[changeoffocus]

day 2

I decided to change the height of my Thien Baffle to 16". Why? Because the HVAC hoods I have seen so far have a rapid structure change from circular to rectangle, I have a 3HP dust collector (which is unknown if a Thien Baffle can even handle a 3HP), and when you step on a 6" spiral duct you can come to 8" high and 4.5" wide oval which should be good enough. 8" x 2 = 16".
While at the Home Depot, I bought hardboard, and 1/2" pipe insulation. I am unsure if using the pipe insulation will function correctly, but heck… for 97 cent worth a shot. I also built the support structure. This week, I'll be getting the 1/16" lexan and ordering the 7" bellmouth (for my 7" chimney inlet to the DC).

Maybe you hid the fact that you cut too far around by placing that hardboard on there. Your 120 to 240 degree openings appear to be OK. Looks like nice workmanship.