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Bend Radius

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  • Bend Radius

    Hello everyone, happily cutting rib blanks for what will someday be a 4-place BH model B! My thoughts are now turning to forming them, and I have question about the bend radius for the .032 rib flanges. From what I have read, a 1/16" round-off on the edges of the form block will make a sufficient radius for the .025 ribs, but will this work for the .032 ribs as well? Or should I cut another form block with a larger round-off, such as 1/8"?



  • #2
    If you have a copy of 43-13A or B that will have a chart for the bend radius. I think I used a roundover one size bigger than needed. Figured
    that would keep me away from cracks on the bend line. Did a die-pen test n several of them when I started -- no cracks found.
    I THINK I used a 1/8 radius bit for both thicknesses.

    PS- get a 43-13 if you don't have one-- lots of indispensable info in there..... At some point an inspector will be looking to see that everything conforms to whats in there.



    • 75Fox
      75Fox commented
      Editing a comment
      Thanks Tim...The radius chart in the 43-13 seems to conflict with what is written in the BH book regarding the .032 bends for 2024 T3. I'll experiment to see if there is any conflict with the rivet points with an 1/8" roundover bit. Barring any problems I'll just go with the 1/8".for both thicknesses.

  • #3
    This topic came up years ago, back in the Yahoo Group days. Bob's response then was that the 1/16" radius would be fine on the .032 ribs. I used a 3/32", and I don't see any problems with 1/8" (though I might ask Bob first if it were me), but you will be fine with 1/16".