Concord special parts

Left to Right:

1. - M3 Threaded Insert - (RivNut) Note - These can be made for Meccano threads or any other.
2. - Fin screw - 2 off - Meccano set screws shortened to 3/16" to suit part 3
3. - Fin Mounting Bolt - 2 off - ¼" Sq x ½" long with slot on Centre line, 2.5 mm wide x ?" deep - One face drilled Ø 13/64" to clear set screw head. Opposite face - Meccano threaded. - Bolt section, M3 thread x ¼" long.
4. - Threaded spacer M3 through x 0.550" long - 4 off ¼" A/F hexagonal