I have a ceiling mounted central a/c Aluminum cold air return that I would like to cover during the winter months. The outside dimensions are 26" X 38". The outer frame is 1 1/4" wide and 1/8" thick. There are some predrilled holes in the frame which have a diameter between 11/64" and 3/16". The cover that I have made has a wood frame with plexiglass in the center. My plan is to drill holes through the wood frame that align with the holes in aluminum frame. I did a test with a #10 self tapping sheet metal screw. The problem was that the screw would bite and hold but if I removed and then reinserted the screw it would not hold. I assume that if I tap it then I can use a machine screw which can be installed and removed every year.
Cut tap or Forming tap? What size tap? What size screw.
Note: the aluminum frame is tight to the finished sheet rock ceiling.
Thank You.
Cut tap or Forming tap? What size tap? What size screw.
Note: the aluminum frame is tight to the finished sheet rock ceiling.
Thank You.