Need help Homing sequence in H-bot( CoreXY) system
Dear CNCZone members,
I'm from KOREA and this is my first post.
It's a long story.
Since 2 years ago, I have made my Micro-CNC adopted H-bot(CoreXY) system. Actually, my machine was built for 3D printer. So its controller was Marlin firmware based on Arduino.
Because I wanted PCB milling and simple AL routing, I had changed my machine to CNC milling machine with H-bot system.
Then since 2 months ago, I have adopted my control system from Arduino to Linuxcnc, because Arduino based firmware has many leakages for CNC work like engraving, miiling and routing.
Regarding H-bot(Core-XY) system,
as you know, it has coupled joint of X and Y axis by one timing belt. If you want to move tool head in X or Y direction, it should drive X and Y motor at the same time. If not, it's tool head will move diagonally. Simply, it need to drive 2 motor(X and Y) at the same time.
For this reason, I already installed the core_xy kinematics component to Linuxcnc system as refer this topic.(CoreXY + LinuxCNC (PopFab). ? ?????? ? ??? ?? ?????? cnc-club.ru, CoreXY + LinuxCNC (PopFab).)
Finally I've got the proper movement of tool head using Core-XY kinematics with Linuxcnc controller. (only world mode)
However, the problem is that, before homed all axis (joint mode), Linuxcnc allow to move only one axis movement.
In case of H-bot(CoreXY), at start of operation, when I press X home button, H-bot machine's X and y axis move diagonally because Linuxcnc drive only X motor.
So, machine's gantry will press the unwanted homing switch, Linuxcnc shut down the machine with Error message.
Currently, I've only driven my machine in world mode with No homing sensors. This mean is that my machine don't know the tool's exact point in XY work area.
I plan to adopt tool change and length measurement automatically during PCB milling, so my machine needs to know the tool head's exact position.
I would like you to share your ideas that solved this H-bot system's homing problem.
- Is there method to allow to follow the kinematics in joint mode?
- Is there method to find the exact XY point using home or limit switch after homing in arbitrary point?
( Googling youtube about Linuxcnc delta kinematics robot, also some delta bot performs homing sequence in joint mode!!
But I don't know how they can..)
I really apprecicate your attention for my long story and I'm looking forward your reply and comments.
Thanks in advance.
Need help Homing sequence in H-bot( CoreXY) system
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