HVLP spray gun recommendations

[Michael Drew]

I do not spray too many projects. I'm a weekend warrior only....

I have a CH system that has seen little use. It's been discontinued as far as I can tell. It's the HV2500, 58 CFM and either 5 or 6 psi. Here's a link to the Amazon page for a visual reference. https://www.amazon.com/Campbell-Hausfeld-HV2500-Finish-Sprayer/dp/B0002FT8RO

The sprayer works well enough for my needs, but only if I keep the gun in the vertical position. I'd like to get a different sprayer that will work with this turbine compressor but will work in any position. I have been surfing around the net trying to find a suitable gravity feed gun with the "HVLP" designation, but when I look at the spec's, these guns tend to have a 20psi or greater minimum air pressure requirement.

I tend to use water based poly more than oil-based products. I just don't like the mess that comes with oil based stuff. Polycrilic is my go-to stuff product, now that I think about it....

One particular sprayer that my surfing led me to was the Graco HVLP finish pro edge II plus. Would this be a good choice? Are there others I should be looking at?

[John TenEyck]

You need a gun made for a turbine system. If you get one with the 3M PPS H/O system you will be able to spray at any angle, including upside down. Here's a link to help educate you. I'm not suggesting you buy one of these guns or from Homestead; it's just so you can learn about some options that might work for you.

John

http://homesteadfinishingproducts.com/products-we-offer/hvlp-spray-equipment/3m-turbine-guns/

[Michael Drew]

Thank you John. I do not recall seeing the "turbine" designation while surfing. What does PPS and H/O mean. I'm not very painter acronym proficient.

[John TenEyck]

Your spray system is a turbine unit so you need a gun designed for one. Go to 3M's website to learn about their PPS system and the H/O cup.

Your spray system is pretty low end. I would not invest more money in it. I would use it for what it's capable of and buy a more advanced system when your needs/means justify it. IMHO, a compressor and conversion gun offers more benefits per $ spent.

John

[Patrick Chase]

You need a gun made for a turbine system. If you get one with the 3M PPS H/O system you will be able to spray at any angle, including upside down. Here's a link to help educate you. I'm not suggesting you buy one of these guns or from Homestead; it's just so you can learn about some options that might work for you.

John

http://homesteadfinishingproducts.com/products-we-offer/hvlp-spray-equipment/3m-turbine-guns/

Standard non-H/O PPS can spray upside-down as well. That's why there's a hole in the bottom of the non-H/O cups. You hold the gun cup-down (upside-down for gravity, rightside-up for siphon), push through the hole and up on the liner until the finish is "primed" all the way to the nozzle, and you're good to go.

H/O is certainly preferable if your rig can supply cup pressure, for a few reasons.


You get more consistent finish output regardless of gun orientation. Gravity contributes +/- 0.5 psi or so depending on orientation, which can be significant with an unpressurized cup. Put another way, the difference between -0.5 and 0.5 psi is more noticeable than the difference between 4.5 and 5.5 psi in my experience.
Cup pressurization makes it a lot easier to spray thick finishes like latexes (though even so an HVLP gun is never ideal)
It's self-priming. Instead of the "poke the liner" drill I outlined above you just hold the gun cup-down, pull the trigger, and let the pressurization drive all of the air out.


My touch-up gun is unpressurized, and works perfectly well upside-down with non-H/O PPS. I also sometimes run my PPS-only 3M "dispose-a-gun" (the HGP model (https://www.3m.com/3M/en_US/company-us/all-3m-products/~/3M-Accuspray-HGP-Spray-Gun-Kit/?N=5002385+3293193663&rt=rud) which has pressurization) with pressure feed blocked, because its smallest 1.2 mm N/N is too fast for some stains etc with cup pressure.

[Patrick Chase]

Thank you John. I do not recall seeing the "turbine" designation while surfing. What does PPS and H/O mean. I'm not very painter acronym proficient.

EDITED to reflect the fact that the OP's system has a pressurized siphon cup.

PPS is 3M's Paint Preparation System. It's a system of cups and disposable liners. Among other benefits it allows upside-down spraying in all variants (not just H/O). This video provides a decent overview https://www.youtube.com/watch?v=CIC2fuUAP4E. Note that the configuration they show is non-H/O, and they specifically demonstrate upside-down spraying.

