A mix of wood flour and colloidal silica is a good combination for bonding/gap-filling. Just make sure you don't use any filler that is intended for a fairing mixture (like microballoons). If you do, you'll end up with a very weak joint.

Ross

> What sort of filler do I put in my epoxy to make a strong gap-filling
> glue? I need it to mount my foot braces. I am using a four inch block of
> hard wood at each end of the adjustable braces for mounting.