Lets you go from a 4 inch blast gate in your dust collection system to a 3 inch hose in 1 step.
I've added a small groove around the 3 inch end to help hold the flex hose in place under a hose clamp. No hose slipping off.
I have made two variations to allow for different sizes of hoses:
YadapClapet4poEx_par_3po-1. Stl has a diametre of slightly less than 3".
YadapClapet4poEx 3po1a. stl has a diametre of slightly more than 3". I find this size fits perfectly with the gray flex hose I have.
I applied acetone and used ABS to strengthen the part to be used in a workshop environment. As it is being formed, if using PLA make sure the layers are bonding.