Could it be a pulley slipping on the motor shaft ? The unexpected turn looks very much like the shape of the contour it would have followed a few inches further down the toolpath:
If the dotted line I added is your X axis, I would definitely triple-check the setscrews on the X-motor pulley (you know the drill : one of the two set screws MUST be on the shaft’s flat, both must be tight, you can draw a line with a marker across the shaft and pulley to check if the pulley slipped, after a cut event like this)
Given the set-screw shaped dent in the extrusion rail it would seem to be a good idea to go check that all the pulleys on the machine have both the set screws homed and tight.
Indeed ! I didn’t even remember that other thread, but maybe @dandangerous is on the money, maybe a setscrew fell off completely, causing this AND the rail dent.
Just checking in case there is any misunderstanding (and please accept my apologies in case I’m stating the obvious), but it’s not possible to see whether the pulley setscrews are there from those pics, they’re the teeny tiny screws inside the threaded holes in the pulleys on each motor, and I must say it’s far from obvious to visually inspect them without removing them.
If you did check them and can tell for a fact that they are still there deep down inside their holes, then the mystery remains.
To piggy back on what Julien said, whether you did or didn’t check them visually, I would suggest checking them physically by trying to tighten them.
As an aside, you may already periodically do this; however, brushing off your v-wheels and transmission components will help ensure your machine is performing at its best.
The set screws are standard M3 set screws ~4.75mm o.a.l. which can be sourced at any decent hardware store. Some folks replace them with M3 SHCS of a suitable length (~8–10mm). If you can’t find them locally or that’s not an option let us know at support@carbide3d.com and we’ll get a replacement out to you.
Replace the set screw and re-tension the belt per your assembly instructions.
Yes, if the pulley isn’t holding in one direction then the machine can get bogged down and pulled into another.
@Bonhoeffer: but I guess still triple-check that your X axis pulley set screws are also tight and one of them is against the flat. Better safe than sorry!
No problems with clearance on X or Y steppers. Not sure on the standard belt driven Z (I have the Z-Plus), but imagine the same. Use the low-strength purple threadlocker to keep them from backing out. These screws are really important - the entire drive and rotational force of the stepper is transferred to the screw which then transfers it to the pulley, then the belt, etc. They are the only mechanical interface to transfer power from the stepper onward.
Interesting how many threads are related to these 5 cent screws…
