About this 3D model

I kept having some delamination on the screw part of http://www.thingiverse.com/thing:2521 if too much force applied.This file uses M4 hardware. You will need an M4x16 bolt and a half-height M4 square nut. No filing on the slot or whatsoever required to fit.You can change the sizes in the dxf file and extrude it with OpenSCAD.