TIP: As you cut the pieces, check them by laying them
down in place on the paper template (Figure B).
3d. Deburr all the marble holes and use a knife
or file to make a chamfer on the topside of each
(Figure C, previous page). Cutting against the grain
will splinter the wood, so each hole requires a
separate cut for each quadrant.
4. Assemble the front.
4a. In the backboard, drill the e" pilot holes for the
toggle pivot nails. Above them, drill the holes for the
toggle reset nails — two ¼" holes next to each other
— then use a small saw or file to join the 2 holes,
making an oblong shape. Drill and cut another
oblong aperture for the stop screw at the left end of
the result slider.
4b. It’s time to start gluing pieces to the backboard.
First, glue down the input slider holder and bottom
rail. Let the glue dry.
4c. Working from one side, glue down sets of
2 uprights and 1 horizontal for each bit position
4d. Glue down the input holder and result slider
support blocks (Figure E). To make sure the sliders
have enough room to slide comfortably, cut slider-sized spacers out of thin cardboard and sandwich
them in with the sliders as you position the new
pieces for gluing. Make sure the sliders remain
4e. Glue down the clear ramp. (So marbles wouldn’t
fall off my extension to the clear ramp, I added a
back piece there, which isn’t in the template.)
4f. (Optional) For aesthetics as much as anything,
I glued beveled blocks at either end of the input
holder and between the bottom rail and result
holder. I also added small blocks between each
result holder hole. These are not in the template.
4g. Attach the toggles. Nail the pivot nails into the
back panels, threaded through the toggles with a
small washer underneath. Turn the assembly over
and nail the reset nails through the elongated holes
into the other side of each toggle so that they protrude about 6mm.
5. Add the release mechanism
5a. Screw a 1½" #6 wood screw into the bottom
slider, through its oblong hole in the backboard of
5b. Make the diagonal slider. It’s best to size this to
your machine’s actual dimensions, rather than from
plans. Tilt all the toggles to the 1 position (right in
84 Make: Volume 20