First step in making an excavation for the film holder is laying out the recess. To do this, I center the film holder’s window over that of the insert and strike a line:
When the area is marked, I turn to the router and a rabbeting bit. I size the bearing to be just a little larger than the marked line so the holder isn’t too tight in the back. Then I rout the recess. The recess needs to be a little longer on the end, and open on the front. I rout these areas free-hand using a hinge mortising bit. The edges and round corners are finished using a chisel:
A quick check shows we’re on the right track:
The film holders have a double light trap on the darkslide end:
To Make the excavations for the light trap, I use a Dremel with a router base and round burr cutter, and rout the open end of the insert free-hand with the router and hinge mortising bit. The edges are again clean up with a chisel.
A final check shows the light trap is a perfect fit in the new insert:
The next step is to build the ground glass holder. This is a delicate project, as the pieces are on the order of 5/16″ thick, and the rebate for the ground glass has to be placed at the film plane. I’ll start by planing my cherry this afternoon…