Thinking of mounting the electronics on the Z carriage

I am in the middle of upgrading my Shapeoko 2 to an XCarve. This will initially be a 900mm (Y) x 1000mm (X) build and eventually be 2700 on the Y (supported by makerfoot). I am using a TinyG as the controller and NEMA23 motors.

One issue I have with the Shapeoko/XCarve design is that endstops are REQUIRED for both max and min. They are vital safety devices on a machine with a dangerous handtool attached to it.

Something I would really like to do is to minimize the length of all the wires and in particular eliminate the need for any electronics on the Y axis. It seems to me that the best way to do this would be to put the TinyG on the Z carriage. This would mean that the only wires absolutely needing to go through the drag chain are:

2 Stepper motor Y (18 AWG shielded 4 core)
(one approx 1 m, the other 2m to go back through the gantry to the other side)
2 End stop signal wires (22 AWG shielded 2+2 core)

In addition, need the following to the carriage but not necessarily through the drag chain:

  1. Dust collection hose
  2. Power to router (110V)
  3. USB to TinyG
  4. 24V Power to TinyG

2 through 4 could go through the drag chain or be connected to the dust collection. That will connect up to my overhead DC line

To make space on the new carriage, I am thinking of lengthening the Z axis to 250mm or perhaps a bit more and raising the drag chain by 25 mm. This gives me a space between the top of the carriage and allows me to re-use the space set aside for the junction boxes to place a mounting strip on which to attach the end stops.

This should allow me to isolate the moving gantry from the Y which allows me to lengthen or shorten it as needed.

Right now, I haven’t built the base so there is nothing to not be broken.

I agree that it is two stepper motor cables and one end stop cable (2+2) in the drag chain either way. So it might make sense to put the TinyG on the Y gantry instead. That way I still have the gantry isolated as a separate unit and can lengthen or shorten the Y axis at will.

Another option would be to place the end of the drag chain in the center of the Y-axis (maximum extension). and then mount the TinyG in the drag chain support. That would mean keeping the length of the longest cables to the length of the gantry + half the Y, or about 2.5m

I have seen OX CNC builds where they mount the controller board (Usually a TinyG) on the gantry opposite the Z axis.
Though I have not hand any issue with my GShiled on top of my power supply next to my XC.

While crashing the rail is bad it is not terrible as it could be because with a belt driven system the belt will slip first before a more catastrophic failure can occurs. I consider it a good safety feature for a hobby machine.

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