Is this a tram adjustment?

curious, noticed an issue when I did a large project, the back of the carving area did not vcarve as deep as the front. i have attempted to make a device to check the tram…not sure how to measure the distance changes from front to back or side to side. wouldn’t know what kind of gauge to get. resurfaced spoilboard incase that was causing the issue, and when I did, my 2x2 grid remains on the back side, it fades from about 8 inches from the back, to not touched on the very back. see picture. when I put a level on gantrys, and spoilboard they seem perfect. anyway thought I would throw this out here to see what experience can tell me.

Most likely the spoil board is not flat and/or not coplanar to the machine. In this thread there are many approaches to tramming the machine that could also be used to check for flat and coplanar as well, most require a dial indicator.


Thank you sir. Will follow up on those suggestions.