Thanks. I don't think indicating is that important here. The main thing is that it doesn't shift up and down, right? Y tilt (if there is any) would just change the distance to the scale, it wouldn't impact the interval between the marks. Same for the the X direction, it would change the angle of the marks, not the interval. If the interval is marked at 5um, the error due to any tilt would be even smaller - can be discounted as statistical error.
![โอ้เธอช่าง... - บี้เดอะสกา ft. ต๋อง เทวัญ (Prod. by ป๋าเพชร) [Official MV]](http://i.ytimg.com/vi/zbWhiLFmVL0/mqdefault.jpg)
Nice job, but I would indicate in both axes to be sure that the glass scale is parallel with the spindle. It should be pretty accurate.
Thanks. I don't think indicating is that important here. The main thing is that it doesn't shift up and down, right? Y tilt (if there is any) would just change the distance to the scale, it wouldn't impact the interval between the marks. Same for the the X direction, it would change the angle of the marks, not the interval. If the interval is marked at 5um, the error due to any tilt would be even smaller - can be discounted as statistical error.