questions about paint guns & related equipment

[jesusgatos]

OK. I need some help. Just bought one of these HVLP paint guns from Harbor Freight (part number 93305 if the link doesn't work). I've never used a paint gun before, and I'm not finding the instructions very helpful (typical HF). The instructions are actually so bad that they tell you to hook-up the paint/air lines backwards in one diagram. Fortunately I figured that out before I actually tried to paint anything...

I bought a glad-hand hook-up to the service-air line, and I've connected a cheap desiccant air filter from HF to that. Then I put a mini-regulator inline behind that, and connected my air hose to that. The instructions say to regulate the incoming air to 30-43psi. No problem.

Then they say to set the regulator on the pressure-cup to 10-30psi. But I've tried adjusting the regulator from all the way open to all the way closed, and it doesn't seem to have any effect on the air pressure at all.

I've managed to regulate the pressure by bleeding-off the majority of the excess air pressure through the safety valve, but I'd still like to figure out what's wrong with the regulator on the pressure-cup.

I've painted some cardboard boxes and small parts, and I'm thinking this might actually work alright (assuming I can figure out how the regulator is supposed to work). I know this is a little bit ghetto, but am I crazy to think that I might be able to use the air compressor on the deuce to paint the deuce?

Next question: I'm going to relocate my air tanks and run new air lines soon. When I do that, I was thinking that maybe it would be a good idea to plumb a nice air filter/dryer into the system. Should I look at components that would be used in a shop, or would I be better of using one of those air dryers like the big rigs put in trucks? If I use shop components, I'm guessing that I'd need to run them on an accessory line that I can turn on/off (in order to keep from losing air pressure to the brakes if any of those components failed). I think I've seen some pictures of a few trucks that people have installed these type of air filters/dryers on, but I can't find any of them now.

 

[Nonotagain]

With the lid of the pressure pot off of the cup, see if you have any air flowing from the small hole in the cup lid. If the regulator won't adjust the air pressure by unscrewing the regulator knob, take it back to HF.

You should not need more than 10-15 psi to force paint up the tube into the gun.

I can't tell if the knob on the side of the gun adjusts paint flow or the fan adjustment.

As for a filter regulator, Make sure that the lair line that you are using to feed the assembly is moisture free by draining the air tanks on the truck first. If the filters get a slug of oil and water they will be trash.

You can verify air cleanlyness by using a blow gun and blowing your compressed air onto a mirror for a minute. If you see a halo on the mirror you have oil or moisture present and need to flush/bleed the tank again.

 

[jesusgatos]

OK. Got the pressure-cup regulator problem figured out. The regulator isn't labeled and the instructions said to hook the hoses up backwards in/out. Switched the hoses around and all is well.

Thanks for the tips about draining the tanks and checking for oil/water. I'd still like to get some recommendations about which components I ought to plumb into the air system. Specifically looking for the overkill option here...

 

[WPNS421]

I have used an HVLP gun for the last 15 yrs and they are great. I use an Accuspray(they invented HVLP) now sold as 3M. In my guns you bring up to 100PSI and the regulators will bring it down to the required 6 - 15 PSI. What you have to know is that HVLP means High Volume Low Pressure, make sure that your air line diameter is at least 1/2 to 3/4 in . The deuce will definitely not provide sufficient air to your gun and pressure pot. An option to look at is using a turbine to feed the air to your gun. I have a turbine, it plugs intoo a 110V outlet and then to the gun. The advantage you have water free, oil free warm air and you can use the gun anywhere as long as you have power.
The truck on my avatar was painted by my HVLP turbine gun, It also has painted all my other trucks. The gun I use can work on my turbine and on my shop compressor. It is worth the money I paid for it. Look into the turbine, figure the cost of water separators, oil filters etc versus turbine.

 

[jesusgatos]

Thanks for the info and opinions guys. I did paint some stuff today, and the air tanks ran down to 50-60psi, but seemed to hold there pretty well. I'm thinking that if I add a larger air tank that might help with recovery times. I'd like to know more about that turbine. Can you tell me what I should search for or maybe hook me up with a linky?

 

[WPNS421]

Just Goggle Accuspray HVLP Turbines and it will bring you to a link. I use the 230 nseries turbine, it takes my regular gun and my gravity feed gun. The real nice thing about a turbine you don't have to play with any regulator, you just use the controls on the gun. I spent the money and got a real good system, In Canada the systems cost 25% more than in the US and in the past few years the price of this type of eqpt has dropped. My system can guns can use the turbine, the shop compressor, a small pressure pot and a large pressurepot. The best feature on the Accuspray gun is being able to open the gun in two for extreme cleaning(paint hardened in the gun) changing leaking packings and repairing or changing a busted handle or body.
The gun can also handle any paint, no matter what the viscosity. In this gun you can change the needle and the nozzle in under 2 minutes, so you can use a .027 point base coat clear coat paint for cars and then jump to a .043 or .051 needle for CARC paint, also the thicker you apply the paint the less coats you have to put on.
When I was in the military I was the Life Cycle Material Manager for spray pai nt equipment for the entire Cdn Forces and I introduce HVLP to the Canadian military. In the field the guys really love the turbine, they can spray paint using a generator for power. As you can see I really like this system.

