Homebuilt Press Brake

[Ver Steeg]

Hey Anders,
I designed a homebuilt press brake for my brother in law before I built the one I have, his uses (1) 20 ton hydraulic jack. I don't know if 20 tons is overkill but thats the jack he bought. The press had to have a large upper die assembly but he was able to do some simple stamping on it by making a die set. He is making a stainless frame for a Delorian (sp?). I will look and see if I still have drawings.
Ricky and Jeffery,
I live in Kennewick, which is located near the Hanford works project in Richland Wa. Ya, you are correct this site is very addicting, just one more thing to add to my already too many interests.
The only way I know how to bring pics to the forum is by putting them in my album so I will have to refere you to that.

[anders nørgaard]

Hi Lynn,

Thanks for starting this thread!
Gene Olson posted a great tutorial on how to attach images to a post the easy way. You'll have to change your options in the UserCP (Control Panel).
Here's a link to Gene's post.
If you can't work it out, send me a PM and I'll try to guide you!

http://www.metalmeet.com/forum/showthread.php?t=2613

http://smileys.smileycentral.com/cat/26/26_23_1.gif

[Ver Steeg]

Hey Anders,
Thought I would try the picture thing. This is the latest project I used the press brake on. Don't get confused it's a full sized model, for display only.
http://www.metalmeet.com/photopost/data/500/medium/DSC01409_640_x_480.jpghttp://www.metalmeet.com/photopost/data/500/medium/Car_in_museum2_640_x_480.jpg

[anders nørgaard]

Hey Lynn,

You're learning REAL FAST.

Great stuff you're making.

Keep it coming!
http://smileys.smileycentral.com/cat/26/26_23_1.gif

[Gene_Olson]

http://www.metalmeet.com/photopost/data/500/medium/DSC00535_640_x480.jpg
http://www.metalmeet.com/photopost/data/500/medium/DSC00534_640x480.jpg

Okay,
so here si the press he's talking about.

That is a nice looking unit Lynn.

G.

[anders nørgaard]

Hi Gene,

Quote:

Okay,
so here si the press he's talking about.

That is a nice looking unit Lynn.

G.

I see, you too are suffering from the common "right hand finger faster than the left hadn"

SORRY couldn't resist.
http://smileys.smileycentral.com/cat/26/26_23_1.gifhttp://smileys.smileycentral.com/cat/6/6_18_3.gif

[kenklose]

What are those doohickey's with the chains attached to them called? How do they work? If I had to venture a guess I would say that that the sprockets turned a worm connected to a gear and the center of that gear was basically a nut that raised and lowered the long screws I see protruding from the top.

[anders nørgaard]

Hi Ken,

What are those doohickey's with the chains attached to them called? How do they work? If I had to venture a guess I would say that that the sprockets turned a worm connected to a gear and the center of that gear was basically a nut that raised and lowered the long screws I see protruding from the top.

Lynn calls them screw-jacks (that's what we call them in Denmark too)
You're absolutely right about your guess on how they work!

The gears and chain are used to synchronize the three jacks.

http://smileys.smileycentral.com/cat/26/26_23_1.gif

[Boogiemanz1]

I'm wondering if a person could gang hydraulic jacks together with one pump and achieve that, or I guess short hydraulic cylinders would work for sure.......john

[anders nørgaard]

Hey John Buddy,

I've been wondering exact the same thing!
Remove the bleed screws from the hydraulic jack. Insert some sort of fitting, that allows ton conect 2 or more jacks.
Use an electric motor, a powersteering pump (can provide a pressure of at least 130 bars... sorry 1850 psi) and then we just need a control valve.
YES, I think it is possible!
http://smileys.smileycentral.com/cat/26/26_23_1.gif

[Gene_Olson]

john,

the problem with that is that it pushes hardest where there is least resisitance.
If you load is centered and the top beam is stiff, it will work ok, but if you put your part in one end the other end will come down first, that can cause the thing to bend unevenly, jam or even break. The same sort of thing happened with scenery wagons in the theater when we put hydraulics under them.
The light end moves first.

G.

