I want to buy a setup using a gravity feed spray gun (easy to clean up and change) and a small ~20 gallon, 1.75 HP (~6.xcfm/40) compressor. I will use the compressor for other purposes too. That's why I'm not interested in a turbine. I've been looking at Astro and Titan. I'm a one man company, mainly building furniture but not finishing it. I'm looking at spending about $400.
1. Will a 1.75hp - 6cfm/40psi 20 gallon work for me, such as an Astro DX3/DX5 or will it run out of air in a minute? Could I even go with a smaller compressor?
2. Does anyone have any recommendations on whether or not I should get two guns or just one with multiple nozzles? The majority of my work is wood, but I may spray a personal item like a bike in the future, but no cars.
3. Has anyone had good experiences with any guns that are a low/acceptable price?
From contributor A:
You are choosing a compressor that will be powerful enough to run an airbrush. You are grossly underestimating the compressor you will need to run a gravity gun. You will have way too little cfm. The Astro is not an air hog, but it likes some cfm, certainly more than you will supply. Instead of sinking money into different size fluid sets and air caps or sinking money into more than one gun, invest in a larger compressor, at least four or five horsepower. Your spending priorities are way off the mark. What strikes me odd is that I am betting that when it comes to tools to shape and size your wood and tools that will fasten pieces together and clamps to hold the pieces together that you will have a budget that will suit your minimum needs at very least. But when your bare wood projects are ready for finishing, that's where you are going to sacrifice. There's nothing wrong with that lopsided philosophy except that you are willing to grade A woodworking only to dress it with grade C finishing. Get a turbine setup. And get a little compressor. At least you will be poised for decent finishing and you can use the little compressor for your other things, as you said. Or invest in a compressor that can deliver the air that your gravity gun will need. The most efficient gravity gun, an Asturo ECO, eats 7 cfm at 23 psi. You can get one for a little under $400. My $60 Porter-Cable PSH1 eats 11 cfm at 29 psi and my $90 Devilbiss Finishline is about the same as the PSH1. The Astro is no less of an air hog than those two guns and from my experiences they are a little more air hungry than the Porter-Cable or the Devilbiss. I do not know how you could come to such conclusions based on the research you said that you did. I suggest investigating more so that when you do decide which way to go, you make a truly informed choice
So that's where I based my conclusions on (4.8 cfm for wood).
You say that you will use a 1.5 mm. OK, look to spray on low viscosity coatings with that size nozzle set. Even more, holding an HVLP gun 8 inches from your spraying surface is often too far away. As you hold it closer you are no longer getting your 7''- 8'' fan pattern - you are getting a much narrower fan pattern. The 29 psi is with the trigger pulled and that's where the cfm requirement is really important. What does that mean "4.8 cfm for wood"? Not in my experience. Is that measurement some lab test? What are the results in a real world application? My experiences suggest much poorer performances than what I am reading for specs. I do not doubt the specs at all. So, in all fairness I am in the minority in my negative feelings for the Astro gun. Many people have them and I am assuming that what they write is accurate. Maybe I need to learn to use these guns or maybe the guns I have used are shooting the best they can which is not so great, especially compared to the Porter-Cable, Asturo and also the Kremlin Airmix. Astro is my least favorite tool at my disposal because I am using all the guns I have mentioned. Regarding the majority of Astro users who write what stellar results they are getting, I wonder if they are also willing to underpower or give the same bare minimum to their guns that you will be doing.
I hope you are planning on an oil lube compressor because otherwise you can look to see your investment break down. Oil-less compressors do not have the lasting ability of oil lube compressors. What coatings will you be spraying? Two guns make sense production wise. You can do color samples so much quicker: spray color with one gun, topcoat and lock it in with the other gun, fast and easy. Contrast that to different nozzle/needle sets. In order for you to change needles/nozzles, you need to empty your cup-above container, solvent flush the chamber and then do your parts change and make your adjustments, each and every time. One size may not fit all but you can adjust your viscosities so that it does.
Spend more and be happy. That way, when the finish is not great you can only look to yourself. When I shoot with a Kremlin Airmix there is no way I can blame the gun. When I shoot with the Astros you better believe I am going to lay the blame on the equipment rather than myself.