I just installed the BT system on my Airwolf HD. Matter Hackers told me to attach the mag plate directly to the heated bed (discarding the glass plate).
After leveling the four corners of the build surface, I notice the center of the build surface sags a little so that is a larger gap between the nozzle and the build surface.
I have not printed anything yet.
I plan on inserting a couple of metal spacers under the heated bed....between the heated bed and the aluminum mounting plate to raise the center of the bed so it is level with the corners.
Has anyone had a issue with their surface sagging?