The cheapest way to get what you want will be to buy the appropriate PPS adapter for your current gun (probably a #18 - most siphon guns with standard standpipe threading use it) and a starter set of consisting of a PPS cup, liners, and lids/filters. Your system does have pressure feed, so you'll want the more expensive H/O cup
. The price of the upgrade will be $150-200 total, though everything but the adapter (and probably even that if it's a #18) will carry over to your next system.


IMO this is particularly true given that your system is fairly "weak" at 5-6 psi. Cup pressurization will allow you to squeeze thick finishes through relatively small N/N, and that in turn reduces the amount of pressurce/cfm needed to atomize those finishes.

[Michael Drew]

Thanks for the information. That is very helpful. That PPS set up is pretty slick. I want it now...... I also would really like a smaller gun for spraying cabinets and shelving units I tend to build on a frequent basis. The gun I have now is simply too big to reach inside most of my projects.

The HVLP system I have was a gift, and I didn't bother to look into quality or price. I got it because I was complaining about using a brush on my projects, so my girlfriend bought it for me. She took the initiative to look at my compressor and ask questions. My compressor is just a small 30-gallon garage unit. 7.2 CFM at 40 psi and 5.7 at 90 psi. I do not believe it is adequate for a standard pressure or conversion gun. If my compressor is capable, I'll get a conversion gun. Actually, I'm beginning to think I should just get a bigger compressor anyway......It's pissed me off more than once not keeping up with my pneumatic tools.

For the time being, I'll look into what it will take to convert my existing gun to the PPS set up.

With consideration to moving to a pressure or conversion type spray set up, what would you guys recommend as minimum compressor requirements? I am space limited though, so size will play into this.

[John TenEyck]

If your compressor can push 7 cfm at 40 psi it's more than large enough for an LVLP conversion gun, which will do everything an HVLP gun will, just a little slower. If you do move up to a larger compressor a vertical tank model will preserve space.

John

[Patrick Chase]

For the time being, I'll look into what it will take to convert my existing gun to the PPS set up.

If you want to spray inverted then you'll probably end up with PPS (or one of its clones like DeKups or SATA RPS) no matter what. Your only other realistic option is a remote pressure pot, which avoids the cost of liners and lids but is a lot of hassle for small jobs.

That being the case, the only "wasted cost" that you might possibly incur by upgrading the gun you have is the cost of the PPS adapter. Everything else can be transferred to any new gun you buy down the line. As noted above there's a decent likelihood that your gun uses the #18, which costs $30 and is very likely to be compatible with any future siphon-style guns.

One other thing to consider is the possibility of getting a small conversion (compressor-driven) detail gun to supplement your existing system instead of replacing it outright. Given that you've expressed a lot of concern about working in tight spaces you're probably going to end up with one of those anyway before long, and they'll work fine with your current compressor. If you spray waterbornes then make sure to get one with stainless fluid passages.

On a final note, 30 gallons is a decent amount of tank capacity and should allow you to use a slightly "hungrier" gun than your compressor's scfm rating would suggest. Let's take the fairly typical setup that John uses (a QualSpray 6008 HVLP conversion gun) as an example. Assuming that you start out at, say, 150 psi then that tankage alone would be enough to run the gun at max pressure for ~2 minutes before inlet pressure becomes an issue. Your compressor runs at 70% of what the gun requires, so you should be able to go for ~7 minutes straight with the compressor turned on. For furniture work we typically don't shoot continuously for that long, and if we do then it's complex work where we'll have the pressure turned down to avoid blasting that much air and finish around, which will make the tank last (much) longer. The bottom line is that if you have that much reserve and don't plan on painting huge surfaces in one go, then I wouldn't worry too much about getting a gun that's faster than your compressor.

Also keep in mind that big air-hogging guns don't need to run for as long continuously because they spray more finish.

