Before you start the calibration check if you have the grid calibration enabled in the smoothieware config file:
My config has this:
#Example for the delta grid leveling strategy
leveling-strategy.delta-grid.enable true # Enable grid leveling
leveling-strategy.delta-grid.radius 140 # Grid radius in millimeters
leveling-strategy.delta-grid.size 29 # Grid size, must be an odd number
The bigger the grid size, the more points it will test and the longer will take.
Heat the printbed to the temperature you normally print with.
Do the grid calibration:
;bltouch alarm release
; probe pin down
; set bed temp to 80C
; do delta calibration
; save trim to sdcard
; probe the grid and enable grid compensation
; save the grid to sd card
;To set the zero for the print head
;Make sure there is no left over material on the nozzle ( maybe heat and wipe it )
;go close to Z=0
; put a sheet of thin paper under the nozzle
; Then move the head ( using the printer controls ) until it presses on the paper sheet, until ; you feel the friction when you pull on the paper. This is the Z=0 point
; Use this point as the homing offest
;save to SD card
But even after all this it seems the prints are still not all right, so another option is to do some manual calibration of the hotbed using some springs.