experience u201c by eye u201d when viewing the light between the bit 20 and such surface 25 however a user may also simply insert a gauge of appropriate thickness between the bit 20 and such surface 25 while at substantially the same time tightening the set screw 7 in collet 6 also appearing in fig2 is channel 15 in this preferred embodiment extending fore and aft 0 125 inches deep from the front edge of the sub base 10 to the back edge of the sub base 10 the channel is further defined by right channel side 14 and left channel side 17 which are 0 90 inches from each other in this embodiment thereby providing a channel 15 0 90 inches wide and 0 125 inches deep front to back along the lower face 13 of sub base 10 finally in fig2 there appears the front face of front edge 18 of the sub base 10 which is formed in sub base 10 at the time of manufacture to provide a space between bit 20 and the sub base 10 thus front edge 18 is defined by ridges in the outside edge of sub base 10 i e ridge 27 on the right side of the router and ridge 28 on the left side of the router between ridge 27 and ridge 28 the front edge 18 presents a flat face toward the front of the router and the bit 20.