Overengineered fix for falling gantry

[LipSanFlip]

Prior to doing the belt upgrade, I had the problem of the gantry falling once the motors were deactivated. To me, this is good because it means there's little friction in the system. I thought the belt upgrade might eliminate the issue but it still happens. I don't want to tighten the belts or wheels which will fix the problem but introduce unnecessary friction.

I designed something that will automatically hold-up the gantry indefinitely without adding any friction to the gantry's movement.

Here's a couple of videos of the system working: https://photos.app.goo.gl/zV6mKcoV1G37CLrb6
Here's a picture: https://linksharing.samsungcloud.com/cSFTGpRe3txx

Here's the script that controls the servo. You can run it along with your "END" and "CANCEL PRINT" code.

[gcode_macro PARK_GANTRY]
gcode:
G28 # home
G90 # use absolute coordinates
G1 Z50 F3000 # raise Z to correct height
SET_SERVO SERVO=my_servo ANGLE=21 # lifts arm to park position
M84 # disable steppers
G4 P1000 # wait for 2 seconds
SET_SERVO SERVO=my_servo ANGLE=150 # moves arm away

Here's the code from printer.cfg to define the servo:

[servo my_servo]
pin: PC2

In addition to the control pin, you just need a 5v and ground from anywhere on your controller board.

Someone might find this useful - Ken