sorry my post was a bit of a mix up to much red me thinks
i have made an extraction pipe under the bench then ran a single 1 1/2 " pipe from the 4" pipe to a band saw then split that with another 1 1/2" pipe to the top(blade) on the same run i have a drill which i also want to extract from pipe has end stop not sure how to go further.
it's a small bench top 8" delta the base has a 1 1/2" outlet, would i be better to blank that of and try to fix 4" under table with the end of the pipe reduced to create a slot ,do you think would be any use.
the drill is also a bench top any advice for extraction?
You are going to kill the extraction by using such small pipes and trying extract from more than one machine at a time. You need blast gates to blank off the ports to machines you are not using.
If you must restrict diameter, do it for the absolute minimum run.
You already have two replies about drill extraction