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HVLP question

Discussion in 'Open Bar!' started by Neural, Apr 3, 2018.


  1. Neural

    Neural Gravity Guru

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    Wasn't sure if this was right for the Airbrush section, because it's not *really* an airbrush..

    I bought a HVLP detail gun (Harbor Freight) and have a troubleshooting question.

    There are two parts to this that may be causing the problem I'm having.

    I was going to run some cleaner through the gun from the cup. The manual stated that it needs to be disassembled and the needle/head/etc. soaked in cleaner (warm water and soap, while some videos suggest thinner) in order to remove the manufacturing lubricant (which appears to be Kerosene or similar).

    Initially running just water through it, I ran into the following problem.

    It sprays for about 1/2 to 1.5 seconds, then stops, and instead kicks back up into the cup.

    I *suspect* it's an air pressure issue. I have my main compressor set to around 40 to 45, but it's difficult to really nail down. The HVLP came with an in-line regulator, but ...well.. let's just say I have issues with regulators in general.

    If someone could point me to an idiots guide to using regulators, I'd love to see it, because with the air compressor set at 45, it seems to me that fine tuning it at the in-line regulator would be easier, but if I try to go below 40psi (not for the HVLP, but just to test), the knob that adjusts the pressure starts to leak air.

    Are you supposed to adjust the pressure with the line open? Is a *lack* of pressure possibly causing the problem with the spray gun? Is the regulator that came with the spray gun just a piece of crap? If so, can anyone recommend an in-line regulator that is less than $50?

    Thanks. :)
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  2. Jurien72

    Jurien72 Have Airbrush - Will Travel!

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    I have no clue about your problem, but I think it is safe to say that any device with air going in one end and paint coming out the other qualifies for discussion on this forum :thumbsup:
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  3. JackEb

    JackEb The Dragon Hunter Staff Member Admin

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    i'm no expert with spray guns but a few things you've asked are the same for guns & brushes. The air pressure is always set with the line open. Its what is refered to as 'operating' or 'working' pressure.
    All airbrushes/ guns should be cleaned prior to use
    Is your compressor capable of delivering the volume of air (litres/gallons per minute) that the gun needs ?
    Bubbles in the cup, Fluid tip not tight – tighten the tip
    If you link the spray gun you have and what compressor you have we may be able to figure it out between us until the experts arrive and shoot us all down in flames for giving the wrong answers lol
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  4. JackEb

    JackEb The Dragon Hunter Staff Member Admin

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    what ever troubleshooting you would do for your airbrush you could translate to the spray gun
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  5. Neural

    Neural Gravity Guru

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    LOL. ok. I'll poke at the working pressure and make sure the tip is tight. As for the CFM, I have a CAT 15020C which will do 6.4CFM at 40psi. The gun has a requirement of 5.6cfm (40psi), so that shouldn't be an issue.
    I'll tinker a bit and get back with more info.
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  6. Jurien72

    Jurien72 Have Airbrush - Will Travel!

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    I'd love to know what my compressor is capable of for CFM
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  7. JackEb

    JackEb The Dragon Hunter Staff Member Admin

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    most of the time it will be on the manufactures website
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  8. JackEb

    JackEb The Dragon Hunter Staff Member Admin

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    strip it down and clean it and run cleaner through it as well, then test drive it with water, they may be a bit of crud blocking the nozzle if you havent broken it down yet
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  9. Neural

    Neural Gravity Guru

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    Ok, so the tip is definitely secure, and the pressure is in the right range, but there's definitely something odd going on with the flow. The air pressure is constant, but the flow of liquid (just using water right now) is really odd. Goes for a second or two, then stops unless I shake the gun or release the trigger and then start again.
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  10. ilzeairbrushing

    ilzeairbrushing Needle-chuck Ninja Very Likeable!

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    Yup check the release trigger also ensure no gue from the kerosene is stuck in the nozzle.... dissemble soak and clean is the best I can think of, as something is obstructing the flow sound to me like a clot of paint is getting stuck
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  11. Micha der Wolf

    Micha der Wolf Detail Decepticon! Very Likeable!

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    Have you pictures from the dismounted head ?
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  12. huskystafford

    huskystafford Mac-Valve Maestro!