EDIT: FWIW, my compressor is a cheapo one that maxes out at 5 scfm, that charges a 15 gal tank at 200 psi. I'm limited to 120V single-phase, so when I started spraying the cheapest option I could find was to plumb a 30 gal 200-psi-rated receiver tank into the unregulated (200 psi) side of the compressor. I can go for a decent amount of time starting from 45 gallons at 200 psi, even with my most air-hungry gun (an RP gun that uses ~14 scfm at 36 psi)

Also, fixed a scaling error in converting my own rundown results.

[Michael Drew]

Thank you very much. I will buy one an HLVP conversion gun with PPS and see how that goes. My compressor is a vertical unit. 120V, single piston. Unless I can find a slightly larger one that does not take up any more floor space, I'm stuck with this one for the time being, until I build a shop.

Are the 3M guns a decent choice, or are there others that I should also be looking at?

[Patrick Chase]

Thank you very much. I will buy one an HLVP conversion gun with PPS and see how that goes. My compressor is a vertical unit. 120V, single piston. Unless I can find a slightly larger one that does not take up any more floor space, I'm stuck with this one for the time being, until I build a shop.

Are the 3M guns a decent choice, or are there others that I should also be looking at?

The 3M Accuspray "dispose-a-guns" are surprisingly good. They spray a nice uniform pattern, and disposable heads can be really handy sometimes. If you leave a curing finish in your gun by accident then you're only out a $6 head rather than (potentially) a $300 gun. For outright performance and quality of results I prefer my Fuji guns, but it's surprising how well 3M did with the simple plenum, diffuser, and nozzle geometries that they could achieve in injection-molded plastic. The only catch worth noting is that they only accept PPS, so you can't swap in a fixed cup for on-the-gun stain mixing for example.

The big decision that I see you needing to make is whether to just replace your current gun, or add a smaller detail gun for tight spaces. As I alluded earlier most people who work on furniture end up with a secondary detail gun

I think that you should take a look at Jeff Jewitt's QualSpray line. (http://homesteadfinishingproducts.com/products-we-offer/hvlp-spray-equipment/qualspray-hvlp-guns/) They're Taiwanese guns made in the same factories as everybody else's Taiwanese guns (DeVilbiss StartingLine, etc), but he specifies some useful upgrades such as stainless fluid passages and ships them in kits oriented to woodworking. The QS125WB might be a good choice for a detail gun, or the 5008/6008 for a full-sized replacement for your current setup.

[John TenEyck]

A pretty thorough run down by Patrick. But I'd like to back up and talk about what it is you are spraying. I have the Qualspray AM-6008 Smartpak that Patrick mentioned. It's a bottom cup gun; I have the 30 oz H/O PPS cup on it. It's pretty big overall, but I can shoot the inside of most anything with it by turning the gun sideways or upside down. A detail gun could get me into tighter places but I don't need that capability enough to justify buying one. Of course I have no clue what you want to spray so what works for me may not for you.

3M has a whole line of Accuspray guns, some "disposable" some not. Those sold by Homestead are not, IIRC. The non disposable ones are generally very well regarded.

I have a 60 gal vertical compressor. Its footprint is about a 2' diameter, not much more than what your compressor probably needs. If you decide to upgrade look for a used one. A hobbiest is unlikely to wear one out.

John

[Michael Drew]

If I can spray with the gun sideways or upside down, I can probably spray everything I build. That is a good point for me to keep in mind.

I had assumed earlier that the guns at the Homestead website you linked to earlier, John, were 3M guns. I should have looked closer before asking dumb questions. I'll spend some more time at Jewitt's website. I have one of his books but was not aware that he had this paint supply line.

[Patrick Chase]

3M has a whole line of Accuspray guns, some "disposable" some not. Those sold by Homestead are not, IIRC. The non disposable ones are generally very well regarded.

The non-disposable Accusprays are as good as any gun out there IMO, and priced to match. The disposable ones are remarkably good for what they are, but not in the top tier, agian IMO. Homestead sells (http://stores.ebay.com/Homestead-Finishing-Products/Spray-Guns-/_i.html?_fsub=13279906012&_sid=1148844982&_trksid=p4634.c0.m322) both (http://stores.ebay.com/Homestead-Finishing-Products/3M-Spray-Equipment-/_i.html?_fsub=13298756012&_sid=1148844982&_trksid=p4634.c0.m322) on Ebay.

