Toilet Flapper (Single Piece)

This is a toilet flapper for 2" flush valves (50mm, ~size of a baseball).  It has a much simpler shape than injection molded flush valves because we can get some benefits from 3D printing.  See below if you're curious why this design works.  When you print this keep it light and print it on a smooth-ish build plate.

How to Print?
Material: TPU 95 shore
Build Plate: Smooth or rough with Kapton (PEI) tape (see pictures)
Top/Bottom shell: 3 layers
Wall Loops: 3 layers
Infill: 10% grid
Supports: None

Important Dimensions
Radius: 71 mm (2.79 inches)
Distance between wings: 42mm (1.65 inches)
Hole for Chain: 5mm
Holes in wing (hinge): 10mm
 

Why doesn't it look like the flapper on my toilet?
One of the major reasons the flapper on your toilet has an intricate ball shape on the bottom, is because it needs to float.  With injection molding it's hard to add something like sparse infill to make a part light; this is a problem because the TPE the flapper is made of has a density similar to water.  The design instead includes a bowl which traps an air bubble to provide buoyancy.  This is why you don't have to keep holding the lever down, you press it and walk away.  The flapper floats up until the water level drops and then it closes.  Once it closes, any water that ended up filling that bowl on the bottom of the flapper drains out.

We don't need something that complicated because we are 3D printing.  We just print a shape to seal the flush valve opening and then make the flapper light using sparse infill.  When printed as described this flapper has an apparent density of ~0.5 g/mL (water is 1.0), so it easily floats.

Welcome to the future.

Can you keep talking to me about flappers?
Another reason why flappers have that shape, is when using soft rubber it helps the flapper line up and seat with the drain opening.  The rubber is so soft that it can distort when you pull the flush handle and not come back to fully cover the opening, causing a leak.  When printing with TPU the wings/hinge part are stiff enough alignment isn't a problem.  

Can it really seal?
Yes, I haven't had problems with leaks when printed on a smooth build plate.  While not as soft as the rubber used in commercial flappers, if we print TPU with a smooth bottom and very little infill (to give it some flex) sealing isn't an issue.   If you do have problems with leaks, please check that the drain opening is clean and has no deposits or mold on it.  If that's not the case and the the print seems to be of good quality, check that everything is lined up.  This flapper was designed to be generic, but like snowflakes, all toilets are unique.  You just have a very special one which unfortunately doesn't work with my design.