A couple of days ago, I made three more ribs for a total of eight for the largest portion of the bass horn, the mouth flare. Then I purchased a new sheet of AC plywood, 19/32" thick. When I built the first one, I was not sure how it would work out so I used old pieces of plywood and paneling found at the dump. The recycled plywood pieces were warped. I had to reinforce the plywood flanges with pine cleats to try to correct the warping. Parts of the plywood were damaged and could not be used. The second time around, I decided to use new plywood for the flanges. The first two flanges I cut for the mouth flare are perfectly flat so I don't think I'll need the pine cleats. As a result of having no cleats, I was able to use shorter sheetrock screws to fasten the ribs to the flanges. Here is the mouth flare assembled.
|Second Sound Transformer Bass Horn Mouth Flare Flanges And Ribs|
|Sound Transformer Mouth Flare Showing Rib Curves|
|More Clearance Between Rib Ends To Secure The Trapezoidal Side Edges|
For paneling, I selected a Masonite board with hard finish on one side. The thickness is about 5/32". Here is the panel with a yard stick as a straight edge clamped for marking out the trapezoid.
|Marking The Trapezoid On The Masonite Panel With A Yard Stick|