I posted this on TH1, so having found the pictures I am going to post some of my old stuff again, might be of use to some one.
I bought a SIP bobbing sander, which has a dust port but the collection from it was hit and miss.
078 by DaveL_, on Flickr
the main reason it the wide open side
079 by DaveL_, on Flickr
so with a few bits of ply and bit of batten I made this
080 by DaveL_, on Flickr
which just slots in under the table
081 by DaveL_, on Flickr
thus directing more of the suck to the holes around the spindle.
It can only be used with the table square to the spindle but that is most of the time for me.