Brake Backgauge Multiple Bends, Inconsistent Results
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  1. #1
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    Default Brake Backgauge Multiple Bends, Inconsistent Results

    I have a Atek press break with a manual backgauge. I set up a few stops on the backgauge to make a part, but I'm getting inconsistent results. The problem isn't the first or second bend, it's the third I think. I have 3 135 degree bends in a row. So by the 3rd bend the part is pretty floppy. It's .030" stainless. I just have a piece of tall steel angle for the stops. If I push the part up to it on the third bend, there is some variation depending on pressure. Are there any ways to make this more accurate? Is there a better backgauge design that I could use?

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    I have a 230 ton Cincinnati that is all manual. We manually measure all the bends and everything comes out perfectly "almost" every time.

    When using an angle stop, you have to remember that if you hit it high or low, it will change the dimension.

    You stated 3 120* bends in a row. It is very unreliable using a back gauge stop off of an existing bend, unless it is exactly 90* or more. So a 95* bend (overbent) will always have the same touch point.

    Sent from my SM-G960U using Tapatalk

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    Thanks that makes a lot of sense about the 90 degree, and the overbent being more accurate. Is there any other option for a backgauge design that could accommodate bent parts? Otherwise I may have to get a taller die and cut a hole in it.

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    I would need a picture of the part to give you a better description

    Sent from my SM-G960U using Tapatalk

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    j c Where abouts are you in NY just curious.

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    Can you change the order of bends to start in the middle and always gage off a flat edge?

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    Ok here are a couple images

    img_4795.jpgimg_4796.jpg

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    Hey DK, I'm in Queens. Are you upstate?

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    I realize now that gauging off the flat edge is really the most accurate way. I can't really do that since the part will hit the punch on the last two bends. There are 6 bends total, forming a C shape.

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    Quote Originally Posted by j c View Post
    Hey DK, I'm in Queens. Are you upstate?

    Yes, southern tier, Corning area.

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    Quote Originally Posted by j c View Post
    I realize now that gauging off the flat edge is really the most accurate way. I can't really do that since the part will hit the punch on the last two bends. There are 6 bends total, forming a C shape.
    How about a sketch or drawing of the completed part ?

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    If your six bends are from front to back 1,2,3,4,5,6 can you bend in the order 2,1,4,5,6,3 or 2,1,5,6,3,4?Then you have just one or two bends you can't directly gauge off of and will have to scribe. I personally leave tabs or holes in noncritical areas for the backgauge to hit, but that looks like not an option with your equipment.

    The laziest option is to bend in the above sequence, except you do a tiny bend at bend 3 (and possibly 4) just enough for the punch to make a mark to line up to after.

    Abusing the brake with tooling hanging off the side is also an option for eliminating interference.

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    Bends like that are best done on an apron brake. They are made to do things especially like this.

    To do this on your brake, you will have to just eye measure the third bend, which I am assuming is between the 2 bends in your 1st picture. By eyeing it, you will need to put a mark on it, then eye it up to the top die. It's not hard to do, just a pain. Or you will have to build a specialty gauge system just for it.



    Sent from my SM-G960U using Tapatalk

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    You could set up a couple of front gages a short one for bend 3 and a tall one for bend 6. Bend 3 would be against the flat edge opposite the first 2 bends and bend 6 would contact on the 90-degree face of the opposite bend.

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    Could you just fab up a multiple stop front gauge?

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    Double check that one sides not bending more than the other, the side of the sheet that is not bending enough is the side that will hit your back gage first throwing your piece out of square.


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