spray gun cleaning


I've just started using my HVLP conversion gun. I'm curious what folks here believe is a good practice as far as cleaning goes. So far, when I'm done, I spray solvent for whatever I'm spraying through the gun to try and get whatever finish out. That seems basic. Beyond that, I'm curious how ofter people break down the gun and give it a "thorough" cleaning.
todd
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todd wrote:

When I clean mine, I put an inch or so of the solvent into the cup, shake it vigorously for about 20 seconds and then spray it out. This always leaves something on the bottom of the cup, which I pour out. Then I clean the cup and any material off the gun and especially the rim of the cup since that has to be almost spotless for a good seal.
I put another inch or so in the gun, open the fluid valve all the way and shoot out all that I can, and leave the rest (1/8 1/4") in the bottom of the gun. I break open the locking cam to make sure there is no pressure in the gun (even from the thinner on a hot day) and then tighten it slightly before storing.
All told, just about a minute from start to finish. Maybe it's the positive pressure in the gun/cup, but these take a quarter of the time I use on my high pressure guns since there isn't any need to break them down all the time.
Robert
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todd wrote:

I only shoot waterborne finishes. I have a bucket of water at the ready, and when I'm done shooting I dump the gun into the bucket. that buys me time to deal with other cleanup, and when I can I strip the gun down and scrub it out with dish detergent using pipe cleaner type brushes. the needles and such get a short soak in a bottle of laquer thinner before the scrubdown.
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snipped-for-privacy@gmail.com says...

I only clean mine after I use it :-) That is, disassembled and thoroughly cleaned.
I didn't do that the first few times and build-up began to be noticeable and its a real pain to get off later. The solution I found was to just go ahead and plan to do a thorough cleaning after EVERY use. I do stack/plan spray projects to get more done per cleaning.
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here
done,
ofter
I completely disassemble my guns and thoroughly clean them after every use Todd. I start by dumping the cup and throwing some solvent (appropriate to the material I'm shooting, but most often lacquer thinner) into the cup. I swish and rinse the bulk of what's in there out and pour it off into a collection can. I generally give the inside of the cup a quick wipe to get most of what remains out, since a quick swish does not usually really clean the cup. With a half way clean cup, I pour in some more solvent and shoot it through the gun. I give it quite a good shot to make sure I'm getting a good amount of solvent through the passages. Then I disassemble the entire gun and clean and dry every piece with solvent. Pay particular attention to the cap. The small holes can easily clog. I store my cap, nozzle, spring, and needle in the cup with an inch or so of mineral spirits in the bottom. Make sure that you keep the seal on your cup impeccably clean. Some materials will cause you fits if they harden on. Make sure you keep the cup vent clean as well.
--

-Mike-
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Mike Marlow wrote:

SNIP of good info for brevity

Hmm... I am thinking that maybe my method is more pertinent to what I am shooting. I use my Q4 for lacquer only, and I clean immediately after shooting. I think Todd, you might want to take a look at your manual. On page 9 - 10 it tells you how to clean the gun, cup, etc. My only issue is to keep the cup seal clean so I can get good pressure when I spray again; the lacquer builds quickly and I need a scrubby to get it off the rim of the cup. I have taken the gun apart to look inside after a day of spraying (lacquer), and it is really clean inside after cleaning as directed. So far, so good.
But on the other hand, I do my >high pressure siphon< guns exactly as Mike said. I break them down to the last piece, even if I just used them for a quick touch up. When they are spotless, they work well right out of storage. But I use these guns more for coatings, primers, and sometimes alkyd enamels.
Unlike the HVLP gun, I can take apart the high pressure gun and throw it in a bucket of solvent and go to lunch, or leave it overnight. NOT so with the HVLP. It is a good thing that the Fuji is easy to clean as I do it about 4-5 times a day, switching between coatings when I am on a day of finishing.
Just remember if you do feel the urge to break the gun down, read the info in the booklet about the gun block. You cannot remove it as it is pressed in place at the factory. It is stainless steel machine pressed into cast aluminum.... don't even try.
Robert
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snipped-for-privacy@aol.com wrote:

PLEASE help. I took my Devilbiss apart and cannot figure out how to reassemble the main shaft/needle/spring so that the needle is pushed back out upon trigger release. Has anyone seen a diagram anywhere.
Thanks,
Jim
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Which model Devilbiss Jim?
You should be able to push the needle in from the rear of the gun, through the packing and then put the spring in and the adjustment knob. You'll be forcing the knob against the spring tension so it will take a small amount of force until you get the threads started. Do this before putting the nozzle and the cap back on the gun.
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Mike Marlow wrote:

But Mike, if I put the needle in the back and assemble that way, the needle will not even come close to the end of the nozzle up front. Shouldn't it reach the tip of the nozzle after the handle is released?
Jim
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Push the needle all the way home from the back of the gun. It will reach. Screw the adjusting screw all or most of the way in. You need to get all three components interacting - the needle, the spring and the nozzle. In order for this to happen you have to have the needle in a position where the trigger can contact the larger section on the needle. This requires the adjustment to be turned in some.
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There's a few different models. I've got 3, I'm sure I've got paperwork. Although they should all be close to the same.
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Robert's advice is well taken. I shoot much more with a standard high pressure gun and I don't always stop to think about the different HVLP rigs that are out there, and the differences between them and a conventional gun.
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