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Brake Backgauge Multiple Bends, Inconsistent Results

j c

Aluminum
Joined
Dec 20, 2013
Location
Queens
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?
 

Bondo

Hot Rolled
Joined
May 14, 2011
Location
Bridgeton NJ
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
 

j c

Aluminum
Joined
Dec 20, 2013
Location
Queens
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.
 

j c

Aluminum
Joined
Dec 20, 2013
Location
Queens
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.
 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
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 ?
 

Strostkovy

Stainless
Joined
Oct 29, 2017
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.
 

Bondo

Hot Rolled
Joined
May 14, 2011
Location
Bridgeton NJ
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
 

Don_S

Plastic
Joined
Feb 2, 2019
Location
SW IA USA
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.
 

Portable Welder

Cast Iron
Joined
Jan 9, 2015
Location
Milan, MI
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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