Corexy - How to invert only the X axis direction

Hi there reprapers

I have just built a corexy printer with auto bed leveling servo probe.

There are number of issues come up every now and then.

1. When machine is turned on, the servo will shuffle a little for a short moment
The cable is around 40cm long

2. The X axis is moving in the wrong direction, I've tried to invert the X axis direction from the firmware,
but both X and Y directions will be inverted I.e. X becomes Y, and Y become X

3. The servo stops working every now and then, often needs to reset printer and keep all stepper motor cables well away from the servo cable to get going again.
But this problem will come up again after a while, not sure why.

4. I'm using an LCD "RepRapDiscount Smart Controller" to print offline, the Z movement is far too slow at the moment when I turn the knob
Where in the firmware do I need to alter to change the speed of the Z movement while "Not printing"

5. Due to the printer design, the SD card slot need to be located at the front panel of the printer,
I'd like to know how do other reprapers extend their SD Slot to other place of the printer ?

Many thanks

#1 : If you have a Digital servo, yes, it will jitter, that is normal.. if you cant stand it, then i suggest you get a analog one.

#2 : have you tried to invert the motor cable ? I had that same problem. my prints were inverted on the build plate compared to the computer screen.

#4 i'm not sure about this one. if the speed is the same as when homing, there should be some settings in Marlin that you can change.. (I can't at the code right now).

for the rest, cant help you there, sorry

J-F

#1 - Power the servo from the power supply (or other external) instead from the board. And some cheap servos have some jitter also, look for high quality one.

#2 - I had same problem and tried to invert the motor cables without success. I need X axis to be Y axis in my CoreXY. Still trying to find how to do it.

#3 - Try the #1 clue, servos are some power noise problematics.

#4 - Firmware sure, but no idea where it is.

#5 - External SD card reader (almost any board can) and not use the board/display reader. There's some not very expensive (15-20€) on ebay.