Cutting and assembly

Figure 5.
Left-side panel, showing cleats laid out on the inside surface prior to fastening with screws.
  Figure 6.
Layout of socket locations and wiring plan (bottom view).

Figure 4.
Cutting plan to obtain the necessary plywood parts with a minimum of saw cuts.

The cutting diagram in figure 4 shows how you can obtain all of the ½-inch plywood pieces from the single 4 x 8-foot plywood sheet. It is usually most satisfactory to measure from the factory cut edges as shown. Be sure to allow room for the saw kerfs between adjacent pieces.

1. Cut the plywood sections to size using either a table saw or a skilsaw with a guide. I was able to get reasonable results using a skilsaw with no guide (and then some a posteriori spackle), but it will be far easier to achieve a box that leaks less heat out the back with perfectly straight cuts.
2. Cut the 1 x 1-inch wood strips into the lengths shown in figures 2 and 3. These pieces will be used to hold the box together, for tray-support cleats, and for the tray frames. Before cutting the tray-support cleats to their final size, I drew the correct positions on the left and right side panels, placed the cleat over the drawing, and marked exactly where the cut should be. Figure 5 illustrates the drawing/layout procedure for the tray-cleats.
3. Next, lay out the porcelain sockets, and fasten them to the base, as shown in figure 6. Fasten the wire to the porcelain sockets.
4. Connect the wire that goes to the yellow screws on the sockets to the thermostat, mounted near the rear on the left side panel. The yellow screws on the socket connect to the center pole, rather than the threaded wall of the socket.
5. Connect the wire that goes to the white screws to the white wire in the extension cord (see figure 6).
6. Connect the ground wire (green) in the extension cord either to the ground wire coming from the fan motor (as in figure 6), or directly to the junction box.
Figure 8.
Fan mounted onto bulkhead via "tabs" made with tin-snips.
Figure 7.
Assembly of front, left-side, and base.
7. Next, fasten the left side panel and front panel to the base (figure 7).
8. If you're using a duct-type fan, which I recommend, cut the necessary hole in the bulkhead (about 8 ½ inches in diameter for an 8-inch fan; about 6 ½ inches in diameter for a 6-inch fan), and fasten directly to the bulkhead. The 6-inch duct fan I bought from Home Depot (not a personal endorsement) did not have an obvious mounting mechamism to attach to the bulkhead, so I used tin-snips to cut out mounting tabs (see figure 8).
9. Now set the bulkhead in place (5 to 5 1⁄2 inches from the front panel, as in figure 3), and fasten it temporarily in position by two screws through the left side panel.
10. Center the 1 ½-inch-diameter air vent hole in the front panel, directly in front of the fan motor, about 1 inch away from the motor. This will allow the relatively cool room temperature air to pass over the motor and cool it.
11. Next, fasten the right side, back, and top in place.
12. Enclose the heat shield in heavy-duty household aluminum wrap. This provides a reflective surface to protect the plywood heat shield. It also provides a smooth surface on the top of the shield for easier removal of juices that may drip from the drying trays.
Figure 10.
L-bracket used to re-inforce corners of drying trays.
Figure 9.
Completed drying tray, assembled from ¾ x ¾-inch wood pieces and 1 mm mesh nylon screen.
13. To build drying trays like that shown in figure 9, I used 1 x 1-inch nominal (3⁄4 x 3⁄4-inch actual) pieces of wood, cut to the lengths indicated in figures 2 and 3. Use L-brackets to re-inforce the corners of the trays and prevent twisting of the wood pieces (figure 10). Lay the 1 mm mesh nylon screen over the finished tray frame, and cut the screen around the tray frame, adding 11⁄2 to 2-inches of screen to the overall dimensions.
14. Staple the screen to one side of the tray frame using ¼-inch staples, then staple the opposing side after pulling the screen tight. Staple the remaining two sides in a similar fashion. Pull the screen as tight as is practical, as the weight of the fresh fruit will cause some sagging. Finally, trim the excess screen using scissors or a razor knife. It is possible that metal screen would be a better alternative to nylon, as metal screen would likely sag less.
15. You'll need some type of adjustable latch to hold the door in a partially opened position during the initial stages of drying, when the moisture is being removed rapidly. I used a small length of chain and a hook, but a standard ball-link chain with a catch would also work.
16. As a check on your thermostat setting, you should have a thermometer capable of reading within the range of 100–160 °F. A kitchen-type meat thermometer works nicely.