Tom Martin
Well Known Member
The left elevator skins have a close out tab that needs to be bent, one down the other up, to form a lapped joint. The plans call for the use of a piece of wood sandwiching the skin to a work bench. Then using another piece of wood to bend it down. I am sure this works but I present a simple alternative that is accurate and repeatable. I made a simple "brake" using some scrap angle.
I cut the short angle the same length as the tab to be bent. The "bed" angle, the angle that the tab bends around has the sharp edge filed off to give a nice radius. On the picture you can see how the bed angle has a round radius. I left the plastic on to limit any marking of the material during the process. Mark both sheets with a line as documented in the plans. Put a line on top and bottom of both sheets and then lay the sheets together to varify that the lines are in the exact same locations. Mark on the sheets which tab bends bends up. On the first sheet, the one with the predrilled hole, clamp the " bed" angle so that the line is just visible.The top and bottom fixed angles are clamped to the line with the bed angle back just enough to take into account the thickness of the material to be bend. Then simply bend the tab to 90 degrees. Hand pressure was all that is needed. Of course you should practise on some scraps before trying the real bend!
For the bend on the next sheet simple move the bed angle back 1/32" from the line and make the bend. This allows for the overlap of the tabs. 1/32" is real close to .032 and I just used a scrap of material between the line and the bed to get the proper distance. The result is a perfect lap joint
I cut the short angle the same length as the tab to be bent. The "bed" angle, the angle that the tab bends around has the sharp edge filed off to give a nice radius. On the picture you can see how the bed angle has a round radius. I left the plastic on to limit any marking of the material during the process. Mark both sheets with a line as documented in the plans. Put a line on top and bottom of both sheets and then lay the sheets together to varify that the lines are in the exact same locations. Mark on the sheets which tab bends bends up. On the first sheet, the one with the predrilled hole, clamp the " bed" angle so that the line is just visible.The top and bottom fixed angles are clamped to the line with the bed angle back just enough to take into account the thickness of the material to be bend. Then simply bend the tab to 90 degrees. Hand pressure was all that is needed. Of course you should practise on some scraps before trying the real bend!
For the bend on the next sheet simple move the bed angle back 1/32" from the line and make the bend. This allows for the overlap of the tabs. 1/32" is real close to .032 and I just used a scrap of material between the line and the bed to get the proper distance. The result is a perfect lap joint