ArakAtak
Veteran XX
I recently set up a line to produce a similar detail.
200 dia bore with a -0/+ 0.03 tolerance - that's about. 001" for you people who haven't yet discovered metric.
It has 2 dowel holes each side with one located to .03 to the bore centre and the other relative to the first dowel with a pitch tolerance of 0.05
This Is in aluminium so the temperature growth is huge.
I made an aluminium master block to replicate the dowel holes and mounted it to the machine bed with one fixed end. I probe it every cycle and then compensate the position and pitch for each part. This removes thermal growth and any axis inaccuracies relating to the machine. You would need to make it from the same material as your workpiece
When measuring, unless you have temperature compensation on your CMM then you should soak the parts in the room for 24 hrs. Or you drag the CMM onto the shop floor and figure out what the pitch should be at the higher temperature.
Don't worry about the shape of the part, the growth is linear so calculate from the drawing dimension.
200 dia bore with a -0/+ 0.03 tolerance - that's about. 001" for you people who haven't yet discovered metric.
It has 2 dowel holes each side with one located to .03 to the bore centre and the other relative to the first dowel with a pitch tolerance of 0.05
This Is in aluminium so the temperature growth is huge.
I made an aluminium master block to replicate the dowel holes and mounted it to the machine bed with one fixed end. I probe it every cycle and then compensate the position and pitch for each part. This removes thermal growth and any axis inaccuracies relating to the machine. You would need to make it from the same material as your workpiece
When measuring, unless you have temperature compensation on your CMM then you should soak the parts in the room for 24 hrs. Or you drag the CMM onto the shop floor and figure out what the pitch should be at the higher temperature.
Don't worry about the shape of the part, the growth is linear so calculate from the drawing dimension.
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