Just trying to rule out a possible red herring. There are 18 posts where people have included output from the Marlin controller (RAMPs and RAMBo) and no one has mentioned the message “echo:SD init fail” as a problem. Plus the V1Engineering RAMBo, as far as I can tell, does not even have an SD card. Can I ignore this message?
As an aside, I have been making progress with the MPCNC. I got the X, Y, and Z axis(s) working. I drew a simple image with the pen attachment. Then I remixed the over-engineered pen holder and the MPCNC Tool Blank to mount the new pen holder and drew the outline of one of the MP3DP. Finally, I mounted the Dewalt router and started to level the spoil board. Everything was working great, but I was having to hold the wires as it went back and forth. Plus it was generating a lot of sawdust in my office. So I stopped, removed the router and electronics, and carried it into the garage workshop. I ran 15x30 drag chain for all the axis(s) and organized all the cables. It looks awesome. I reconnected the Raspberry Pi and RAMBo. My motors are connected as shown in Ryan’s diagram. cncjs connected to the RAMBo. Spews out the normal bunch of gcode. But after the “echo:SD init fail” message, the RAMBo does not respond to gcode entered into the console widget. So I am asking. As soon as I get this back up and running I will post pictures. Thank you.