Help: New build homing improperly on Z axis
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So i just finished a build based on the HEVO using a duet 2 wifi w/ a Duex5 and triple independent Z steppers. I finally have all the motion moving the right way (bed drops away from the nozzle when homing and then moves up), the bed goes up to 0 and down to 500, the issue is when i try to home it, it tries to home at 500 (the bottom of the printer) even tho when it homes it will set that to 0.
; Endstops
M574 X1 Y1 S0 ; set active low and disabled endstops
M574 Z2 S0; Drives
M584 X0 Y1 Z2:5:6 E3:4 ; set drive mapping
M671 X-40:440:440 Y185:325:30 S1 ; leadscrews
M569 P0 S1 ; physical drive 0 goes forwards
M569 P1 S1 ; physical drive 1 goes forwards
M569 P2 S0 ; physical drive 2 goes backwards
M569 P3 S1 ; physical drive 3 goes forwards
M569 P4 S1 ; physical drive 4 goes forwards
M569 P5 S0 ; physical drive 5 goes backwards
M569 P6 S0 ; physical drive 6 goes backwards; homez.g
; called to home the Z axis
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; generated by RepRapFirmware Configuration Tool v2.1.8 on Wed Mar 11 2020 21:21:21 GMT-0500 (Central Daylight Time)
G91 ; relative positioning
G1 H2 Z5 F6000 ; lift Z relative to current position
G1 H1 Z505 F3600 ; move Z up until the endstop is triggered
G92 Z0 ; set Z position to axis minimum (you may want to adjust this); Uncomment the following lines to lift Z after probing
;G91 ; relative positioning
;G1 Z5 F100 ; lift Z relative to current position
;G90 ; absolute positioning
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@Holyman92 said in Help: New build homing improperly on Z axis:
G1 H2 Z5 F6000 ; lift Z relative to current position
Your homing moves are backwards. Increasing Z makes the nozzle/bed separation larger. To make that spread larger on a HEVO (and other moving bed CoreXY), the bed drops as Z increases.
You want -5 on this move and -505 on your endstop move. Moving Z to smaller numbers (negative relative moves) moves the bed closer to the nozzle; in other words, up.
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@Danal said in Help: New build homing improperly on Z axis:
You want -5 on this move and -505 on your endstop move. Moving Z to smaller numbers (negative relative moves) moves the bed closer to the nozzle; in other words, up.
now it moves up towards the nozzle when i home but when u add 5 to the z it moves up instead of down
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@Holyman92 said in Help: New build homing improperly on Z axis:
Your first 5mm move is correct as positive. The 505mm move must be negative.
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Correct. I forgot the first move is to move it away from everything.
Also, the -505... it is sort of tradition to do -999999 or similar. This makes it very obvious that this move is a home move, and the switch will end it.
Also, if your bed ever happened to be beyond 505 down (crammed into the bottom, for whatever reason), homing would fail with a -505, and frustratingly enough, fail JUST before it touched the switch!
Anyway, that's the two reasons for -999999
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@Danal said in Help: New build homing improperly on Z axis:
Anyway, that's the two reasons for -999999
That's a little extreme. If the switch fails your axis will grind away for the entire duration of the move. Maybe something a little closer to the axis length but still longer. 600 maybe?
