still needs work. But I would say it's 90% complete. I'm hoping to actually start cutting and welding within a few weeks on this.

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Plans: Single Rotor turbo sub 1000lb machine!

+1 on the SwagOffRoad unit. I have this and love it!

I have designed more tools than i can ever build in my life time. This is one area where unless you have the spare cash, easy access to the right materials and the spare time, you would be better off finding something that will work out of the box.

But i don't want to be discouraging of your desires, So on that note one concern about your last model. Your duel jack design will be very difficult to regulate even pressing. You can plumb the jacks to a single hand pump so the work on a parallel circuit and use valves at each to balance the pressure if you really need all of that pressing power. One 20ton bottle jack can support some really heavy bends. I mean you would be looking at heavy equipment territory. well above and beyond locost.

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-STu

There is no shame in defeat, so long as the spirit is unconquered

My Build Log

Since these jacks are the basic hand pump style, not air actuated. It will have one handle. Basically a large U to pump both at the same time.

I went with 2 jacks for a few reasons. One was I would rather have excess power than not enough. These are cheap HF bottle jacks. I would rather not work them to full capacity.

Another reason is spreading the stress across the points that will see force. Especially the top. Instead of the jack pushing in the direct center (weakest point) it's spread across a larger area. In hopes that I will not bend the top C channels when forming thicker material. Same goes for the base mount of the bottle jacks so I does not put excess force on the center of the dye.


Still a work in progress. I have started to collect material now for this. I have the bottle jacks and the V base.

I plan to make a few different form bases and dyes to create different radius as needed. But these will be done on an as-needed basis.

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Plans: Single Rotor turbo sub 1000lb machine!

You're going to want a taller I beam up top. IIRC - Stiffness goes up exponentially with web height.

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Too much week, not enough weekend.

OOPS I did it again
http://www.locostusa.com/forums/viewtopic.php?f=35&t=17496

Blood Sweat and Beers
http://www.locostusa.com/forums/viewtopic.php?f=35&t=15216

It's not an I-beam. It's two C-channels welded together. I'm debating on welding in stiffeners to these. That might come after I use it and I see some bending going on during use.

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Plans: Single Rotor turbo sub 1000lb machine!

Back to Back C's become an I in that configuration.
Adding stiffeners increases web thickness and has a much smaller impact on stiffness than making them taller.

Instead of 1x3 C's , use 1x4 C's or even 1x6 C's back to back. You'll spend less money at the steel yard and have a stronger brake.

I buy all my steel at a local recycling center. Last stuff I bought was 42 cents /lb. Same stuff from online metal was more than 4X the recycling price

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Too much week, not enough weekend.

OOPS I did it again
http://www.locostusa.com/forums/viewtopic.php?f=35&t=17496

Blood Sweat and Beers
http://www.locostusa.com/forums/viewtopic.php?f=35&t=15216

Is the finger support rectangle tube stock? I would recommend getting some heavy bar stock and sandwiching like so and welding one leaf on to the center bar.

The fingers can then be bolted into place.



This web page is great for figuring the tonnage you will need to bend a variety of steel thicknesses.

http://www.americanmachinetools.com/pressure_table.htm

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-STu

There is no shame in defeat, so long as the spirit is unconquered

My Build Log

I'll post a picture later, but there is a piece that holds the leaf/dye that is very similar to your picture. The 1x3 rectangular tube is really there just to be a guide. You can kind of see it if you look closely. There are nylon bushings that will guide the 1x3 along the .750 diameter rods. The "leaf holder" is welded to the 1x3. And the leafs can be unfolded and swapped out.

I have been thinking about removing the 1x3 and just making the "leaf holder" longer and adding guide holes to it. Minimal parts is always a goal for me.

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Plans: Single Rotor turbo sub 1000lb machine!