of the knob 92 will cause the threaded portion to be moved inwardly toward the cylindrical mounting portion of the depth guide member to lock the same thus the depth guide member will be locked in place depending upon the amount of force that is applied by rotating the knob 92 it should also be understood that the locking mechanism 90 not only locks the depth guide member in place but also locks the body 70 so that it will not rotate relative to the accessory interface 42 this is achieved by a transfer member 98 which preferably consists of a preferably cylindrical member 98 that fits within an aperture 100 in the body 70 and has a length sufficient so that when the locking mechanism 90 is tightened the transfer member 98 will be brought into contact with the accessory interface 42 to lock the body 70 in place and prohibit it from being rotated an opposite end 102 of the transfer member 98 may be appropriately curved to fit around a portion of the circumference of the cylindrical mounting portion 78 as shown in fig8 the thickness of the body portion 70 is preferably minimized but is slightly larger than the diameter.