Old style start for program?

I always try to use the analogy of setting a part up on a CNC machine to explain the three alignment steps (level, rotate, origin). When you level, that is like sitting the part on the machine table - it can no longer move up or down and can only slide left or right, forward or back or spin around whilst staying on the table. The next step would be to square the part up by running an indicator along one of it's sides or pushing it up against a straight-edge or some dowels - that is the rotate. You are stopping the part from spinning around on the table. Finally, you might slide the part up against a stop or run an indicator around a bore to determine it's centre before bolting everything down tight - that's the final, origin. Now the machine can move to any point on the part relative to your work-offsets - or alignment in CMM terms.

I always try to use the analogy of setting a part up on a CNC machine to explain the three alignment steps (level, rotate, origin). When you level, that is like sitting the part on the machine table - it can no longer move up or down and can only slide left or right, forward or back or spin around whilst staying on the table. The next step would be to square the part up by running an indicator along one of it's sides or pushing it up against a straight-edge or some dowels - that is the rotate. You are stopping the part from spinning around on the table. Finally, you might slide the part up against a stop or run an indicator around a bore to determine it's centre before bolting everything down tight - that's the final, origin. Now the machine can move to any point on the part relative to your work-offsets - or alignment in CMM terms.