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    what kinda gun you bought? Cheap chinese? You got link maybe? I am just interested in this topic, I can learn a lot and use it down the road, when I will get my guns.
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  13. Neural

    Neural Gravity Guru

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    @ilzeairbrushing Perhaps that is the issue.
    @Micha der Wolf I'll take some pictures and cell phone video
    @huskystafford Does Harbor Freight deal in anything but cheap Chinese? lol. I've actually heard a decent amount of positive about the HF detail guns. This one was the cheapest 4oz. gun they had which came with a regulator. Part #61743 https://www.harborfreight.com/4-oz-hvlp-touch-up-air-spray-gun-61473.html

    Per the manual, you don't want to soak the entire gun in a cleaner, but in one particular review video, the person doing the demonstration put the forward part of the gun into lacquer thinner to soak (the portion where fluid flows through, so cup inlet to nozzle).
    I don't have any thinner, but I can get some. The only thing I have on hand are household cleaners, and alcohol (I think it's 80%).

    For future use, does anyone know if the Createx paints (specifically, but not limited to, the Auto-Air colors and 4030 adhesion promoter) are a bad mix with Isopropyl Alcohol? I have it handy because I use it for working with resin. I have a small amount of Restorer, and some more on the way, but I'm looking for something that isn't as expensive that can be run through the gun to clean it out.

    Sorry if this is all way off course with the water-based. Again, my experience from long ago was using Testors brand Modeling paints, which you thinned with turpentine based thinner, and thus could also clean with said thinner.
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  14. huskystafford

    huskystafford Mac-Valve Maestro!

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    Sorry I am from Europe and I don't know much about Harbor Freight. Is it possible that issues with that gun are cause of bad manufacturing?
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  15. Neural

    Neural Gravity Guru

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    Very possible. :) My over all experience with Harbor Freight is that if you need a tool fast and at low cost, it is a good place to go, but you also risk getting a tool that will only do the job once (if at all).
    I started grinding aluminum with a $17 4.5" angle grinder, and it has taken a ton of abuse, but when I bought a $45 Black & Decker, it was a huge step up (and even Black & Decker has a reputation for being cheap). The Harbor Freight one (made by Chicago Electric) does the job, but the more expensive one is slightly lighter, is better balanced, has some better options, and just feels better overall to use.

    There are some products that have a decent reputation, but the store also has a 90day return policy. If I can't get this spray gun working soon, I'll take it back and either get a refund or exchange it for one of the others.
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  16. huskystafford

    huskystafford Mac-Valve Maestro!

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    Maybe just take it back so you don't waste your time and get another the same one as replacement and test the replacement. -.-
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  17. Leakyvalve

    Leakyvalve Gravity Guru

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    Sound like the needle seal isn't working properly. I bought a couple chinese made mini guns, not HF, and they were the biggest POS I have ever seen. Nothing worked right and they leaked and sprayed like crap. The seals were some sorta mashed up junk rubber that instantly failed and it was full of actual grease, the worst possible pollutant you could ever have spraying solvents.
    I ended up just get an 1.2mm lph80 and it is a super mini powerhouse. Get some sort of name brand, even a ANI R-150 will get small jobs done for a good deal and has good reviews.
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  18. jord001

    jord001 Air-Valve Autobot!

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    Neural, the guns should run at about 30 -35 psi, 2 - 2.5 bar, so not that high really, What compressor do you have? I had a small gun with my Iwata Power jet Pro, It was broken so used it for parts but the compressor had been running it and they're not massive things and only have a 2 or 3 liter tank. So the problem could be that you don't have enough volume of air being produced by the compressor, that would explain why it works after you stop for a second or two but it should spray for more than a few seconds anyway. But as its been said you should be able to check what the cfm is for it. We can troubleshoot from there when you check.
    Cleaning, Isopropyl Alcohol should work, but any gunwash/urethane thinners will work and is usually about 15 for a gallon, may be cheaper and you should be able to get it from HF or Lowes, Micheals, Hobby Lobby maybe, I don't know being that i'm in England.

    Lee
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  19. JackEb

    JackEb The Dragon Hunter Staff Member Admin

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    Lee, Neural has already provided the CFM of the compressor and gun, its close to running on max but should give enough for it to work, it may be spasmodic when the tank has to refill but even so, should still be enough to play around with i think

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  20. jord001

    jord001 Air-Valve Autobot!

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    Sorry, missed that bit :) its been a looooong day.
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