If you have left over in the middle, your fence is either too close or too far from the blade. Move it in or out a bit, then use a test piece exactly the same as your workpiece.
I see you are using the pass, flip, pass method to ensure centered grooves. I like this. It's super easy, no measuring.
Since the panel is 0.125, and your blade is 0.098, you just need the fence a bit to the right or left of centering the groove.
I like to mark a line in the center of my test piece, center that with the blade, run two passes, then move the fence just a hair until the panel fits. Remember that when doing the pass, flip, pass method, moving the fence gets you double
Last edited by sanchez; 11-21-2017 at 07:48 PM.