[Michael Drew]

Well after spending some more time at the Homestead website, I have a better handle on my choices. I also figured out that both 3M and the Homestead Qualspray brands are sold there....duh.

I am somewhat confused over the LVLP and Reduced Pressure guns now. By reading the descriptions of both, there does not appear to be a clear winner between the two. Both look like they would work quite well for my needs and my current compressor. If there was one thing that I interpret to be a pro for the RP gun, is it might possibly be a better choice for using water-based poly?

I'm kinda leaning towards buying the AM-8008/5008 SmartPak..... That way I'd have both standard and touch-up sized guns with plenty of nozzle size choices. I'd then just need to get the PPS components.

[Patrick Chase]

I am somewhat confused over the LVLP and Reduced Pressure guns now. By reading the descriptions of both, there does not appear to be a clear winner between the two. Both look like they would work quite well for my needs and my current compressor. If there was one thing that I interpret to be a pro for the RP gun, is it might possibly be a better choice for using water-based poly?

LP and RP are designations based on tip pressure and transfer efficiency, respectively. "LP" means that the tip pressure is 10 psi or less. "RP" means that the tip pressure is greater than 10 psi, but the transfer efficiency (percentage of finish that ends up on the work as opposed to in the filter) is greater than 65% for some standardized test conditions. In theory an RP gun should require somewhat less cfm to deliver a given amount of finish than does an LP gun.

See this page (http://www.aqmd.gov/home/permits/spray-equipment-transfer-efficiency) for information about the regulatory framework that created both classes of gun. HVLP guns are always permitted for commercial use even in high-air-pollution areas. RP guns are only permitted if the vendor has demonstrated 65% transfer efficiency. It's probably worth noting that top-quality LP rigs can have transfer efficiencies in excess of 80% depending on finish and conditions, so there is an efficiency (blowback, overspray, etc) downside to RP. The "RP" branding just tells you that it isn't any worse than 65% under standardized conditions.

LV vs HV is less clear cut as it doesn't have a legal/regulatory definition as LP/RP do, though the breakpoint is generally around 6-8 cfm depending on vendor.

There is huge variation within both LP and RP guns. My RP gun (a Fuji MPX-30) takes ~13 cfm at its max inlet pressure, so I suppose you would call it "HVRP". It's *really* fast at max pressure and can atomize most anything I care to spray without thinning. The RP gun that Jeff sells takes 6 cfm, so that would be LVRP.

IMO for woodworking finishes including waterborne clears a good HVLP gun is more than sufficient. I seldom work at the full rated inlet pressure even with those. It's probably worth noting that for an LP gun the rated inlet pressure is the highest pressure that produces <10 psi at the tip, after conversion. For an RP gun the rated inlet pressure is the highest pressure that the maker certifies will produce >65% transfer efficiency under standardized conditions. There's no magic here :-).

[John TenEyck]

I think you are going to want to add at least one larger N/N set for the 5008 gun if you want to spray many WB products, especially any pigmented ones, without thinning. When I was using gravity guns I mostly used a 1.8 mm N/N for the GF WB clearcoats I sprayed, and had to thin every pigmented product. That was a primary driver for why I went to a pressure assisted setup.

Of course, you could modify the 5008 gun to run a pressurized PPS cup as an alternative to using a larger N/N.

John

[Patrick Chase]

Of course, you could modify the 5008 gun to run a pressurized PPS cup as an alternative to using a larger N/N.

I asked Jeff about that about exactly that a while back (just after the last time this topic came up) and he suggested using the 6008's cup regulator (https://www.ebay.com/itm/QualSpray-AM-6008-PR-Regulator-Assembly-Pressure-Cups-/252618806051?hash=item3ad1411323) with a PPS-equipped 5008.

Note that the "HGP" (https://www.3m.com/3M/en_US/company-us/all-3m-products/~/3M-Accuspray-HGP-Spray-Gun-Kit/?N=5002385+3293193663&rt=rud) version of the 3M dispose-a-gun also has cup pressurization built into the gun body. It's just about the only conversion gun I know of that can do that (the 6008 relies on the aforementioned external regulator, as do the CATech guns with cup pressurization).