PC HVLP - whats my problem??

[GaryA]

I think I screwed up here. I bought a Porter-Cable PSH1 HVLP gravity fed gun (first time HVLP or any paint gun user), and have been trying to spray finish my MDF cabinets/built-ins. Oil based primer & then latex semi-gloss. The primer got a lot of spatter, and I ended up sanding it smooth and foam rolling (yes, small bumpy finish). I then bought the bigger nozzle (2.0) for the gun and tried the latex. Got pretty close to the same results, and realized that the air pressure dropped significantly after a few blasts and the compressor was constantly running. In reading some other posts, etc, I think the problem is the size of my compressor. I have the Porter-Cable pancake compressor. I had thought that since it was "low pressure" that you didnt have to have a monster compressor to run it. Does this sound like the problem?

[Thom2]

Stated specs on the gun:

Air Consumption @ 40 PSI: 8.5 SCFM

Stated specs from a CPFAC2600P 15 Amp 2-Horsepower 6-Gallon Oil-Free Pancake Compressor:

Provides 3.7 cfm at 40 psi

A pancake compressor definately won't handle that gun, you need more than twice the compressor to even start to run that gun for any length of time.

[mpc]

Pressure is only part of the air compressor story... air flow rate (measured in CFM - Cubic Feet per Minute) is really the big issue in compressors. HVLP is "High Volume" so you need lots of CFM from the compressor. Few pancake style ones have much volume at all; they tend to be designed for nail gun applications. Even bigger tank style compressors can have issues with HVLP guns.

Think of it as trying to fill a swimming pool with a hose the size of a soda straw... lots of pressure won't help; the volume of water is limited by the dinky straw diameter. Now switch to a fire hose. Same water pressure but a LOT more flow - the pool will fill up many times faster. That's the type of CFMs the HVLP sprayer typically needs. There are HVLP kits (Rockler, Woodcraft, and Harbor Freight sell basically an identical unit) that combine a small/noisy fan to make low-pressure high-CFM airflow with the HVLP spray gun. Either that, or upgrade to a big compressor.

Most of the Sears compressors, Husky, etc. that you see have gone to the "oilless" style - and with great big "125 PSI" or "150 PSI" labels. Those tend to be noisier and low CFM. Compressors with fancy plastic covers over the mechanism tend to fall into this category. Higher flowing compressors have exposed & air-cooled ribbed cylinder assemblies - they look like a Harley motorcycle engine. 6.0 CFM is about the max you can expect from a compressor running on a 120 volt outlet; beyond that you need 220volts and more amperage (i.e. a higher horsepower electric motor driving the compressor) or a gas-engine powered compressor.

mpc

edit: while I was typing on and on Thom2 snuck in ahead of me and said the same thing in only two succint sentences.

[LCHIEN]

Clearly not enough air flow volume. You need the monster air compressor.

[GaryA]

Sh*t! What to do.... Thanks guys...great info, and lesson learned. Not typically like me to jump in without knowing the requirements. Anybody wanna buy a barely used PSH1 ?

I dont think I have the room for a bigger compressor in my 1 car garage shop. I do have 220, so that wouldnt be a problem. Floorspace is the issue. If you had to point to a compressor that would handle this gun and was relatively quiet (possible?) any suggestions?

mpc, you mentioned a self-contained HVLP kit system. Guessing you are talking about this: http://www.rockler.com/product.cfm?O...Select=Details What kind of results can these give? Same/similar as I'd get from the PC? Are they hard to clean? Seems pretty reasonable at $99 - why is this one so cheap compared to some of the others? Would I be better to spend closer to $300 for something like this Earlex: http://www.woodcraft.com/family.aspx?familyid=20047 .

Thanks again for the help. I should have asked before I bought...

[mschrank]

mpc, you mentioned a self-contained HVLP kit system. Guessing you are talking about this: http://www.rockler.com/product.cfm?O...Select=Details What kind of results can these give? Same/similar as I'd get from the PC? Are they hard to clean? Seems pretty reasonable at $99 - why is this one so cheap compared to some of the others? Would I be better to spend closer to $300 for something like this Earlex: http://www.woodcraft.com/family.aspx?familyid=20047 .

Thanks again for the help. I should have asked before I bought...

There's been quite a bit of discussion recently about the HF/Rockler/Woodcraft HVLP turbine unit. I bought one and have been very impressed, but my experience is very limited. I don't recall seeing any real negative comments, especially when you consider the price. btw, the Harbor Freight version is on sale now. I think you might consider the $300+ hvlp systems if you do a lot of spraying, but for the average woodworker/hobbyist, this little unit works great. Easy cleanup too!