When dovetailing with the D4 jig, I see lots of references to backer boards to reduce tear out. What material do you use for the backer board, and how thick should it be? I tried poplar that was 5/8 thick and it did not work very well in my novice opinion. If a person uses a backer and a fronter board to prevent tear out on both sides of the dovetail -- it gets awful thick. So, what does a person use to get those fantastic cuts shown by our craftsmen posting on the creek?