My miter saw sees a lot of use. Consequently the amount of sawdust it creates is overwhelming and it goes everywhere. To help get some control over this problem, I built the sliding dust port you see below. The key component in this system is the large dust port. It’s mounted to a plywood frame that slides in grooves in the surrounding frame’s rails. This way, you can move the port to catch the sawdust when mitering.
The drawings show how it’s all put together. The assembly is designed to bolt or clamp to the back of the miter saw station. It can be modified to suit your particular setup. I started the construction by making the outside support frame.
Grooves in the top and bottom pieces house a plywood dust port frame, as shown in details ‘a’ and ‘c.’ After assembling the frame, you can make the plywood frame to fit the dust port.