Y-Dimension Errors during milling

I am working with a Stepcraft 840 and I am experiencing dimension issues in the direction of the y-axis. A previous email to support@stepcraft.us gave some suggestions (workpiece not secured completely, play in the gantry, incorrect tool diameter); however I have checked these possibilities and they have not corrected the problem.

I verified that the issue is with the y-axis by cutting two identical, but orthogonal slots (6 mm width). The slot with its width cut in the x-direction was correct, however the slot with its width aligned with the y-axis was undersized by 0.6-0.7 mm.

If anyone could provide some suggestions for what might be causing this issue, I would appreciate the help. Apologies if this is not the correct section of the forum to post this.

Logan
Impulse Technology, LLC