Hello all

We've had a few issues in the past with our Y2 motor that moves our gantry on our 5'x10' Precix CNC Router
Thus it's been taken on and off a number of times.

We can never seem to get it to align perfectly with the Y1 motor and this we get what looks like chatter or back-lash issues (zig-zags as I call them) along curve and angle cuts.

I'm wondering....what can I do to get the two motor lined up as closely as possible?

Also...how can I be sure the cog on the Y2 motor is riding perfectly along the rack.
Should I be pushing the motor up as closely as possible to the rack so the teeth are right up in there or should the teeth be backed off a little?

Finally...speaking of chatter....are chatter and back-lash the same thing or completely unrelated?

Any suggestions would appreciated.

I've included some pictures of the cut issues we're having as well as a diagram.
The diagram shows a circle cut....the chatter/zig-zags always happen in the same place on the circle no matter where on the table I cut.

Thanks everyone.
Ryan