6040 CNC w/ TinyG V9 – odd axis stall at end of move

Here is a link to my full $$ output
Link

Motor timeout was set to 2 seconds. Tried bumping it up to 4 seconds, but no change. Power to steppers is set to max (1), Power up when in cycle. I also switched the settings to run Y off a different driver, but had the same result.

As for energizing the motors and moving the gantry. Generally I try to avoid moving any axis manually when it’s plugged in and powered to prevent back feeding power to the drivers. Given that this is my first ball screw machine (my others are rack/pinion), I’m not really sure what the “rules” are for pushing it around when disconnected and what sort of force should be expected. However, I did try to manual move it with the stepper disconnected from the control board. It’s actually requires a good amount of force to push the gantry back/forth. With my luck, I got a feeling that there is something binding up, but I’m not sure the best way to go about fixing it. I noticed that one of the linear bearings on the underside of the gantry had it’s jump/spring ring tucked behind the round black flange piece that normally is behind the ring. I was able to snap it back in place and then unscrewed the block from the gantry to make sure it was able to slide along the rail ok. I can adjust the preload on the linear bearings with a set screw and found them to be tightened down lightly (not loose, but easy to break free and unscrew) I’m not really sure how to make adjustments to the ball nut setup on that axis…if there is a preload adjustment or if I could unscrew the main nut and test to see if the machine slides back and forth freely. I really don’t want to end up having the ball bearings dump out. I did notice that ball nut had a little screw that seems to be for lubricant. Speaking of which, there isn’t a HEAVY coat of lube but it’s certainly slick. I may give it a squirt anyway for shts*giggles. Ultimately I know that the 4 linear bearings (2 per side) and ball screw (middle) should be as parallel as possible. It would be nice to know the typical adjustment or starting points for squaring/alignment.

Oh lastly, slowing down the speed seems to help but there does still seem to be a somewhat abrupt stop at the end. Not the stalling/crunching/jumping necessarily that you find at the “faster” rates. I got the impression there is something going on mechanically, but hopefully you’ll have some suggestions.

Thanks

I wanted to update a couple things to post findings. I have a buddy that is running a shopbot control card that is essentially their SAM board for running G2 w/ external gecko 250x drivers, 3.5A steppers, 48v psu. He was having similar issues with his x axis on his microcarve cnc. They weren’t nearly as pronounced as mine but it was at the deceleration point as he moved his x axis back and forth. His settings are relatively modest, similar to mine with jerk values set at either 50 or 100. Here is a video of his YouTube Link

Regarding mine, I tried removing the stepper from the coupler to test without any load and had the same results. The stepper seems to handle the higher speed rates but locks up at slower rates. Doesn’t make much sense to me. I replaced the power supply in the machine as well as swapping out the stepper motor from the x axis with the Y and found the same behavior on the Y axis. Just to test some more, I hooked up an arduino uno to a Tb6560ahq driver that came with the 6040 and ran the motor off an atx power supply @ 24v. While I couldn’t achieve the same top speeds (not enough juice from the atx psu I assume), I didn’t have any issues running the stepper at various speeds. I don’t know what the max speed in mm/min the 6040 CNC 3A steppers with a tinyG v9 TI 8825 2.5A drivers are supposed to be, but the concern is obvious that these higher jog/rapid speeds are fun but cutting is going to happen at lower rates. I’ll write a few macros and try to nail down the exact range where the motor locks up. Any other ideas? Drop down to fb=83.09?

Thanks