@RD
Plates flex before failing giving the structure a chance to absorb the impact and distribute the forces. A rigid mount assembly will transfer the load to the next weakest point.
If you cant use a plate then use good coarse thread sheet metal screws in predrilled holes. You want the drill size to be smaller than the minimum screw diameter (minor pitch dia) to make a pilot hole. The screw will then cut a nice clean thread in the wood. Unscrew them and use thin CA glue to toughen the wood grain. Assemble the gear and check fit.
If you use a blind nut and dont have access to the back of the rail then the blind nut will aid in splitting the rail because it has a larger diameter shank. You must predrill the hole on the back side to clear the shank diameter to do it right. It will be a stepped hole not a clearence hole all the way thru because then the screw can move within the diameter of the large hole.
Using a machine thread which is a fine pitch thread is ok but not ideal. The threaded wood doesnt offer as much leverage to compress the assembly when you tighten the screw. If its long then yes it does a better job but if its a short screw then I would change to a coarse thread sheet metal screw.
If the retract flange is about 1/8 in thick then you want a screw that is a minimum of 1/2 inch or longer if your using washers also.
Post a photo of your retract install and the guys here will be happy to give you better suggestions.
Last edited by Chris Nicastro; 05-15-2015 at 12:53 PM.