QTR-Quadtone RIP

Hello,

Does anybody know the secret to printing centered on a 2200, or at
least with exact margins? I have had this issue since I started
printing with the 2200, and on every program, Photoshop, Qimage, and
now QTR. No matter what I do, which settings I choose, which margins I
set, it is always lopsided,, with one margin larger than the others,
or smaller. Not too hard to deal with on a large print that will be
matted and framed, but on those 8x10 or 4x6 portraits it's really a pain.

My concern with QTR is that it has even fewer settings (going through
the GUI) than the other programs. All I can do is click "center" or
select a left and top margin. Center does not work, but the worst of
it is, selecting for example a 0.125 margin for left and top still
will not give me an exact 0.125 margin. 

Example: I will print vertically an image at 3.75 inches wide on a
paper that is exactly 4" wide. I will specify a margin of 0.125 to the
left and 0.125 to the top. I should now have 0.125 to the top, left
and right, but nooooooo (suddenly thinking of John Belushi), I will
have a margin to the left that is less than 0.125 (visibly) and more
on the right. Center does the same, and differences seem to be even
larger on letter size paper.

Any idea?