have you measured your cutter with mikes? A lot of router bits are not exactly what they should be. You have to be right to size.
cfm said:When using the table and fence as Bob & Rick do, they move the fence to adjust the fit. This gives more or less bit to the wood. If you are using the fixture I am thinking of - when one board is set vertical and the other horizontal, overlapping and butting together - Lowering the bit SLIGHTLY (1/64") will tighten the joints making the cut deeper.
Raising the bit SLIGHTLY (1/64") will loosen the joint making the cut more shallow. I am not too sure that bit size is so important to use a micrometer, as long as it fits into the jig properly without causing damage.
This information is from the Owners Manual for the Craftsman model 315.25790 Dovetail Template. I hope this helps
All the best
cfm