[Boogiemanz1]

Thanks Gene! I was still thinking "build" and hadn't gottten to "use" yet.......

The mechanical jacks are perfect then,as they move the same distance each, despite the resistance. That is really a nice setup The chains give it a character different from most breaks.....I like it

The hydraulic could still be used if you used a separate valve for each cylinder and a bleed off line for each. Of course you would need to position your work accordingly, but the screw jacks look to be the best....and easiest..........john

[bobadame]

The nice thing about this mechanical system is that the guides only have to locate the top bolster in one plane, front to back. With a hydraulic system using more than one cylinder, there needs to be a flow divider valve to split the flow evenly between the cylinders. These valves aren't accurate enough to rely on as guides for the top die holder. There would still have to be heavy guides to keep things square side to side. Also this mechanical system gives you micrometer accuracy so you can sneak up on the exact angle you're trying to get and make repeatable bends. Really neat design.

[toolmanMike]

With a hydraulic system using more than one cylinder, there needs to be a flow divider valve to split the flow evenly between the cylinders. These valves aren't accurate enough to rely on as guides for the top die holder. There would still have to be heavy guides to keep things square side to side.

Correct. Any attempt to build a hydraulic bender that's much wider than the base of a single hydraulic jack is going to have problems without the addition of some kind of mechanical gizmo to synchronize the movement of the two ends of the moving beam.

Using a rack and pinion synchronizer where both pinions are on the same shaft might work.

The dual screw-jack idea is what's used on commercial machines. It's the simplest solution.

Mike

[r_barber]

The presses here where i work have 2 cylinders. they are huge and have huge cylinders but the concept is still the same. 10 ft across and has about a 10" cylinder on each end of the ram. The big mechanical ones have a flywheel and eccentric so you are forced each time stomp the pedal ,to make a full stroke of the ram. (cant air form) but with the hydraulic ones you can only move the ram as much as you want or as little as you want.

As long as you are bottoming the die i cannot imagine that two cylinders would not work no matter how synced they were. They are still going to end up bottoming the punch in the die. Air forming would be a different story.

Ricky

[hardtailjohn]

Another solution I've seen used is to use the hydraulic cylinder to power a bellcrank system. That seems to work very well and each bellcrank can have a fine adjustment on it, to keep things aligned the way you want them to be. Sometimes it's advantageous to have one end travel a bit further than the other, as in making a "trough" or spout.
A good example of the bellcrank system is at http://www.grkeck.com/Pages/keckpressbrake.html
John H.

[Ver Steeg]

Below is a sketch of how I designed a single cylinder press for my brther-in-law. This works and he used it to build a stainless steel frame for his
Delorean. You do have to make sure your work is centered because you cannot rely on the guide rods to keep the top puch assenbly straight under load, only on retract. We made the lower cross arm assembly pinned so that you could lower it and insert a round punch in the top and use it like a standard press, it goes up and down via pulleys and a hand cable winch. He used it to make some some pretty cool panel by making a die set to stamp a couple parts out of stainless no less. I was never satified with the design so I built the one using screw jacks to keep things true. Tonage is hard to achieve with screw jacks and they are very expensive when new. I like the bellcrank system that (insert name) linked us to, thats the way I would build on if I did it again.
http://www.metalmeet.com/photopost/data/500/Press_sketch.jpg

[Oldtin]

The ram tilt can be controlled with a couple of roller chains and a pair of double sprockets/rollers. With an adjustable clevis at the one end of each chain the ram tilt could be zero'd or adjusted to suit conical forming. I have seen this configuration in drafting straight edges, tube benders, and drive on truck hoists. It could be done with cables but I would place more trust in chains.

The Cincinanti 175 ton press brake that I used to operate had programmable ram tilt with two large hyd. cylinders, but I wouldn't venture a guess as to how it was hyd. distribution was controlled.

Les Edmundson

[Ver Steeg]

Very cool, that would work for a single point loaded press.

[Gonejunking]

After reading this thread, I walked out into the shop to look at the brake's we have. The first one, has 2 hyd cylinders, it is rated at 90 tons, bed is 10 feet long. The upper tool holder rides on ways shaped like a "T". One on each end, about 1.5" thick, by 4" wide, with at least 12" of contact. This one is computer controlled, and looking at the control panel, it should be able to do anything, including tying my shoes!


