Need to understand Z Axis configurations

[Sairfan]

I was able to run Marlin with 5 Axis on RAMPS board, I was also able to configure X, Y, Z, A and B Axis to move correctly, I understand Homing and Parking X,Y Axis.

My machine is configured for Shared Z Axis Negated Head 

I was not able to understand how to configure Z Axis, for example if I move the machine to some location, I aspect that Z Axis should first move to a safe position like none of the Nozzle is down, then it should move to X,Y location.

After Homing machine Z stops at '0' with right Nozzle up and left Nozzle down, at Z 61mm position right Nozzle is max down and left Nozzle is at top position. From Z Axis Home position '0' to at Z 30.5mm both Nozzles N1 & N2 are at equal height.

Can someone help me where to put these values to work correctly, I tried by putting values at MappedAxis Z2, 

Map Point A: 0 -> 30.5

Map Point B: 30.5 -> 61

But did not work.

Then tried by setting Node VirtualAxis RotationTop 

Home / Safe Z: 30.5 

And also tried setting VirtualAxis zTop 

Home / Safe Z: 30.5 

I was getting help from OpenPNP Wiki, I believe, I misunderstood Z Axis configurations.

Please help.

[Leoyu.PandaPlacer]

Hi Sairfan,

I have successfully configured the Z axis machine setting, also I am using marlin with X Y Z A B axis, also Z max length on my machine is about 61mm(90mm MGN9 rail), I guess we have similar Z axis disign.

My Openpnp2 setting is:

    ReferenceMachine>Axes>    add a "ReferenceMappedAxis"（to create a negative Z target value for axis B）  > 

        Type: Z;  Name: Z-neg;  InputAxis: Z; Map Pont A[0 -> 0];  Map Pont B[1 -> -1]

    

    ReferenceMachine>Heads>ReferenceHead H1> ReferenceNozzle N2(Nozzle2)>

        Coordinate System>

            Z: Z-neg ;  Rotation: C2(B axis name in your setting);

    Also, you may need to move two nozzle to stay at equal height after Machine Homing, my solution is by setting HOME_COMMAND in GcodeDriver:

        G28 Z; Home Z first!

        G1 Z30.5; MOVE Z to middle hight(Adjust if needed)

        G92 Z0 ; SET current Z hight to 0(Middle)

    Now the Save Z is 0, Middle hight is 0, simple and worked well on my machine.

I think these will make your Z axis move correctly.

Have fun :-]