CR-10 S5 Bed Modifications

This is a solution to my CR10S5 bed leveling issue. When I purchased it, the bed was out of level >3mm. After I finished with the changes I have around .5mm variance in the build plate when warmed up. One of the pictures has the readings. The readings were measured from the top of the x rail.

After initially trying to adjust the bed level, I had the left two bed leveling springs tight and the right two loose. After heating up the center was bowed up >1mm. I about returned the printer but decided to keep it. It is too big for my workspace but I already had some items ordered from TH3D to put on it. (Magnetic build plate and EZABL) Anyway I thought I would share the experience and the details are below.

1) I removed the bed to figure out where the issue was. The first thing I noticed was a 300 mm heated build plate mounted on a 500 mm plate. Surrounding that 300 mm heated build plate was an aluminum structure which looked like a way to keep the plate somewhat level. I