Shop Built Press Brake

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A friend and I have been kicking around the idea of building a press brake that is capable of bending 10 ga. steel sheet  48" wide.  I had seen the basic idea for this configuration of press brake somewhere a few years ago.  Here is my drawing of the proposed design: The construction is pretty simple and straight forward and we have the capabilities for that to be accomplished.We have one of the hydraulic pump packaged units that powers the popular car lifts.  It is capable of generating 1500 lbs. of pressure.  Using a 4" cylinder should net 18,850 of force at the upper end of the bellcrank.  The bellcrank has a 5 to 1 ratio so that should generate 94,248 lbs or 47.124 tons of lifting force on the lower plate.  Of course there will be losses along the way for friction and the weight of the lower plate , but I don't think that there would be much.According to a tonnage chart for press brake dies, a 48" wide  piece of 10 ga. being air bent using a V lower die that has an opening of 1-1/4" requires 7 tons per foot or 28 tons total.  If my math is correct it looks like what we want to accomplish is doable.The plates are 1/2" plate that measure 23" x 60" before the corner notches.  The ends are 6" channel that is 60" tall.  The feet are 2"x3" rectangular tube 24" long.  The 4 bellcranks are 1/2" plate and the end fittings for the links is 1/4" plate.  The cross links are 1/2" x 1-1/2" C.R. bar stock with the end fittings welded to form the clevises.  The lifting links are 1/2" x 2" C.R.   All of the pins (not shown in drawing) are 3/4" and the pivots for the bellcranks use turned pins of 1-1/4" with shoulders for the plates to face against.We priced the materials from our local metal supermarket (which isn't the best way to buy them) and it was a little under $700.00. We liked the redundancy of this design in the double set of linkage.  The vertical movement is designed for 2" of travel.  I'm sure that most commercial brakes have more than that, but we feel that should be enough for our purposes.  The holes in the lifting links are spaced 2" apart  allowing for 6" of change.We welcome any comments about the design or sizing from those with press brake experience.Last edited by George Barnes; 02-14-2012 at 12:01 PM.Reason: Paragraph breaksGeorge Barnes -  Tubular Dynamics
Reply:I have a 4 foot 30 ton press brake right outside my office. The plates on it are 1 3/8 thick.We do not push this machine very hard but what you are talking about would require shimming to eliminate crowning on my machine.1 1/4 inch die would give you a 3/16 inside bend radius which is fairly big, we normally use a 7/8 die so we get a 1/8 rad but that ups the tonnage quite a bit.I would suggest doubling up your plates with a 1/2 inch  spacer in between. The space will give a place to set the tongue that is on standard press brake tools. The design looks like how both of my press brakes work.
Reply:Their is a guy that sells plans for one that uses cat pins and bushings. I would not build somthing were you have to hit a moving target. Think about this the part you are holding on to is siting on somthing that is moving it will make it a nitemare. Make top come down. I started to build one till I found out how much presser it would take. But it would be great to have one.
Reply:I've been thinking of building something similar in the 100 ton range. Beserk on pirate4x4 is building one and has some great build photos. He's near the final assembly stage.http://www.pirate4x4.com/forum/showthread.php?t=1024437Here's a model I made that shows the motion... it's buried in the thread above. Note that the video is showing with gravity and without gravity (constraint) because I was working on the bushings and had some holes in my thought process. [ame]http://www.youtube.com/watch?v=G8XG7-dLK7Q[/ame]Last edited by forhire; 02-14-2012 at 04:42 PM.Reason: Added youtube link
Reply:Iroquois Iron Workers use the bell crank design in their brakes.How thick are your big upper and lower plates?  I was imagining that they need to be 1"+ and that would be a chunk of $$$.My name's not Jim....
Reply:Originally Posted by BoostinjdmIroquois Iron Workers use the bell crank design in their brakes.How thick are your big upper and lower plates?  I was imagining that they need to be 1"+ and that would be a chunk of $$$.
