Bed level issue
So how do I overcome this issue in the attached image? The front is pretty good but the back left and right are not as close. If I just lower the back with bed correction, it's going to help but make the back right way off.
After doing an outline of a print and measuring the first layer these are the results I've got.
I've checked all the feet and they are level. The Y rods are sitting flush and all bed screws are tight.
Re: Bed level issue
Your bed geometry has 0.09 deformation between front and back. Considering the height varition is over 200 mm distance, each mm raises 0.00045 mm. I'm impressed how you measured the height variation of the bed. My suggesting is to use a precision torque wrench for the mounting bolts.
Any material contracts and expands by heat. The print bed will have different geometry as target temperature changes.
http://homepage.ntlworld.com/r.burke2/precision_modelling_006.pdf
Putting Size into Perspective
♦ The human hair is around 76 microns thick.
♦ Most general purpose machine tools in
skilled hands would be able to work within
two thousands of an inch (50 microns)
♦ The best CNC machining centres can
position to an accuracy of plus or minus 3
micron, with repeatability of plus or minus 1
micron.
♦ A 100mm-iron bar will expand 0.012mm with
a rise in temperature of 10 degrees C
I used to analyze bed flatness in my first Delta 3D Printer to fix bad first layer.
One lesson I learned was that auto bed leveling can't fix mechanical problem.
As long as you get the printing quality from a 3D Printer, minor deformation of print bed is fine.