The feeds are put into or thrown out of action as follows:—On the same shaft or pin as the pawls g and f, is secured a tongue t, [Fig. 1599], whose end is wedge shaped and has a correspondingly shaped seat in a plate v, whose cylindrical stem passes into a recess provided in d, and is surrounded by a spiral spring which acts to force v outwards from the recess.
In the position shown in the figure the end of t is seated in the groove in v, and the pressure of the spring acts to hold t still and keep the pawl g from engaging with the teeth of gear-wheel h. But suppose the handle w (which is fast on the pawl g) is pulled upwards, and t will move downwards, disengaging from the groove in v, and the upper end of pawl g will engage with the teeth of h, actuating in the direction of the arrow during the upward motion of rod a, and thus actuating pinion n and putting the vertical feed in motion in one direction. When the rod a makes its downward stroke the pawl g will slip over the teeth of h, because there is nothing but the spiral spring to prevent the end of the pawl from slipping over these teeth. To place the vertical feed in action in the other direction, handle w is pressed downwards, causing the bottom end x of the pawl to engage with the teeth of h.
Planer Beds and Tables.—The general forms of the beds of small planers are such as in [Figs. 1557] and [1558], and those of the larger sizes such as shown in [Fig. 1563].
It is of the first importance that the V-guideways in these beds should be straight and true, and that the corresponding guides on the planer table should fit accurately to those in the bed; for which purpose it is necessary, if the greatest attainable accuracy is to be had, that the guideways in the bed first be made correct, and those on the table then fitted, using the bed to test them by.
The angle of these guides and guideways ranges from about 60° in the smallest sizes to about 110° in the largest sizes of planers. Whatever the angle may be, however, it is essential that all the angles be exactly equal, in order that the fit of the table may not be destroyed by the wear.
In addition to this, however, it is important that each side of the guides stand at an equal height, or otherwise the table will not fit, notwithstanding that all the angles may be equal.
Fig. 1600.