Hi i have lurked around here for a long time and have found all the answers needed to build my MPCNC. I love the machine and have gotten a fair amount of use out of it. I have used F-engrave successfully many times but tonight while cleaning up a male part the machine walked off on me about 15 mm in the -x direction. What would cause this?
I put the file back into CAMotics and it displays with no errors so i figure its mechanical.
That being the case and being a believer in starting with the simple things, it can’t hurt to check the grub screws.
I second the grub screws. 
Besides your little problem: The edges of the letters are really crisp and good looking.
I don’t know that potato bug looks pretty suspicious to me!
Have you tried running it above the piece to see if it does it consistently? I’ve had issues like this and a corrupted SD card was the culprit.
Ha! Did not even see that little guy! I will check the grub screws and run the file above. I am running via octoprint and a Pi. That should eliminate corrupted SD card issues? maybe?
Shouldn’t be an SD Card issue since you don’t use one.
Grub screws all felt tight. belts maybe a bit on the loose side though. When i went back a measured it the origin shifted 25mm in the negative x direction. That seems like an impossible amount in such a short period of time.
Did you check that they were bearing on the flats machined in the motor shafts? I don’t trust them if bearing on a round shaft.
If they aren’t loose enough to spin clear around they will go from edge of the flat to the other as direction changes. That is hard to see without locking the motor and twisting by hand both ways. Eventually the screws fall out and then you can tell easier.
If you can see the end of the shaft through the pulley center, drawing a line across the hub and shaft with a marker can make it easier to discern if the grub screw isn’t holding tightly enough.
They were initially installed on the flats and with lock tight. Had to break the lock tight yesterday when checking torque. Will probably completely disassemble / reassemble to be sure.
After checking they were tight I ran a few file in air and everything seem perfect. I am wondering if there are certain conditions that make slippage more likely? Only doing 1mm DOC 15mm/s. By sound and chips that seemed perfect but wondering if that it too much and leads to slipping?
Did you move the machine or add a new motor or frig or something to the circuit it is connected to? When i added the mimi frig to my work area it caused a problems for me for a while
All grub screws tight on the flight part and now marked for the future. None seemed loose. I have not moved the machine or added anything to the circuit. I did redo some wiring two jobs ago so maybe it was just acting up. Several cuts today with no issues but do not yet have the confidence to cut the vcrave into the nice cutting board to finish the project. back to foam I guess. Thanks for the ideas.
