Do any of you use a granite plate offline to check parts? If so, do any of you have a thread insert pattern on it? I am about to by one and am trying to decide what would be the most helpful hole patter to have. I was thinking about staggering some 3/8-16 inserts along one short edge about 3 inches in. 3ft*6ft*12inch granite.
CET of granite is about 6 µm/m/K (between 4.5 and 7.5)
Aluminium is about 23µm/m/K.
If the plate is screwed on the granite at each end, a difference of temperature could create a pitch (twisted) of the plate, maybe more important than the granite flatness...
If you edit the compensation matrix of your cmm, looking at the straighnesses LXZ and LYZ will give you a idea of the defects, even if it's on the guide ways and not on the whle surface.
CET of granite is about 6 µm/m/K (between 4.5 and 7.5)
Aluminium is about 23µm/m/K.
If the plate is screwed on the granite at each end, a difference of temperature could create a pitch (twisted) of the plate, maybe more important than the granite flatness...
If you edit the compensation matrix of your cmm, looking at the straighnesses LXZ and LYZ will give you a idea of the defects, even if it's on the guide ways and not on the whle surface.
