Sizing your CA finish

I've been thinking about this since talking to Dai Sensei. Is there any method that you use to ensure that when you put the finish on, you end up with a diameter that matches the pen kit, instead of being slightly larger? So to explain a bit further, you trim your pen blanks a fraction smaller than the bushings, build up with CA and then sand/polish the CA so that it's all flush with the pen parts. Calipers are a big help here but do you shoot for eg 0.1mm of CA or is it more a guesstimate of how much you need? You need to be fairly precise with matching the pen parts as you can generally feel even a couple of thousandths out so you've got to be pretty close with your sizing.