 

[WPNS421]

P.S. If you think the gun is expensive, I have been using mine for over 17 years.. Cost/no yrs

 

[jesusgatos]

Man, that looks like a FANTASTIC system. I've never seen anything like that before. Thanks for the info!

 

[Nonotagain]

OK. Got the pressure-cup regulator problem figured out. The regulator isn't labeled and the instructions said to hook the hoses up backwards in/out. Switched the hoses around and all is well.

Thanks for the tips about draining the tanks and checking for oil/water. I'd still like to get some recommendations about which components I ought to plumb into the air system. Specifically looking for the overkill option here...

You can't afford the overkill approach, trust me on this.

I use Wilkerson filters for my spray paint needs at home.

I have two filters in series. Both filters are 1/2 pipe thread. The first is a M16 coalescing filter and the second is an after filter AF2.

The first filter is a 5 micron filter and removes oil and moisture and has an automatic drain. The after filter is a .5 micron filter and catches what the first filter misses.

Mount your filters as low as possible then raise the airline so that it acts as a catch trap.

The HF HVLP spray guns probably don't meet the cap pressure requirements to truly be labeled as HVLP. I have been unable to locate a cap with pressure gage to test for atomization pressure. The only issues that I have seen with the HF spray guns are that the supplied in-line regulators don't seal to the gun fitting very well.

The Accuspray spray gun has been around since 1988 as I still have one of the first guns produced. The spray finish produced by gun was very crude. The limited number of tip/needle combinations coupled with air caps as well as the large diameter hoses meant failure in most industrial environments. Another issue with the guns is the composite body which always seemed to attract paint overspray.

Accuspray guns were also sold under the name of AirVerter before being purchased by 3M.

For large users in the US, Binks and DeVilbiss rule the market. The problem with both of these companies is that they are owned by ITW (Illinois Tool Works) and they don’t offer as many specialty guns and cups as previously produced when they were two separate companies.

DeVilbiss offers tip/needle combinations from .017” all the way up to a whopping 3/8” fluid tip. Binks guns have better ergonomics than the DeVilbiss guns, though they as part of ITW are now sharing a product line being offered to body shops.

Getting back to the HF spray guns. The company that I work for has been issuing HF guns to most of the production painters for the last two years. For the price of the gun verses having to replace tips and needles every few weeks, it’s worked out far cheaper to just issue the HF gun and throw it away when the parts wear out.

 

[cbvet]

I used that same HF gun to paint a Deuce. Came out great!

 

[Blood_of_Tyrants]

Okay, typically the spray pattern is 90 degrees from the position of the two tangs on the spray head. Your paint should be thinned to about the thickness of cheap syrup or just a bit thinner. Turn up pressure to the pot until you get paint out. If the paint splatters, lower the pot pressure and adjust the paint flow knob for less paint or raise the spray pressure (or even all three).

I have one of these pots and sometimes the little bras pin under the pot lid gets stuck after sitting for a few days. Use a pick to move it if it has stuck. It will probably work fine after that.

Proper spray pattern should be a long oval and the droplets should be very fine.

The top knob on the back of the gun adjusts your spray pattern. All the way in and it shoots a blast in a small round area. Great for reaching way back into that wheel well, but it puts out a lot of paint, so be careful.

The bottom knob in the back of the gun adjusts the paint flow. Pull it halfway back and get air only. Pull it further back to start the paint flow. Counterclockwise increases paint flow, and clockwise does the opposite.

Get some paint filters and us them to filter the paint as you pour it into the pot.

Always start moving your gun BEFORE you pull the trigger.

Keep the paint gun parallel to the surface and avoid sweeping arcs as this makes the paint thicker in the middle and thinner at the ends

Release the trigger BEFORE the end of the stroke.

Your stroke should be only as long as you can comfortably reach.

Overlap the strokes by about 1/3.

Two or three thin coats are better than one thick and runny coat.

Now for the bad news. That spray gun is a piece of crap. Go to epay or craigslist and get a good used Binks model 7 or a Binks Mach 1. Think about it, if it really were a "professional" paint sprayer, would it cost $50?