Reply:Some things I like about your design and others I don't but I can't tell you from actual experience whether your design is better than the one I've been playing with in my head for the last few years.   However I ran the numbers through beamboy to check the deflection of your design as stated and came up with .007" deflection in the middle using your 7tons per foot figure. While this doesn't seem like a lot it is enough to make for a curve in what you're breaking. I then ran the numbers with 1" thick and 1 1/2" thick plate using your sizes and it came out at around .004" and .0028" deflection.   But here's the kicker. By going with a 36" tall 1/2" plate instead of the 23" tall the numbers come out at .002" deflection. Thus the height of the plates is really the critical factor. That said I think I'd want something to keep the plate from trying to buckle sideways if going with 1/2". I'd at least want some flanges somewhere to stiffen it.   Here's some shots of one I threw together last week for bending heavy plate. In this case I was needing to bend 15" of 3/8" plate but while I was building I wanted to be able to go to 24" of 1/2" if needed. I ran the numbers and came up with to much flex in the top piece so I sandwiched the 1/2" x 6" with 1/2" x 5". I would of used taller pieces if I'd had them but that was all I had in stock at the time. I've also included shots of the finished pieces that came out of it. Attached ImagesMillermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:I'm kind of surprised at the lack of interest in this design for a press brake.  The construction seems pretty simple and straight forward to me.  I have to admit to going a little overboard when building tools as I like to get them as close to their commercial cousins as possible but staying in the home shop realm.This tool would undoubtedly see a lot more 16 ga. than 10 ga. and we could live with .007" of deflection in the middle quite happily.I found the build of the version of the Iroquois quite interesting but it struck me that it sure was a  lot of work and money.This is another one of those deals where logic gets thrown to the wind and you want to do something just because you want too.  If or when this project gets off of the ground, I'll post some pics.George Barnes -  Tubular Dynamics
Reply:Originally Posted by George BarnesI'm kind of surprised at the lack of interest in this design for a press brake.  The construction seems pretty simple and straight forward to me.  I have to admit to going a little overboard when building tools as I like to get them as close to their commercial cousins as possible but staying in the home shop realm.This tool would undoubtedly see a lot more 16 ga. than 10 ga. and we could live with .007" of deflection in the middle quite happily.I found the build of the version of the Iroquois quite interesting but it struck me that it sure was a  lot of work and money.This is another one of those deals where logic gets thrown to the wind and you want to do something just because you want too.  If or when this project gets off of the ground, I'll post some pics.
Reply:Originally Posted by Mick120Hey Irish,Did you use the bent flat bar template to fold to and, sneak up on the correct angle?I use a Handy Bend that Shopoutfitters in CO sell and, operate at the end of the ram travel, using the adjustable repeatable bend attachment to do repetitions.I've also built a bigger version similar to yours but, used 25mm tool steel for the blade.
Reply:Originally Posted by George BarnesI'm kind of surprised at the lack of interest in this design for a press brake.
Reply:Originally Posted by irish fixit Oh yeah. In case anybody is wondering the reason I used the hex for the bottom die is that it's 4140 and I have a bunch of it in 1 5/8" size. I thought it would be better than 1018 round. I'm not as sure of that now since I did have some trouble with galling where the plate slide over the sharp corner. I've done some grinding to round the corner but still need to do some more.
Reply:Originally Posted by forhireWayne, I bent a bunch of 4"x 0.375" 6161-T6 aluminum this week and had problems with galling. I used a slip sheet of gauge aluminum between the dies and the material. No marks.
Reply:Build it George!I'm still using my original Jig-A-Joint tubing notcher!Mike
Reply:Originally Posted by Mick120I must be spoilt with my old 60 ton girl.Long travel ram, has no problems going full travel....makes it easy for repeatable bends.Also some pics of the brake I built about 6 years ago....using channel prevented galling.I posted these a while back in another thread but, what the heck.
Reply:Originally Posted by Mick120Wow...I just looked at that thread on Pirate4X4, thanks for posting Forhire, giving me food for thought.