I needed some air duct valves to control ventilation for several printers. I made some of PeterH1500's ball valves which are really good, but they are too heavy duty for some of my uses.

I needed a lightweight valve that was cheap to make so I created this simple butterfly valve. This is just a prototype but it worked well enough that I thought I'd share it. One unique feature is that this valve can be scaled (50mm and 100mm shown) without any modifications.

My printer ventilation system uses 100mm laundry ducting and a heavy duty 120mm fan. These parts were made with eSUN PLA-ST. The valve seal is good, but not perfect - this works fine for printer ventilation since all the printers have a very small amount of ventilation at all times.

Print 2 valve bodies and 1 butterfly valve. The butterfly valve should be printed with the top face of the handle flat on the build plate. The hole is undersized so you will need to shave a bit off the hole or the axle to adjust the fit - the axle should be snug and the faces of the valve bodies should be flat.

Hardware needed: 4x m3x12 bolts, nuts and washers.