John,
I just finished replacing the interior doors in my house using the same size hinges as you are. I used a 3/4" (.750) OD guide bushing and a 1/2" mortising bit with a simple homemade template to mortise all the hinges.
To make the template I just traced the outline of the hinge on a piece of mdf and then offset that trace line by 1/8" (.125) all the way around the perimeter of the hinge to account for the guide bushing to cutter offset and then I cut along the offset line with a jig saw. I was installing new doors in the old existing jambs so I just measured the depth of the hinge mortises from the door face in the old doors and added the 1/8" offset. I used this measurement to install a fence made from a scrap piece of 1x2 pine to the mdf template. I made the fence long enough to extend a couple of inches from each end of the template to allow me to clamp the jig to the door.
To use the jig I just transfered the hinge locations from the old doors to the new doors and then used a piece of 1/8" stock to position the cutout in the template to the layout lines and clamped it in place, set the cutter depth to the hinge thickness and cut it out. You should try the template out on a piece of scrap or one of the old doors first to make sure you get a good fit. The mdf is easy to work with so if you need to make adjustments you can just use a file or sandpaper.
Greg |