Any blast gun without a trigger is a good one to me! I hate holding the trigger while blasting. Foot pedal or foot switch solenoid is much better IMO. By not having to hold the trigger, the gun can be turned and twisted for weird angles more readily. My gun has the capability to change out air jet sizes, as well as the nozzle size, and the air jet can be adjusted back and forth relative to the nozzle to adjust venturi effect. I guess if a guy was creative, he could measure and adjust the suction of the gun while air was being applied, using a manometer or possibly a vacuum gauge. I might have to give this a try.
A major factor is the introduction of inlet air mixed with media in the right proportions. The cabinet design has much to do with this. If a tube is extended down into a batch of media, it will tend to get an uneven flow of abrasive to the gun. The use of a hopper bottom with a media outlet underneath, along with an outside air inlet will tend to smooth things out.
There is usually a 90 degree pipe fitting with a hole drilled into the side of it under the cabinet hopper. The suction hose is inserted into this fitting and adjusted in or out to expose more or less inlet air, and held in place with a thumb screw tapped into the side of the fitting. This allows you to adjust the ratio of inlet air to media flow. All this applies only to suction type cabinets, pressure cabinets are a different animal.
Edit: Found an old picture of my media port. The suction hose slips inside this fitting, and is adjusted in or out to expose the hole to outside air, to adjust the air/media mix. The smaller fitting was where I experimented with an air jet inside the fitting to see if it helped the flow of media. That's been so long ago that I don't remember the results.
It's called heater hose. Easily obtainable at any auto parts store.
