graphical reference showing parts a press brake can make a finger brake cannot
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  1. #1
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    Default graphical reference showing parts a press brake can make a finger brake cannot

    I'm trying to educate some folks on how to make designs that can be fabricated using foot shears, finger brakes, and similar. As part of this I'm looking for a chart, table, or the like that shows parts you could make on a press brake but couldn't make on a finger brake, ideally with notes about why.

    Or, a list of features (tabs sticking out of panels, flanges swinging opposite ways from a single edge) that aren't generally feasible on a finger (box-and-pan) brake.

    [I have this in my head, probably many of you do to - but I'd like some reference to point folks at rather than writing and drawing for a day to explain it.]

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    Not making this one with a finger brake.

    18-bkt-fold.jpg

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    Here is another one. The 3 upwards flanges get folded down making a drawer cabinet with tray top. The open front is already folded down. I folded the 2 opposite sides down and when I folded the back down bad things happened. My punch had horns at the ends and the whole assembly got trapped on the punch. 7 at night and shut down and go home. Left it hanging on the machine because my right arm was in a sling from shoulder surgery. Next day I had a helper with 2 hands and I remover the center pieces of sectional punch and slid the horns free.
    3-bent.jpg
    Another one. Stainless steel joist hanger. Straight punch for all bends. 3 strokes. 2 side flanges were first bend from flat. The deep bends were done by using 2 horn punches pointed together. Control gave a collision alarm but the first long flange poked through the opening from the horns.
    20200616_153703.jpg

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    Quote Originally Posted by Scruffy887 View Post
    Here is another one. The 3 upwards flanges get folded down making a drawer cabinet with tray top. The open front is already folded down. I folded the 2 opposite sides down and when I folded the back down bad things happened. My punch had horns at the ends and the whole assembly got trapped on the punch. 7 at night and shut down and go home. Left it hanging on the machine because my right arm was in a sling from shoulder surgery. Next day I had a helper with 2 hands and I remover the center pieces of sectional punch and slid the horns free.
    3-bent.jpg
    Another one. Stainless steel joist hanger. Straight punch for all bends. 3 strokes. 2 side flanges were first bend from flat. The deep bends were done by using 2 horn punches pointed together. Control gave a collision alarm but the first long flange poked through the opening from the horns.
    20200616_153703.jpg
    Guy who makes his own joist hangers, brings a tear to my eye

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    Scurffy887 - great examples - if you don't object I'll copy those photos into a document I'm making about what can, and cannot, be done on a box-and-pan/finger brake, as opposed to a press brake.

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    Hoist hanger isn’t especially easy to make on a press brake with conventional tooling either.

    A skilled operator won’t have issues doing much with either.

    Where a press brake excels is thicker material. You can fold a 4” deep pan out of 1/2” material on a comparatively small machine.

    At the same time, you have to remember that some of the tonnage on a press brake is used lifting the plate to a 45 deg angle.


    Sent from my iPhone using Tapatalk

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    Quote Originally Posted by gustafson View Post
    Guy who makes his own joist hangers, brings a tear to my eye
    Kinda common amongst us that can weld.....

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    Quote Originally Posted by bryan_machine View Post
    Scurffy887 - great examples - if you don't object I'll copy those photos into a document I'm making about what can, and cannot, be done on a box-and-pan/finger brake, as opposed to a press brake.
    No problem. I'll post some more.
    This is a stainless steel roll away I just finished yesterday. Many of the parts "could" be formed with a B&P brake, but most of the parts with deep flanges on opposite edges(drawers) would be stuck in the brake when final flange was formed. Yesterday I brought it home and applied the mahogany drawer fronts, attached the pulls. Pulls are 13g stainless formed with bullnose punch and roll die.
    20200712_160642.jpg20200712_174442.jpg

    .120 stainless foundation bracket for my back steps. Most people bolt a ledger directly to the rim joist. Not a fan of that as it can trap water leading to rot.
    20200614_150050.jpg

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    Another trick a press brake can do is to flatten the ends of tubing before they are pierced for bolt holes. This is common for bolt-on braces.

    The punches of course are flat-faced rather than v-shaped.

    Press brakes have a lot of other nifty tricks for working on other than sheet metal. I'll try to list some more if my rusty old brain can recollect them from over forty years ago.

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    Scruffy,
    What did you use for slides, and where did you buy them? A couple of detail pictures of a drawer would be nice. I've made drawers on my b&p, but I weld the front and back on.

