I think a lot of commercial PCB machines use an air operatedn spring loaded "pressure foot", no balls, but a short brush dust shoe which also connects to a vac to remove chips,dust etc. My Wessel machine built in 1985 had this system, but I removed it when converting the machine as I like to see the cutter and work when cutting. Another disadvantage for me was that as I made miniatures, tiny components not tabbed in were likely to disappear into the vac bag!!! G.