Quote Originally Posted by AndyUK View Post
Thermal linear expansion coefficient of Steel, ballpark 11.5 x 10-6m/(mēC). Aluminium is 22.0 x 10-6m/(mēC). The difference is therefore 0.01mm per degree, per meter of material. Lets say expected temperature variation of 30ēC maximum, on a 1 meter long gantry. Worst case, 0.3mm. Assuming M6 with a close fit clearance hole, still got another 10 degrees C before you start to stress things.
Thank you! that was an "oh right!" moment for me!