Good day all; been a busy summer and haven't had a chance to post much or work on the Bearhawk. I have been working through ribs at a snail's pace... I'm up to five that I consider airworthy, but another seven that are going in the scrap pile. I was at 3 and 7, so perhaps I'm turning a corner... I was worried I was going to end up making three planes and keeping one. I have a few questions on what I'm considering to be "airworthy" ribs, but I'll save those for later.
Right now, my question is about the nose ribs. Four of those seven rejects are nose ribs, and I have yet to get one right. The problem seems to occur when I bend the outer flange around the formblock. I get a "crease" with a bend radius that is too extreme. It's not the radius on the formblock - that's pretty generous - it looks like somehow I'm not able to set the radius while hammering the forward part of the flange. See the pictures attached to the message. I thought perhaps that my relief hole wasn't big enough in my first two, so I made it larger, but that didn't seem to make much difference.
I'm about to cut another set of blanks from a 4x4' sheet of 2024 T3 0.025 (I'm starting small until I get my process worked out), which includes another 4 nose rib blanks. I'm going to try a much tighter clamp right by the leading edge of the flange on the formblocks as I'm hammering, and may try to use the nose of my plastic mallet to set the radius (see last image attached - the rib there in the formblock is a center rib, and I've been using the plastic mallet to set the radius, and finishing with the deadblow mallet).
Any thoughts on what else I should try? I don't really like to use the plastic mallet much, as it's a little too hard and I don't want to work-harden the metal too much. That said, it seems to do the trick on my last three center ribs for setting the radius.
Many thanks for reading!
Right now, my question is about the nose ribs. Four of those seven rejects are nose ribs, and I have yet to get one right. The problem seems to occur when I bend the outer flange around the formblock. I get a "crease" with a bend radius that is too extreme. It's not the radius on the formblock - that's pretty generous - it looks like somehow I'm not able to set the radius while hammering the forward part of the flange. See the pictures attached to the message. I thought perhaps that my relief hole wasn't big enough in my first two, so I made it larger, but that didn't seem to make much difference.
I'm about to cut another set of blanks from a 4x4' sheet of 2024 T3 0.025 (I'm starting small until I get my process worked out), which includes another 4 nose rib blanks. I'm going to try a much tighter clamp right by the leading edge of the flange on the formblocks as I'm hammering, and may try to use the nose of my plastic mallet to set the radius (see last image attached - the rib there in the formblock is a center rib, and I've been using the plastic mallet to set the radius, and finishing with the deadblow mallet).
Any thoughts on what else I should try? I don't really like to use the plastic mallet much, as it's a little too hard and I don't want to work-harden the metal too much. That said, it seems to do the trick on my last three center ribs for setting the radius.
Many thanks for reading!
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