a reliable method of measruing flatness ?

[Mranaskw]

Hello.

i have recieved today an easy task to evaluate my training , it was a couple of small pcb's ( 6 squared thin cards 3x3 inch)

i placed them on the marble,then i took a plan on that marble and aligned that plane to be a level an z origin , then took 4 points from each corner of the pcb (on the raw surface not on the circuits material)

then selected the flatness dimeniosning icon , and got really small values like 0.03

how bad was it lol


waiting for your opinions

[Douglas]

take more hits on the plane you are measuring flatness of, 4 is not enough.

edit... and space them out as much as possible all around the feature

[Don Meredith]

Most of the parts I measure have flatness points called out on the drawing, XY coordinates. Usually 18-24 points.

[Cumofo]

You need a canned scanning routine that levels to the centroid of the plane, then refits all the points to this "leveled" plane. One of the auto plane adaptive strategies does this. Set your filters to gauss about 2.5.