Another brake we have is a little Di-Arco. This is the one I want to take home. It takes up to 52" of tooling, is about 6 feet tall, 5 feet wide, and 4 feet deep. It's powered by a hyd motor, not a cylinder! The upper tool holder rides on 1.5" rods, has adjusters on each end, so you can tilt the punch. The adjusters, look like conneting rods from an engine. the big end is around an eccentric on a shaft that goes side to side, to connect with the one on the other side. In the middle of the shaft is the hyd motor. The motor can turn the shaft either direction, so you can back up, if you need to!
I tried to cut and paste a picture, but it didn't work. So I'll try and get Anders to help me.

[Peter Miles]

Since this thread has introduced a number of different actuation mechanisms for press brakes, here's another one, although it certainly doesn't qualify as a $500.00 tool. But the concepts may be applicable to something homegrown.

http://www.metalmeet.com/photopost/data/3693/Over-Centering_Press_Brake_1_2_.JPG

And for a rear view:
http://www.metalmeet.com/photopost/data/3693/Over-Centering_Press_Brake_2_3_.JPG

I don't know what would be the correct technical description for this articulation/activation mechanism - perhaps a multi-link, over-centering parallelogram?

[Gene_Olson]

It's a toggle press, like the pullmax but with multiple links.
That's some cylinder there . . . :-)


g.

[Gene Newcomb]

Why do you think someone would bother to do a break like that? I see no great mechanical advantage and it doesn't fit the KISS principle.
I haven't followed this thread too closely but I'll mention it anyway, I saw a small break at a machine show (IMTS in Chi) a few years back with two large air cylinders lever to the beam of the break.
It was about 2-3' wide, the cylinders were 4-5" round and probably a 2-3' lever w/ 6" on the other side of the lever point. I don't have time to figure it but with 100psi air you could get a few tons out of it.
I've thought about using it for a shop built press but decided against it due to safety concerns, too fast.
Gene

[Gene_Olson]

Gene there is a huge mechanical advantage near the end of the stroke.

[Boogiemanz1]

Hi Gene. Its actually the same principle as vice grips use. You don't have much power until the bottom of the stroke.

Someone built a hand operated louver press with a toggle mechanism last year or before. When Richard K explained the pricipal to me I was amazed...........john

BTW, Our pictures from Edmond got lost in the site change-over. I'm trying to get them reposted..........john

[Doug98105]

Guys,

Regarding the force curve for a toggle press.....

Here's one for my air operated toggle press. The total stroke of the press is 3/4".

Ram Force

Distance From
Bottom Of Stroke
.500 945 lbs.
.250 1383 lbs.
.125 1979 lbs.
.0625 2782 lbs.
.030 3970 lbs.
.020 4935 lbs.

As you can see in the .010" distance from .030" to .020" it develops a 1000 pounds more force. But in the .125" distance from .250" to .125" it only developed 600 pounds added force. It's easy to see this type mechanism may not be the best for general pressing operations since the max developed force only occurs very near the bottom of the stroke.

Depending on length of linkage arms, etc other toggle presses will have different force/distance curves, but it's apparent they're best in short stroke pressing operations.

Doug

[Gene_Olson]

From the looks of the one illustrated the high pressure end of the curve is all in the tool makes contact zone. The rest of it is in the open real wide to get an odd part in part of the stroke.

G.

[Gene Newcomb]

Gene,
Maybe I would have figured that out on my own after another cup of coffee. That's brilliant. Maybe I could have used the same principle on a louver press but the flex in my frame might have negated the advantage. I just listed a hydraulic last night (search Ebay: louver press).
It works great but it does flex, dang near 1/2" on 16 ga and 1/4 on 18 but what the heck it goes through. With Doug's calculations it probably would not cut.
Anyhow after my last listing with the Acme screw crank I found that most my inquiries were for hydraulic or just the dies. I've cut a C frame from 3/8 plate on the plasma for Mod 3.
John,
I'ld like to see the pics. I also wanted to mention that I am about done on my teardrop trailer that I told you about. I'll post some pics @ http://www.mikenchell.com/forums/ when I get done. I was thinking that a stylized motorcycle trailer for you would be an excellant MM project.
See you,
Gene N

[Boogiemanz1]

Gene, let me know when the photos are ready, I'd like to see them. You need to attend MetalMeet this year and give that teardrop a trial run!

