I agree with the earlier post about keeping pressure on the outfeed side
as soon as possible. Also, check that your infeed and outfeed fences are
parallel. It not, and you try to keep the leading edge against the
outfeed fence then that could cause your concave cut.

Garry Collins wrote:
I have a router setup similar to that from the Router Workshop with the
infeed side of the fence 3 mm less the outfeed. I aligned the cutting edge
of the bit with the outfeed side of the fence so each pass should take off
3 mm along the entire length of the board. This should give a sound edge-
to-edge join boards. The boards I am using are already dressed and simply
need some edge work to enable a sound glue joint to form.

I keep pressure against the infeed side of the fence until the last 25 mm
or 1" of the board and then move the pressure to the outfeed side of the
fence. The boards are about 400 mm or 17" long. Each of the boards that I
have jointed in this fashion end up with a banana shape in the middle, it
somehow seems that I am taking off more material in the middle of the
boards than at the ends. What am I doing wrong?

Thanks for the help in advance.