Saw apparatus including an elongate power-driven saw arbor and a circular saw-supporting collar encircling the arbor and axially slidable thereon. The collar is moved axially on the arbor to shift the position of the saw by an elongate compression-transmitting shifter bar received in a peripheral channel in the arbor. A detent plate is attached to the shifter bar. The plate rides in an interior portion of the arbor channel of greater width than the main portion thereof, so it can restrain centrifugal force-induced radial motion of the shifter bar with respect to the arbor during rotation thereof. The shifter bar is of generally rectangular cross-section, and has radially extending recesses therein. The bar is connected to a shifter mechanism by a shoulder bolt, the shoulder of which is received in complementary cylindrical recesses in one end of the shifter bar and in a sleeve in the shifter mechanism, whereby the bolt permits no axial or circumferential movement between bar and shifter mechanism. The opposite end of the shifter bar is received in a slot extending between opposed faces of the saw-supporting collar. This end also includes a pair of detents, one each being disposed at each end of the slot, whereby this end of the shifter bar is connected to the saw-supporting collar with no axial or circumferential movement possible therebetween. The saw-supporting collar includes an annular portion which supports the saw at the precise axial midpoint thereof.