Fig. 1615.
[Fig. 1615] represents the arrangement of square holes and T-grooves employed upon large planers. The square holes are cast in the table, and are slightly tapered to receive taper plugs or stops against which the work may abut, or which may be used to wedge against, as will be hereafter described, one of these stops being shown at s in the figure.
Fig. 1616.
The T-shaped slots f, g, h, are to receive the heads of bolts as shown in [Fig. 1616]. The bolt head is rounded at corners a, b, and the square under the head has the corresponding diagonal corners as c also rounded, so that the width of the head being slightly less than that of the slot it may be passed down in the slot and then given a quarter revolution in the direction of the arrow, causing the wings of the head to pass under the recess of the T-groove, as shown in [Fig. 1617], which is a sectional end view of the groove with the bolt in place. The square corners at e and at f prevent the bolt from turning round more than the quarter revolution when screwing up the bolt nut, and when the nut is loosened a turn the bolt can be rotated a quarter revolution and lifted out of the groove.
Fig. 1617.
Now it is obvious that these slots serve the same purpose as the longitudinal T-grooves, since they receive the bolt heads, and it might therefore appear that they could be dispensed with, but it is a great convenience to be able to adjust the position of the bolt across the table width, which cannot be done if longitudinal grooves only are employed. Indeed, it might easily occur that the longitudinal grooves be covered by the work when the short transverse ones would serve to advantage, and in the wide range of work that large planers generally perform, it is desirable to give every means for disposing the bolts about the table to suit the size and shape of the work.