First power-up and first calibration test, the one built into easel using screen icons. Moved z and x - looks and sounds fine. But Y gave very rough sound. Not the sweet sing of steppers.
On inspection, x rail not exactly perpendicular to y rails. So we turned off and forced the y2 stepper gear to jump along a few notches of belt. Works fine now.
We must have gotten the x rail katty-wumpus when threading the belts. If I was assembling another, I’d do quick check with builder’s square that x rail is perpendicular to y rails.
Hey, your problem seems really familiar! Don’t blame yourself for the out of square condition, it could have easily developed after you buttoned up and ran the first machine set-up test.
When I built and tested my second machine I noticed the same thing you observed, (X-rail catty-wampus relative to the Y rails) I also blamed my self for sloppy assembly, but it was the stepper connections.I found a dodgy connection on the y-1 molex connector that caused the y1 stepper to cut out or lock up intermittently, but only when I was trying to carve.
Also, no reason to force the y-belt to jump teeth in that situation. For whatever reason, the X rail does occasionally end up out of square to the Y axis. In my (school) shop it’s usually because one of the kids left the allen wrench we use for clamp tightening in one of the clamps. The rail jams up against the wrench, twisting the machine out of whack as it makes a nasty sounding GRRRAAAAAAAKKKKKKK. Loud enough to hear and bring me a-running even with band-saws and sanders screaming in the shop.
After gently chastising the kid, I just power down the machine, roll the rail (both hands please, one on each side of the gantry) backward to the stops and then forward again to wherever I need it.
With everything powered down you should be able to easily move the machine along the x and y axes by hand. Experts are cussing me now and say, “Only move the machine under electronic control”. But I’ve got 2 machines in a middle school shop environment. My (11-14-year-old) students hand-jog the spindle carriages all around all day long. No damage to an x-Controller or to an Arduino/G-Shield in 3-1/2 years. We even made little hand wheels for the Z axis so they can lift the bit clear of the work-piece and clamps with the machine powered down.