My xcarve is 500mm, NEMA 23 steppers. The steppers were purchased from Inventables. Last night, I tried to cut acrylic with a single flute 1/8" uncut at 0.02" DOC and 80 in/min feedrate. It was SUPPOSED to be 0.01" DOC. The machine tore through the material and roared loudly as it went. Shortly after the cut began out stalled while traveling in the Y direction for several seconds, causing several inches of missed steps. The machine then veered off to the side, suggesting that the X axis was not jammed. It tore through a wooden hold down and then stopped after I killed the power. Now, occasionally, the thing gets jammed while running a simple job at cut settings that have always worked before. Missing inches of steps while making a grinding noise. Any thoughts?
Just spitballing here, but could the belt have been damaged? Ridges worn off?
I have had mine skip steps due to wrong feedrates or running into something but it’s never created an ongoing issue.
Grinding noise is just the stepper loosing steps, nothing to worry about as its not harmful to the stepper (not ideal but not destructive either)
After a crash like that you need to examine the wheels, belts and pulleys for potensial damage or misalignment.
The belts and ridges look good. My machine is really filthy. I’m trying to clean off the rails, I’m worried that the V wheels are just getting caught on debris or are themselves destroyed from years of lazy slob machining.
The wheels are sticky with dust from wood carvings. I blow on them, wipe them with paper towel and my fingers very often, but they’re still a few years old. I probably need to replace my V Wheels… 
Actually, I ran an air test carve above my workpiece and found that my Y axis motors were easily overcome with my hands. Nema 23 motors should be a little stronger, right? I’m going to search through the forum for potentiometer position suggestions for a stronger Nema 23 setup.
Figured it out! My X, Y, and Z potentiometers were running at 0.95, 0.95, and 0.85 volts DC respectively.
Thank you @LarryM for your guide here and thank you @RobertA_Rieke for your guide here. I’m tuning the motors right now and will update with the results.
I adjusted the X and Y pots to 1.95V and the Z axis to 1.45. When running Robert’s test, I was able to stop the Y axis with one finger 
Now it’s very difficult to stop it in either X or Y direction. New cut turned out quite well!
Woo hoo!! Congrats on solving it.