you want.
Take the two half bricks and looking at the coil layout, route the bricks so the heating elements will fit.
The routed width should be slightly under the outside diameter of the Nichrome coil and sufficiently deep
to contain the coil below the surface of the brick. The heating coil placement in the furnace is not critical,
but it should be close to the place shown in the drawings.
THE DOOR
The door and back brick must also be routed to a depth of 3 inch along all four sides so part of the brick
protrudes into the oven openings for better heat retention. This also can be done on a drill press using a
flat-ended bit as a router or by carefully cutting and scraping away the excess material with a knife.
Refer to the brick and coil drawing for the width of these cuts.
If you have a drill press or milling machine, the routing can be done by simply using a drill or router bit of
the required diameter. We can carefully outline the coil layout on the brick in a soft pencil, the drill or
router bit set to the required depth, and the brick pushed into the revolving bit, following the pencil
outline. If you do not have a drill press, the routing can be done with a piece of round steel stock by
pressing the end of the steel into the brick and using die rod as a scraper. This may seem difficult, but
the brick is relatively soft and can be cut easily.
Setting up the heating coil is next. Cut the coil exactly in half, this can be done by simply counting the
number of coil loops and cutting it at the midpoint. At both ends of each coil half, If the coil must be
straightened by stretching the coil loops out, so there is a 4-inch length of straight wire.
We will fasten the straightened ends to the terminal screws at the back of the oven. About 6 to 8
straightened coils are sufficient to produce the above length. The total length of the routing should now
be determined and each coil stretched about one inch short of this length. Lay a yardstick on a flat
tabletop, grasp both ends of one coil and stretch the coil using the yardstick as a guide.