Air valve adjustment on H&S Evolution

[sergant-san]

Is there any way to adjust the air-valve on my airbrush so the movement from off to 100% air is more than 2mm?

[cmatthewbacon]

Unless I misunderstood the question, you don't control the airflow with the trigger. Press down to turn the air on, pull back for more and more paint flow.

 

To control the airflow, you adjust the output on your compressor to change the air pressure, usually between 8-10 PSI and around 25 or so (the amount of airflow through any given brush increases with higher PSI, but different brushes give quite different amounts of airflow through the brush for the same compressor pressure). An alternative is what they call a "MAC valve" (Micro Air Control, I think),  which is sometimes a feature of the brush, but more often is an inline fitting between the air hose and the brush itself. It's just a barrel, with a screw in the side which you turn to throttle back the airflow.

 

If you're using canned air, you should get a compressor. More seriously, your air pressure will be going up and down all over the place so it's impossible to manage with any kind of valve...

 

best,

M.

[sergant-san]

You can control the airflow with the trigger to an extent, but the trigger travel distance from 0% to 100% air is very small, about 2mm - 3mm on Evolution. The question was, is it possible to increase that trigger travel distance? 

[little-cars]

If you take the quick release tail off the bottom of the air valve there is a flat brass screw.  You will normally see three threads above this at a normal setting.  Try turning the screw out half a turn at a time and see if that helps.

 

Paul

[cmatthewbacon]

What I'm saying is that you're not INTENDED to control the airflow that way, which is why it's not very well optimised. Dunno on an H&S, but if you unscrew the hose on an Iwata, and look into the bottom of the brush, you can see a brass plate with an engraved line across it. That, if you unscrew it completely, releases the air valve components for cleaning. If you back it out a little way, you can soften the spring pressure, and, by accident get a little more travel. But it's really only intended as a way of fine tuning the trigger "action" pressure. As you say, the difference between 0 and 100% is such a small distance that reliably and consistently achieving 40% or 75% would be a nightmare.

 

What effect are you trying to achieve by varying the air pressure using the trigger? Typically, you set a fixed air pressure based on the viscosity and volatility of your paint and the distance you want to spray from, to whatever you need to get good atomisation (no "speckling") and no drying before the paint hits the surface. Everything else is done by varying the distance between the brush nozzle and the workpiece and the amount of paint flow. In 20 years of airbrushing everything from mottle and squiggle camo on 1/72 German aircraft to high gloss 2K clear coat on a model car, I've never modulated the air pressure with the trigger...

 

best,

M.

 

 

Edited July 28, 2017 by cmatthewbacon

[sergant-san]

2 hours ago, little-cars said:

If you take the quick release tail off the bottom of the air valve there is a flat brass screw.  You will normally see three threads above this at a normal setting.  Try turning the screw out half a turn at a time and see if that helps.

 

Paul

 

thanks Paul, 3/4 of a turn gave me another .5 mm play which is more comfortable. 

[LaurieS]

5 minutes ago, sergant-san said:

 

thanks Paul, 3/4 of a turn gave me another .5 mm play which is more comfortable. 

 

0.5mm of what play. I am intrigued ie what has been altered and what is the effect.

 

I am not sure why any alteration is required when the airbrush and air valve gives full control

over pressure and amount of paint to be released.

 

Laurie

 

 

[sergant-san]

+0.5mm of up/down movement on the trigger..