Need a blasting cabinet

Most of the ceramic nozzles have a collar on them,by adjusting gap you can change the performance.
Too small and sand wont all go through, creates a choke point and eventually plugs up and only way to clear it is to block nozzle and blow sand backwards.
RRR suggested i use glass bead instead of sand in my cabinet, best suggestion yet.
Also draw tube needs a source of open air to assist with siphon,helps prevent bridging.