Small-Compressor/HVLP Setup

Finishers debate whether a small compressor paired with an HVLP spraygun can get the job done. February 19, 2006

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?

Forum Responses
(Finishing Forum)
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

From the original questioner:
I've been reading a lot on this and other websites and there are also (super) low HVLP guns out there (Astro 40005/40007).
The 40005 specs are:

Operation Pressure: 29psi
Net Weight: 1.47 kgs (3.23 lbs)
Dimensions: 233 x 165 x 140mm (spray gun)
Avg. Air Consumption: 6 cfm (4.8CFM for wood)
Air Inlet Thread NPS: 1/4"
Recommended Compressor: 2hp
Max. Pattern at 8" Distance: 200mm
Air Hose I.D. Size: 3/8"
Nozzle Size: 1.5 mm (#40007)

So that's where I based my conclusions on (4.8 cfm for wood).

From contributor B:
The compressor and gun(s) you're looking at are a good match, especially considering the light use you intend.

From the original questioner:
Does anyone have experience with the Astro 40005/40007 or any other good super low HVLP guns? As for the nozzles on the 5 and 7 are 1.5 and 1.7, do I buy both, or will I be fine using the 1.5?

From contributor A:
Gathering a bunch of opinions as well as facts and figures, as you have done, is the best thing you can do. If you go by opinions then I am in a minority regarding the Astro gun because I am not shy about writing why I dislike the gun. In my opinion, it lacks good ergonomics, and lacks machined parts that are of consistent quality, so that buying a gun is hit and miss. I have yet to lay down a class-A finish with the two Astro guns that I use. Going by your reporting of the facts and figures the smallest compressor recommended is a 2 hp compressor and you want to get a 1.75 hp compressor. Furthermore, horsepower means nothing at all since it is a useless measurement. What counts is how much cfm you can deliver to the gun.

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.

From the original questioner:
I found a 8.8cfm/40psi 3HP oil compressor for less - no tools - but I don't really need those. Together with the low HVLP Astro's ($140) I think I'm good for now, unless again somebody knows a better gun for this compressor.

From contributor C:
Buy an Asturo Eco/S. It'll run off of a 2.5 HP compressor. It only takes about 5 cfm at 20 psi. Better yet, get a Kremlin.

From contributor D:
Low cfm guns don't atomize correctly. Bigger gun tips use more air, so smaller is better when running on a compressor. Big tips and low cfm is a disaster. 3hp is minimum for keeping up with air use. Dewalt makes a great compressor for around $300 that will fit the bill. I don't remember its name but it sits on its side and is portable with twin tanks. You can run a high cfm gun at lower cfm but it is not as good. Look for a gun around 9-10 cfm, that should be about right. Asturo is the only company that I know of that makes a good low cfm gun.

From contributor E:
I am also looking for a gun I can run off a small compressor. I'll be shooting waterborne 99% of the time for touch-ups in the field. I'm looking for a very small gravity gun as it will have to fit in my checked luggage. So far I have seen a Porter-Cable touchup gun that comes with a .8 tip and wants 5 CFM and a Jet HVLP touchup gun that seems to be a clone of the PC, except for the HVLP with a 1.0 tip and wants 3 CFM. Another one I've found but haven't seen yet is the Iwata, which says it only wants 1.8 CFM with various tips. Does anybody have experience with any of these or have a comment?

From contributor F:
You might want to check out the Accuspray 19c gun.

From contributor G:
The other option you have is a Binks Mach one. You can get a 90p air cap which will run well off a two hp compressor. You can also use a 94 fluid tip - it is about a .50.

From contributor C:
I have a Kremlin and some SATA guns but that Asturo Eco/S is a very good gun - not quite a Kremlin but it atomizes just fine. I highly recommend it. Actually, I believe the gravity cup model uses about 6 cfm with a 21 psi inlet pressure. A lot of small compressors can keep up with that.

From contributor H:
I do a lot of touch-ups in the field for a local cabinet company. For most small touch-ups I use a 3hp compressor with 11 gal tank. I also have an Iwata RG-3 gravity gun. The trigger action and control is outstanding. I can spray for quite awhile without the compressor starting. For coating panels I have a turbine unit and Accuspray #10 guns. I have an arsenal of spray equipment that I use accordingly, depending on what army I'm up against.