bend allowance

[StokedMotorSport]

working with 1/8'' aluminium and a 90* break looking on how much extra to cut
thanks in advance

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[Becerra]

working with 1/8'' aluminium and a 90* break looking on how much extra to cut
thanks in advance

Check this page out
http://aviationandaccessories.tpub.c...3-0106_318.htm
hope it helps

[scottm]

Metal stretches when it bends, so you make it shorter by the 'bend deduction'. For .125 5052 alum with an inside radius of .030, you deduct .175" in the flat pattern.

[Becerra]

You can use either calculation method. Bend allowance or bend deduction depends on how and what your measuring and doing.

[standfast]

It depends on what you are using to bend it. On a press brake with .031R punch and a .560 V-die I have a bend deduction of .197" on .125" 5052. Now if I change that .560 V-die out for a rolla v-die I have a bend deduction of .191". If I use a folding brake with an .031"R it it will be at .184".

Different tools will produce different results. For high accuracy parts you need to take a test piece and bend an exact 90 on a piece that your pre-measured the flat length length of. Then measure with your calipers the length of each leg and add them together. The sum of the 2 legs minus the length measured when flat is your bend deduction. I have a monster of a list of all different materials that I use here at work and bend deductions recorded using different tools over years of precision sheet metal fab. Having that info is critical to designing and building precise sheet metal parts.

[mfs]

yea just take a scrap piece and mark it like 1" and bend it and measure how much longer it got -1".