I wanted to hook my table saw up to a shop vac (no, it doesn't do a perfect
job, but gets 75%; and I have neither room nor budget for a dust collector)
but couldn't find an adaptor. So I made one out a PVC pipe fitting from the
plumbing department. Works great and only cost a dollar or so. It didn't
fit perfectly, but a wrap of duct tape took care of that.
Worth a try.