Problems Calibrating Delta

So I am trying to calibrate my My new delta printer but I am having problems with Z accuracy.

; do endstop and delta radius calibration
G32
; Home
G28
; move to 5mm above bed
G0 Z5
;  then manually jog down until nozzle is on bed or just traps a sheet of thin paper
; sets the Z homing offset based on current position
M306 Z0
G28
G0 Z1
; check nozzle is 1mm above bed
M500
; saves the results in EEPROM equivalent

But when I do a G0 Z5 I am about 15-20mm off the bed instead of 5mm, then I jog down to the ben and perform M306 Z0 then G28 then G0 Z1 and then I am about 10mm.

Is there something I’m missing? Is there a step by step calibration guide that I could use? I have read through the docs and have not clear instructions on where to start.

I am using the smoothieboard

I also posted this on the smoothieware support google groups with a config file but I can not post links.
search for title “Problems Calibrating Delta” By sgibbers17

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