I heard there are some single action airbrushes that u can preset to get consistent lines if u have a good regulator, is this true? Reason I ask is that I'm having a hard time maintianing a cosistent line with my Crescendo 175. I'd like to try panel line shading, but the course precision of the trigger makes it hard to do. Should I consider a good single action?

Try adjusting needle depth of the 175. That (in theory) would convert the double to a single.
A second work around is to put a piece of tape over the top of the brush to control how far back you can pull the trigger.
Just a couple of suggestions.

bebe - sorry you're having trouble with the 175, feel bad that I gave it good marks and you're running into problems.

Oh don't be sorry...its just probably the fact that I don't have alot of experience with airbrushes. Its obvious that its versatile. It just seems that an alternative brush would be one that I can be preset with all variables and shot at will without having to concentrate on finger pressure so much. Any recommendations?

I have got an aztec A470 airbrush.
it's a double action brush, but you can use it as a single action as well ( with good results )
it's great.
also very convenient to change colours while spraying and easy to clean.
a real treat.

I just love my Paasches H ..I can do things with this brush that I could never do with my double action Badger (don't ask me which one it is in the garbage) I think the real trick is more in the paint and thinner mixes that you use ...I usually paint with 25%paint and 75% thinner (can vary a bit depending on what type of paint ) The trick is my nozzel almost closed and making multiple passes before you even see the paint start to show ..Slowly but surly is what I say..

Rick

Well, I went out and got an Aztek 470 after reading so many positive posts about it. Right out the box I was able to create fine lines and I fealt like I had great control over it. There's no doubt that the Badger 175 is built much better, but like I said, I had a hard time operating the trigger consistently to make fine lines. The trigger seems too course and to have to small a travel. I will try an acrylic extender in the Badger to see if that makes any difference.

I have a Paschee H Single Action airbrush and it works excelent for all kind of porpouses.
I have the three diferent types (No. 1 - 3 - 5) of aircup, tip and needle so you can regulate the flow to the kind of mix (paint / thiner) you are using.
For jobs like panel line shading I use the No.1 set, a well diluted paint and a pressure of about 30-35 psi.
I love this airbrush, its cheap, strong and very ease to clean, I strongly recomend it.

just did a lot of pre shading 10 min. ago with my aztec 470
I can't adjust the pressure on my compressor, but It was very easy doing so by controling the trigger movement on the airbrush.
For preshading I use relativly thick paint with little air ( low pressure ) .
I do agree with one of the previous posts to use thin paint and multiple passes, but sometimes I just can't wait ( my impatients causes me lots of problems )
anyway,, point of it all is I love my aztec ! :-)