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    Quote Originally Posted by gbent View Post
    Scruffy,
    What did you use for slides, and where did you buy them? A couple of detail pictures of a drawer would be nice. I've made drawers on my b&p, but I weld the front and back on.
    All but one of the slides are Accuride 100# full extension with soft closing feature. The big top drawer has an Accuride 500# and also a 100# soft close. The 500# slides are rock solid and smooth, but do not come with the soft close feature. https://www.hafele.com/us/en/ Really need that so the drawers do not open when moving the chest. This roll away is all 16g 304 except drawer bodies, drawer backs. Those parts are 16g galvy to save $. 3 piece drawer spot welded together. What you can't really see in the pic are locating tabs that are laser cut to precisely locate the front and back for spot welding. Tabs include a slot where the drawer side tab must poke through to keep it square. The SS drawer front protects the top of the wood face and looks good too. I have made 1 piece drawers but am limited to 4-5" depth because of punch length, and at that I need to move the punch holders for clearance.
    This is the second roll away I have made. First one took about 150 hours, but most of that time was R&D, and making a few parts over. The carcass of this one was maybe 8-10 hours to cut, bend, assemble. Drawers 16 hours, wood 3 hours. The most time consuming part of the Stainless work is positioning the carcass for spot/TIG welding during assembly, and getting the brushed/burnished finish. But every time I make a cabinet things go faster.
    20200419_165345.jpg

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    Quote Originally Posted by Scruffy887 View Post
    No problem. I'll post some more.
    This is a stainless steel roll away I just finished yesterday. Many of the parts "could" be formed with a B&P brake, but most of the parts with deep flanges on opposite edges(drawers) would be stuck in the brake when final flange was formed. Yesterday I brought it home and applied the mahogany drawer fronts, attached the pulls. Pulls are 13g stainless formed with bullnose punch and roll die.
    20200712_160642.jpg20200712_174442.jpg
    That rollaway is a seriously classy piece!

    It's surprisingly easy to come up with a combination of bends that can't be done on a box and pan brake. I have a client that seems to specialize in designing parts that fall into this category. Because the majority of the parts are pretty small, I got a Hossfeld bender with flat bar tooling which is a very useful piece of equipment for duplicating things that can't easily be done without a press brake and a large quantity of tooling. I would do Scruffy's joist hanger by bending the long flanges in the box and pan first (or my small press brake for stainless) then the short bends on the Hossfeld.

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    Who says you can do more on a press brake ???
    On a decent pan brakes can do high narrow U shapes as a example
    Except the first picture perhaps all the other examples can be done on a pan brake too
    One can also make big radiuses in a single go on a panbrake
    In fact I think a pan brake is more versatile as a press brake with thin sheetmetal
    Take a look at afew examples from the website of RAS
    Furniture/Shop fitting/Laboratory
    Also handling is easier as only 1 part moves while bending
    So easier to automate

    Peter

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    Quote Originally Posted by digger doug View Post
    Kinda common amongst us that can weld.....
    No welding needed

    I know why he did it, so someone can take his deck apart in 50 years and say, WTF!

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    Here is a quick list of things I can't do/have trouble doing with my box and pan brake.

    anything with a reverse bend
    places where I only want a bend across part of a sheet or an internal bend
    deep u bends
    folding the second side of a square corner. The overbend to account for the springback crumples the adjacent side

    Where the box and pan does well:

    fast set up for one-off "make it like this" parts
    making a bend near holes or other features that weaken the part where those features would be inside the vee of a press brake
    bending short legs on large sheets
    bends on any sheet large enough to be flimsy

    Its easy to find books on working/tooling a press brake. I've yet to find any book or pamphlet on working with a leaf/box and pan brake.

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    Quote Originally Posted by gustafson View Post
    No welding needed

    I know why he did it, so someone can take his deck apart in 50 years and say, WTF!
    I only needed 14 hangers and bought them from H Desperate. But they have changed the design and the new style has an additional flange that covers the top of the ledger. Maybe ok for plywood decking (nailing the deck will bend a few nails), but this was our back steps and the deck was 1x12 Sapele Mahogany. Last board would get twisted or lumpy looking.

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    Good examples already but I'll add the cabinet drawers in my cabinets in the last post in this thread: Anyone ever use the Lista Knock Off's from Global Industrial? Look at the drawer parts in the PDF file.

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    Print a scale model of both a press brake and a finger brake.

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    More pics. Deep bend with second flange through a window. 20200714_154025.jpg20200714_154043.jpgNesting joist hangers.20200714_154133.jpg
    Good luck making this on a box and pan.20200714_164621.jpg
    Or this, but this part of a heavy duty base is 10 gauge. Not something you want to bend by hand. Part was rejected because the material has slightly inconsistent thickness and getting accurate air bend angles from end to end was a problem. I can correct that in the control, but this part had to by flipped over a lot and the compensation over corrected when flipped. I would need to compensate every single bend and also mike the next sheet before bending.
    20200714_175330.jpg

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