Some large commercial tables have a central exhaust duct down the side or up the centre and as the torch passes into a zone, a gate opens and the others close (usually by pneumatics) so the draft is centralised in that particular cutting zone. It is possible to track the torch position and activate the relevant zone with LinuxCNC. The dust is usually filtered and the exchaust ducted outside of the building. I did write a component that did this for another user which triggered a bank of air solenoids.
Rod, you catched me, thanks for this heads up. I have not even thought about that problem of exhaust gases and
pollution stuff. I was thinking to make a water based table under the torch, but this solves just partly this
problem of gases. We have a luck of being in a country where its hot the whole year so everything is open and ventilated, but that does not mean I dont need it.
