So I thought all was well with my X2 with the X and Y axis motivated per Hoss's conversion designs when I realized that I can't drill holes where I think they should be. I made one part and the the profile dimensions were perfect. When I drilled a hole, it was .025 off in the x axis. I thought my math was off so I recalculated everything and made another part - exactly the same error. (at least I'm consistent!) After making two blems- I decided I had to figure out what was going on. I discovered that when I center drill a pilot hole with a .25 center drill in a collet then used a .323 drill in a chuck, the centers were not even close. I had trammed the mill with minor adjustment so that told me that the spindle was not aligned and while it was square with the table, the spindle center changed whith z axis movement.
I took the head off and loosened the 4 bolts that bolt the spindle block to the z-slider (I don't know what the correct name is) and after 3 attempts I managed to relocate the spindle so that the error is positive direction not the negative side.
So finally the question -- What is a good method of aligning the spindle so I'm not making swiss cheese any more?!?

Thanks,
-4ist