If you are a do-it-yourselfer and you want to make your own hay bailer, you don't need to be a mechanical engineer. Though most hay bailers are now tractor-like heavy machinery, it is still possible to make hay bales using old fashioned technology. This is where a simple, plywood hay bailer comes into place. A bit of plywood and some wood cutting utensils and you'll have your own homemade hay bailer in no time.
Cut two 18-inch by 14-inch rectangles, one 37-inch by 18-inch rectangle and two 37-inch by 14-inch rectangles from a single 4-feet by 8-feet by ¼-inch plywood board. Use a table saw to cut the plywood.
Cut Two 1-inch notches onto one 18-inch long side of each of the 18-inch by 14-inch rectangles using a ½-inch wide blade on a mitre saw. The notches will then measure 1-inch by ½-inch and should be six inches apart from each 14-inch long side of the rectangle and six inches from each other.
Build a wooden box frame using the two 18-inch by 14-inch and the two 37-inch by 14-inch plywood rectangles so that you have a frame that measures 14-inches in height, 18-inches in depth and 37.5-inches in width. Use staples or ¾-inch screws to attach the corners of the frame. The notches on the 18-inch by 14-inch rectangles should all be facing the same direction on the frame.
Attach the 37-inch by 18-inch rectangle to one side of the frame in the same fashion that you attached the corners of the frame. This will close off the frame into a wooden box. The 37-inch by 18-inch rectangle should be attached to the frame on the side opposite the notches so that the notches are facing towards the open end of the box.
Insert two 75-inch strings into the box so that the strings lay across the bottom of the box and come out of the box through the notches.
Fill the box with hay and then tie the hay into a hay bale using the ends of the strings sticking out through the notches.