Brief update for any interested: Couple of hours head scratching and sketching out a basic design- following Allan's general layout. Gathering material from rack and container to stack it together and scratch my head some more then got on with it. The premise was 1] a job specific tool to do close together bends <5" on 1/4" X 7" material with 13" legs. 2] tooling had to be cheap and what was available from the rack or minimum purchases from remnants at the suppliers. 3] accurate repeatable dimensions.
No tool steel here, it's all A36 and A 500 1/4" X 2" X 2" Sq. tube. Drug out a piece of 3/4" X 2" bar, fixed it up to cut in the band saw and got a nice looking 10" long 90 degree included angle cut with 2 45 deg. slices. Couple of swats with a sanding disk and some draw filing with a mill bastard and a right nice looking upper die was ready. Two lengths of 3/8" X 1 1/2" Angle, toed down to form a "W" tacked up to a length of 1/2" X 5" bar and the bottom die was looking good. 90 deg. check on the bottom die showed more like a 93-95 deg. included angle but the reading I've been doing kept talking about the "8 times rule" and the dimension between the crown of the inverted angle was 2 1/8" so I'm figuring close enough. Everything stacked up and the Sq. tube gets tacked to the base, 20ton jack placed to get a good eyeball on locating the stationary top die, get it all tacked up, do some welding on the Sq. tube, don't put on the flat bar guides for the lower angle iron dies until I see if this thing is going to work. Can't wait any longer and slice a 2" wide piece of 16Ga. in the shear and bend it up. Too good to be true- no gauges or means to measure angle and spring back but yeah, perfect 90. Up a notch. Take a piece of 16Ga. X 6". Bend 2 90s 3" apart. great. This thing is going to work. It's not all the way welded out yet, but figure "go ahead. push it a little". 1/4" X 2" bar in and start cranking [yeah, it a manual 20 ton, I mentioned cheap right?] and immediately notice this little piece of 1/4" doesn't move as easily as the 16 guage. Stroke the upper die to the bottom of the lower angle die and it barely makes 90. I know the spring back is gonna fail this. It does. back in and hit it again. 2nd time makes a 90. I'd been reading about "coining" and air bending vs bottom bending. Figure this is what they're talking about. So decide to put it to a tougher test. Grab a 1/4" X 4" rem of flat bar, put some lay out lines on to start figuring radii take outs [always understood it to be 1/2 material thickness, not so much here] and get to cranking. Not so good. About the time the piece is bottomed out in the lower angle die and still only maybe 80 degrees, [did I mention this contraption isn't even all welded out? The lower angle iron dies are just well tacked] I start to hear sounds of begrudgement coming out of this inanimate object. Give it a crank and there's a click, click ,click. Another, and a little click, ping, ping. I don't like the sound of this at all. Anyone remember the movie "Das Boot"? When they had to dive deeper than the WWII subs hull was rated for? It was kind of like that with the image Stringer put in this thread about the guys face getting half chewed off when hydraulics met Immovable Object [not that my face couldn't use some rearrangement but I'd prefer maybe just a good dental plan or a shave]. Again, to get the 90 degree bend takes more than one bending attempt, sometimes 3 or 4. And the clicking/pinging of steel pushed to it's limits doesn't make for a relaxing work enviroment. The jack is maxed. When I release it I watch for what moves. The bottom 1/2" plate the tubes are mounted give a tiny bit and when maxed it looks as though the 1/2" plate for the bottom dies is giving some flex as well. Can't see light under a blade but it looks flexed. Don't want to get into having to bend these hot. The plan is to double up the 2, 1/2" plates with a doublers and some slot welds and see if that doesn't give it the "overkill" recommended in the first place. Gotta say this though, properly built to withstand the required pressures the design will allow for very tight bends with no "back breaking". As it stands now it will do 2 1/2" between bends on light material with long side legs and it's worth continuing the experiment before biting the bullet and sending the job out to a proper machine shop. Had some fun today. Further reports as things progress. Thanks for the contributions so far. Allan- it's a great solution you've provided, I want to see this work. Also plan to try using 3/8" X 2" angle for the bottom die and increasing it's width. Thinking that will require less force but not sure what it will do for radii. However it resolves, I already have an inexpensive, lightweight, portable bender I can always throw on the truck. Think I'll wear the Goalie mask tomorrow in any case.
yojimbo, please, please, please, be careful! I have a "slight" idea of what you have described, but, pictures please.
I believe that you might be undersize on the components, particularly when you go to a 7" width of the 1/4". The "mobile" bottom die needs to be stiffened more than you have allowed for at this point. The upper die will likely require additional stiffening as well. WELD, WELD, WELD, before you do any additional testing. and be sure to stay well clear of the line of fire if anything lets go. In other words, not above or beneath it, nor to either side of it. Directly in front will pose the least threat to your health.
