Lately I've been testing high speed printing with my CoreXY printer (running Marlin firmware), and have been running into an issue with movements faster than ~250mm/s. At higher speeds, when decelerating, the gantry seems to "stick" for a very short time, causing a jerk in the movement. Usually this only happens during travel moves (since my travel speeds are the highest) and causes no noticeable problems. However, occassionally, the binding causes the steppers to skip, causing layer shifts and ruining the print.
Changing the acceleration seems to have no effect on the binding issue; I've tried everything from 500mm/s^2 to 4000mm/s^2 (the firmware limit I set). Also, the problem doesn't seem to be localized to one axis, leading me to think that the smooth rods and bearings aren't to blame. Running a few x-axis and y-axis moves with low acceleration, it seems that the binding occurs when passing a certain speed during deceleration. Changing stepper currents both ways doesn't change anything either.
Here's a video of the problem. It's kind of hard to see the binding at normal speeds in the video, so I've also taken 120fps high speed shots with my phone which shows the issue more clearly.
Changing the acceleration seems to have no effect on the binding issue; I've tried everything from 500mm/s^2 to 4000mm/s^2 (the firmware limit I set). Also, the problem doesn't seem to be localized to one axis, leading me to think that the smooth rods and bearings aren't to blame. Running a few x-axis and y-axis moves with low acceleration, it seems that the binding occurs when passing a certain speed during deceleration. Changing stepper currents both ways doesn't change anything either.
Here's a video of the problem. It's kind of hard to see the binding at normal speeds in the video, so I've also taken 120fps high speed shots with my phone which shows the issue more clearly.