I joined the left side skin to the longerons. Using the �nch a/c nails from Aircraft Spruce Co. The next day after drying I trimmed the skins to the longerons using the flush bits purchased from Amazon. DAMN! The ball bearing flew apart – thankfully wearing a full face shield as I trimmed – the broken bit dug a 1/8 inch dip into the longeron and skin. Not a big bite but unsightly. I will fill with wood epoxy when time to “finish” the fuselage.