Hoses and dustports come in so many different diameters that you can go crazy trying to match them up.
Sometimes, you can find a hose or adapter that will fit inside a dustport, but its smaller diameter reduces airflow. To maximize airflow, it’s better to fit a hose to the outside of the dustport. For that hookup, you’ll have to customize. Here’s an example.
My shop vacuum’s hose is about 1/4″ larger than my miter saw’s dust port. To make an adapter, I measured the inside diameter of the hose, set a compass to this size and drew a circle on a 3/4″ piece of plywood. Next, I measured the outside diameter of the dustport. Using a Forstner bit about this size, I drilled a hole in the center of the circle. Then I cut out the circle on the bandsaw, making a ring.
Well, the ring didn’t quite fit the dustport. Its hole was a bit too large, so I cut the ring in half and sanded a little off the ends of each piece. I also wrapped a layer or two of duct tape around the dustport to slightly increase its diameter. Eventually, I got a tight fit, with hairline spaces between the ends of the ring segments.
Next, I made the ring fit tight inside the vac hose. It was close, but a bit too small. To reduce the hose’s diameter, I cut two slots in it on the bandsaw. Compressing the hose and ring with a hose clamp produced a perfectly tight fit. Unlike a taped connection, this one won’t come loose! –Tom Caspar