Here's my technique on getting a straight line stitch using an edge grooving tool & the Craftool Over-stitch Wheel System

Item #8091-00 from Tandy. This tool comes with 3 wheels that are easy to change over , you get 5,6 & 7 TPI.

1 - Set your grooving tool to the desired distance & cut your groove, do several passes to get the depth you require.

2 - Wet your stitch line, position your over-stitch wheel in the groove & keeping a firm pressure move slowly forward and then back, repeat and progressively move along your groove.

3 - The result is a perfect formed straight stitching groove with even indents to take the awl.

4/5 - Take your awl & here i am using bees was to stab the hole at approx 45 degree to the stitch line.

Source: First Piece