The tool used for this purpose is a kind of plane called a plow. Its mode of action will be understood after an examination of the accompanying Figure and of the tool itself.

The iron d, Fig. 80, cuts the groove. The "fence" b determines the distance of the groove from the face of the piece. It can be set at any distance from the iron by means of the screws c. The stop a, which can be raised or lowered by the screw e, regulates the depth of the cut. For this exercise it must be set at 1/2", and the fence must be set so that the groove shall be 1/2" from the face of the frame. Before venturing to use the plow on your frame, you should try it on a waste-piece, and assure yourself that you can cut a smooth, clean groove at the proper distance from the face of the frame and to the required depth. The plow has an assortment of irons, or "bits," of different sizes for cutting grooves of different widths. For this exercise the 3/8" iron will be used. Remember that the plow is to be placed against the front surface of each piece. If this precaution is neglected, the grooves in the several pieces will probably not match at the corners, and the panel cannot be got in. The grooves must not be planed beyond the depth indicated, for if cut too deep they will weaken the pieces too much. The grooves being cut, the studs which have been left to fill them will go into their places, and all the joints should fit quite close. If too much wood has been left anywhere it may be carefully pared away; if too much has been cut off there is no remedy.

Fig. 80.

Exercise 38. Grooving

To prepare the panel, first plane it to the proper thickness, and finish it with the smoothing-plane. Then plane two edges straight and perpendicular to each other, being careful, in planing the end, to avoid splintering, as directed in Lesson XIX (Finishing A Dove-Tailed Box)., page 188. Then cut the piece to the proper length and breadth, remembering that these are not the length and breadth of the inside of the panel, but 1" more, on account of the depth of the groove.

The panel is next to be fitted to the groove by chamfering. Mark the width of the chamfer (1") all round the face with a lead-pencil, or very lightly with the gauge, and the depth (1/4") on the edge in the same way. Lay the piece on the bench, its edge being just even with the edge of the bench, fasten it down with a hand-screw, and plane the chamfer carefully to the mark all round, again being careful to avoid splintering. If this is properly done, the panel will have a thickness of §" at a distance of half an inch from the edge, and will just fit in the groove as shown in Fig. 81. In this Figure, the shading, which has been introduced once before in Fig. 63, c, indicates a cross-section, fine ruled lines being generally used for metal, and somewhat coarser free-hand lines for wood. Do not drive the panel in if it fits tight, but ease it carefully till it enters freely without looseness. The flat side is to be turned towards the front of the frame.

The frame of the door has been made thicker than it ought to be, in order to lessen the risk of splitting the stiles while making the mortises. It may now be taken apart and finished to a proper thickness. This is not the course that a skilled workman would take, nor that which you will follow hereafter in such cases. Setting your gauge at 1/4," make a mark on both edges of each piece at that distance from the front. Then, setting it at 1 5/16," make a second mark at this distance from the front. Plane the faces exactly to these marks. The thickness of the frame will then be reduced to 1 1/16," and the groove will be 1/4," from the front, and 5/16" from the back, the latter distance being left larger because the chamfer brings the back surface of the panel nearer to the surface of the frame than the front, as shown in Fig. 81.

Exercise 39. Fitting a panel.

Fig. 81.