Cutter Heads with Circular Cutters

This form of cutter head was invented by S. J. Shimer, and are generally known as Shimer cutter heads. The principle of construction is shown in Fig. 3204, which is for an ogee door pattern.

The cutters are circular in form and are seated at an angle to the flange to which they are bolted, this angle giving side clearance to the cutting edges.

The full amount of cut is taken in successive stages or increments; thus in the figure, the two upper cutters would produce one half the moulding, and the two lower ones the lower half. As the cutters are sharpened by grinding the front face, therefore they will maintain correct shape until they are worn out. Fig. 3205 represents a Shimer head for producing the tongue, and Fig. 3206 a similar head for producing the groove of matched boards.

Fig. 3207 shows the action of the groove head, the cutter or bit d being shown in full lines and the second cutter being shown in dotted lines. Cutter d, it will be seen, operates on one half of the groove, and cutter c on the other half, each cutter having side clearance, because of being seated on a seat whose plane is not at a right angle to the axis of revolution of the head.

By thus taking the cut in detail, the head works steadily, while the side clearance makes the cutters cut clean and clear.