Square Drive Screws

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Square Drive Screws by Robertson: The perfect screw for veteran and vintage car timber framing work

       
Square Drive Screws invented by P. L. Robertson in 1908, have been in use since then.
The USA and Canadian motor body building industry throughout the days of timber framing used Square Drive Screws
to improve and strengthen the joints made, reduce build time with minimum cam-out of the driver as shown on the graph above.

Features of the Robertson Square Drive Screws: 
Reduce cracking and bursting of the wood with the sharp thread angle
Optimised thread depth to thread spacing ratio to minimise crumbling between threads
Thread surface is nearly perpendicular to the thread axis to provide greatest resistance to pullout
Minimum body diameter causes least possible material distortion
Sharp point and rapid rise provide easy penetration and a full thread within just one revolution
Square recess provides maximum driving torque - reduces driver bit cam-out