The plans here show how my solar dryer is supported on a half-inch thick plywood base. You could use thinner or thicker sheet material here, depending on what you’ve got, but 1/2” is a good compromise between strength and weight. Don’t go thinner than 3/8”
Step#2: Build the Base Frame
Cut and fasten two 1 1/2” x 3” base side strips to the top face of the plywood, so the side strips match the width of the completed collector frame you built before. Later on, fasten 2 1/2”-wide butt hinges to the bottom ends of these strips and the bottom edge of the collector frame. For now, fasten two base blocks to the plywood base, one tight to the edge of each base strip, as shown on the plans. These base blocks do two things: they provide full support for the hinges; they also prevent the screen frames from sliding down and out of the dryer.
Make sure the base side strips are parallel to each other, then scrounge some old metal roofing material for the space between side strips. The colour of this roofing material doesn’t matter much. The only purpose of the metal is to create an open airspace underneath the screen frames that you’ll build later. All that matters now is that the roofing material have ribs that are 1/2” to 3/4” high. Spacing of ribs isn’t critical. The purpose of these ribs is to raise the drying rack so air can flow underneath. That’s all.
VIDEO – How to Build the Base Frame
With the base frame done, now it’s time to move on to build the drying frames.
Step#3: Build the Drying Frames
The heart of the drying frames are the screens, and people use several different materials for building their own solar food dryers. Window screen is one of the most common options because it’s cheap and you can buy it anywhere. The main problem is that it’s not exactly a food grade material. Far from it. Fiberglass window screen is especially plentiful and cheap, but there’s no way any commercial food inspector would let it touch anything meant for human consumption. The main danger is the possibility of hormone-mimicking chemicals that may be present on synthetic materials like fiberglass. So, what about aluminum window screen? This is probably safer than fiberglass, but there still is the very real danger of aluminum leaching into foods that you dry. This is especially likely with acidic foods such as tomatoes. High aluminum levels have been identified in the brains of Alzheimer’s patients, so there certainly reason for concern.
All of these issues are why I like food-grade, stainless steel mesh for drying frames. It’s strong, safe, highly corrosion resistant and you only ever need to buy it once. Google “stainless steel food mesh” and you’ll find lots of suppliers that deliver across North America.