Hi this is my first post on the forum, so I would like to start by saying Hello to everyone.

I have been working with cnc for a couple of years, I got a grizzly bench top mill with a cnc retrofit off ebay, thinking this would be a good way to teach my self how to run a cnc mill, so latter I could get a bigger mill to help with my business. I have done ok with one sided parts, surface finish is not great, and the tolerance is not good, but it seams to work ok. Three days ago I made a screw less vise and decided to try a two sided part, so I could get a finish on both sides and not cut through my vice. The result has been a headache for days. I need four parts, and last night I ran part seven off.
.Attachment 271224 The biggest thing is a misalignment of the two halves, Iv read that a vice flip is not a great idea but for this close would be fine, but its off by .020. Next after measuring dimensions the x- axis seam to be off by .010-.015 on some, and is within .003 on others, while the y is only off by .002, I have set up indicators and checked for lash, and the ability to return to zero, no visible problems. I have tried changing how I setup and flip the part (indexing from edge, then from center) but it dose the same thing in the same direction. Im starting to beat my head in the wall looking for the problem, dose anyone have any ideas, or things to check?
Attachment 271226
the machine
grizzly g8689 bench top mill
stepper motors with ball screws (already installed)
mach 3 controller
bobcad v25 cad-cam
( just a side question is this a good way to learn?)