"I think you mean your spindle axis(Z)is not perpendicular to the XY plane (your table), right?"

Yes. I made sure the spindle was perpendicular to the carriage, but the entire transport assembly appears to not be fully aligned to the table base. The only way I can see to adjust it is with shims, or to face the whole table.

Here is the machine:

http://s1262.photobucket.com/user/Mo...slideshow/CNC2

If you look at the first photo, you see that the table seems to dip toward the lower left. It could also be that I just mounted the work poorly, among other things. The quick fix is to simply face the plastic block before the next run. Something I should have done first, but the block itself seemed pretty good.

"Do you have a link to the CNC machine you own?"

No. It seems to be hand built by the seller. There is "RT Technik" engraved on the front, but I found no web hits. Few of the components even have labels, but the seller says he got everything locally, and to contact him if I need any parts. Here in Germany there are maybe a dozen commercial manufacturers building machines like this, as well as many individuals making them in their garages and selling them on Ebay. I shopped for a year and this is what I chose. So far it seems like I did well. Much of the Mach3 controller software is still a mystery to me, but fortunately the seller walked me through the basics. The hardest part has been creating decent toolpaths using Bobcad26. I'm not sure that was a good decision, but I am getting the job done now, after like two months of despair.