The DD does not do small bits all that well. The 2 main adjustments are the cut depth (the stop) and how the bit is positioned in the holder.
Getting the latter set with the bit in the holder. Have bit, loose enough to let the gripper pull the bit to the stop & set the position.
As it is held tighten the bit holder. I made that mistake in the beginning, once pointed out, success was at hand.
What are you doing buying you are supposed to be making room for old cars ......... LOL
Pep