Porter Cable Omni Jig alignment

[Raven907]

[attachment=1465]I have a Porter Cable Omni Jig dovetail machine.  I use it to cut through dovetails in relatively small boxes.  I am able to set up the guide with half of the fingers at one end to do one pair of joints (corners 1 and 3) and the other half of the fingers at the other end to do the other pair of joints (corners 2 and 4).  I consistently end up with one pair of joints where the boards end up being offset by 1/16" or so.  After assembly, I end up lapping the boxes on a sheet of sandpaper to flush the corners.  The real problem is it is a pain to get the groove for the bottom of the box to line up.  It ends up being a forced fit.  

I have gone to great lengths aligning the stops.  I got the horizontal and vertical legs to line up so that two boards in the top and bottom clamps line up.  But then I realized for through dovetails, that doesn't matter.  It is always sacrificial wood in the top clamps.  My joints should line up since they both reference off the same stop.  I've also checked to make sure my joints are square.  My pins and tails have the same reveal from end to end, so I don't have my boards in the jig crooked or anything.

In the picture, I have not driven the joint home.  It is a little tight and I need to pare it down just a little for a good fit, but you can see what I mean by looking at the top edge of the corner.

[attachment=1465]

Has anyone else fought this battle and won?

Thanks.

[JGrout]

The way I win:

I cut the grooves first in all the pieces then I register all the parts off the groove using a double stick tape to hold it in place 

then I do not care if the joints are off as they register off the grooves

disclaimer: I have no idea if it will work on a PC jig but I do not see why not

[ridgeline]

Do you have the new model omnijig or the old one? The adjustments are different.