20 tons of jack force might be a little bit under what's required as well, but that's the least part of an issue of what you have described thus far. Again, be careful and use plenty of caution. Best regards, Allan
I know I am real late on post but very interested....I have built supports before to run cinncinati dies outside the ram and bed to do just such work....width and thickness of piece matter a lot to keep from cracking a $$$$ factory die. I have made a crap ton of homemade rigs to work with various ironworkers out of simple A36 steel and welded with S70 mig wire. Not just for bending sheet metal clips but 3/8 material too...... A friend of mine built an 8ft "home made" press for bending steel and it was impressive in the fact he could do 1/4 steel up to 4' and get a even 90. On lesser thicknesses it was wonder full and he cut out slots in the ram just for achieving parts like you describe. I hope you pull it off and it works fine.....always be super cautious the first few bends....after standing on it till a pump is screaming one or two times you know it is not gonna fail on you in a bad way.
2nd Update. Rebuilt in overkill mode. Switched out base plate to 3/4" X 5 X 20" and Uprights to 3" X 3" x 5/16" Sq. Tube. Upper stationary punch die is 1" X 3" X 10 1/2"" bar with 85 degree included angle. Lower moving female die is 2 1/2" X 2 1/2" X 3/8" Angle mounted on 3/4" X 5" X 10 1/4" flat bar which has 1 1/2" X 3/8" flat stock welded to outside of angle legs and extend outside to center of uprights to provide additional stiffness to angle and to act as guides for the lower moving die. Opening of lower moving angle die is 3 1/16". This wider opening allows for lower tonnage requirements but also increases radius of the bend which will still be within tolerance for this application- these brackets are going to be used for bracing the framing on some old balconies a contractor is rebuilding and way more than needed but the EOR wouldn't permit the use of Simpson brackets the contractor wanted to use.
After weld out started to test it. Up to 1/4" X 4 1/2" flat stock the unit works well and easily. Don't have any of the 1/4" X 7" flat bar the brackets will be made of so sheared a 7" length of the 1/4" X 4 1/2" flat stock and bent it. It bent with effort and sure enough having no radius the sheared end started cracking. Sheared and sanded a radius and the shears on another 7" length and bent it with no cracks. On that second 7" piece that had a radius sanded into it I noticed two things, 1] it seemed to bend with slightly less effort [something to do with the cracking or simply there might always be variations of structure/properties in steel even in the same piece of material?] 2] I bent it more slowly, taking 3-4 seconds between strokes as it approached 90 degrees, thereby possibly giving it some time to "adapt" itself? I do know the speed of the bend just as the speed of a piece in the section roller effect the outcome, so with some more playing around the "best" method may present itself.
There will be no problem with width on the bending- it's only restriction is the width of the upper punch die, so 3" inside and a 3 1/2" outside dimension with 13" legs is doable without back breaking and then flattening out the back bends. The narrowest I need is 4" X 13". No indication of undo stress, strain, give or the tweaking pings and creaks and unnerving sounds of impending disaster from first unit. Eyes wide open of course and wits around but I will be able to do the project even if slower and with more effort than originally planned for.
Allan: Thanks for the concept and sketch/plans you provided. You saved me a lot of head scratching and your design is effective.
Tommyjoking- You have given me a great idea in your post. After yesterdays fabrication of the unit and testing and realizing the results could be obtained but at the cost of substantial effort I went back to price the 12" brake press accessory for the 50514CM Scotsman Iron worker. At $1400 and not able to provide the narrowest bends I need [ about 50 of the total 106 ] for this I'm not sure it's worth it. But as suggested in your post: why not build a unit that will mount in the Iron worker and use the 50 tons of hydraulics available there for the wider 13' X 13" X 13" brackets? If there's clearance of those, which I am going out to measure this morning it will be back to the head scratching to come up with something that might work there.
After all only amateurs borrow. Professionals steal.
I'll get some pictures up when there's more time.
On an Ironworker because of the tight spaces around the shear table I usually built these dies to run off the punch end. Some Ironworkers have that dammable bolt on plate to the punch table with is usually insufficient support....so I would just make the bottom of the die self supporting strength wise and use those same bolt mounts...if they were deep enough and large enough. If not use side plates to go down the frame and drill out for through bolting....especially if I had to get very far outside the frame to clear. Where there is a will there is usually a way to make it go with what you have. Some have the angle shear located just right to accept a die that can extend past the frame in such a way to make a tight u bend. Gussets....heavy gussets for that scenario.
Hello again yojimbo, glad to hear of the "rebuild" to a more robust design. Also glad to hear that you are on your way to successful production on your project. Would definitely like to see some pictures.
As to possible speed increases in your design, an air-over-hydraulic unit, whether that be in the form of a porta-power or an air-over-hydraulic jack, that might be a reasonable answer. Stay safe and good luck on the project. Best regards, Allan
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