I have the motorcycle teardrop all drawn up, but I already have enough projects to last me the rest of my life.....john

[7018]

That would seem like a lot of extra work for the home shop.I think that a brake built with 2 Hdy.cylinders would work just fine.I do like the concept of the one pictured..

[tdoty]

Actually, I don't think making a toggle linkage like that would be too much work for a home shop. Doesn't mean I'm likely to do it, but it really shouldn't be too hard - just scale it back a bit :lol: .

For the "screw jack" system, I am tossing around a couple of ideas. Would automotive jacks work for this? Maybe the screw type "bottle" jacks that Ford used to include with their trucks? Maybe a couple of scissor jacks?

Biggest question would be how to keep from burning up a motor when the press bottomed out. Hand cranking the whole system doesn't sound like a whole lot of fun.

In this particular case, I'm looking to make the most useful tool to fit in a small space ............ something that could be stored against the wall when not in use. It seems a press brake would take up less space than a box and pan. I have more space now, but there's a lot more stuff in it!

Tim D.

[Peter Miles]

At the beginning of this thread Lyn Ver Steeg posted the following two pictures of a very clever press that he made :

http://www.metalmeet.com/photopost/data/500/medium/DSC00535_640_x480.jpg

http://www.metalmeet.com/photopost/data/500/medium/DSC00534_640x480.jpg

If anyone wants to build a scaled-up version of this (not that I would ever suggest that bigger is better), the following might help you get started:

http://www.metalmeet.com/photopost/data/3694/Large_Gear_Jack_2_.jpg
OK, so it is another jack and it looks like it is fairly stout.

This is in a current eBay auction by Pacific Industrial in Seattle.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7579258897

According to the text of the ad:

The base is 24" wide, 1-1/2" thick steel. The top is 14" in diameter. It has a 1" input shaft geared down 20:1 to the main drive shaft, which also has an output flange on the opposite side (presumably for attaching to a second jack for balanced lifting).

Joyce # 08640833
Input Shaft: 1", Geared 20:1
Main Shaft: 3-1/2", 6" Output Flange
Base: 24" x 20-3/4" x 1-1/2" Thick
Top: 14" Diameter, Six 1-7/8" Holes
Min Height: 18" (estimated)
Max Height: 28" (estimated)
Weight: 1200 lbs



Yes, that is one thousand, two hundred pounds for a single jack.

They have 3 of them available. Starting bid $199.95, no bids yet. That is only $0.16 per pound!

It isn't a project that I need, but I bet that one could make a hell of a press with the 3 of them. At 3600 pounds just for the jacks though, you would certainly need a lot of heavy structural steel for a press that would do justice to them.

You'd be the only person on your block with a press like that!

Maybe it would be a good Bugly project.

[Mike Rouse]

I built one for my 6 to press.
Check it out at my web site http://rousecustomfabrication.com
Mike Rouse

[Avalonjr]

Biggest question would be how to keep from burning up a motor when the press bottomed out. Hand cranking the whole system doesn't sound like a whole lot of fun.
Tim D.

Tim,
Here are some suggestions to keep that motor from burning out:

1. Wire in a current sensor with a limit trip to shut off the motor.

2. If you are using a VFD, this could be accomplished with a few minutes of programing in the VFD. No sensor would be required with the VFD since they are built in....

3. Wire up the motor through an IEC motor starter which has integral thermal breakers. These can be set with a screwdriver for any trip current.

The idea is the same for each suggestion. You reach a predetermined torque, which indicates that you are bottomed out, the sensor opens the circuit cutting off the power supply to the motor.

Taking this one step further, you could wire a second starter off of the contacts of the first to automatically engage when the first trips. The second starter would be wired to reverse the motor. This would give you an automatic return action like a log splitter.