some update...the printer seem to be working correctly now! many thanks to all!
now,
i have to fix the last problem. i need to mantain the 4th axis 30mm over the current position after the homing, cause i have insufficient lenght as i mentioned before. and i have no possibility to move it up.
is it possible to do it via firmware?
at the moment i've made in that way and it seems to work properly.
any suggestion?
; homedelta.g
; called to home all towers on a delta printer
;
; generated by RepRapFirmware Configuration Tool v2.1.8 on Sun Jan 19 2020 19:28:23 GMT+0100 (Ora standard dell’Europa centrale)
G91 ; relative positioning
;*** Slow homing has been configured. Change F300 to F3000 below when your configuration is working
G1 H1 X325 Y325 Z325 U325 F1000 ; move all towers to the high end stopping at the endstops (first pass)
G1 H2 X-3 Y-3 Z-3 F600 ; go down a few mm
;*** Slow homing has been configured. Change F300 to F360 below when your configuration is working
G1 H1 X10 Y10 Z10 F200 ; move all towers up once more (second pass)
G1 Z-30 F1000 ; move down a few mm so that the nozzle can be centred
G1 H2 U30 F1000 ; 4th tower clearance of 30mm
G90 ; absolute positioning
G1 X0 Y0 F600 ; move X+Y to the centre