Spluttering Spray Gun

[silentC]

I'm having problems with my (new) spray gun. It's a cheapo venturi pick-up type. Using it on a 40L compressor with a built-in regulated outlet. I've set it for 60psi but can't get a consistent spray from it. It's almost like the pressure is not constant - but the air on it's own seems steady enough. When I add fluid, it starts to splutter, which results in a patchy coverage. It does this even with just thinners and no finish.

Any ideas? Do you think I need to get a proper regulator?

[ozwinner]

Are you putting enough liquid in the pot?
Ive had them where if you only put a small ammount in the pot it splutters.

Al

[silentC]

That's one thing I didn't think of. I'm putting about 200ml in, which is all I usually put in my old gun. I'll try it with a bit more in it tonight...

[Dean]

Also check all the internal feed lines/mechanisms (in the spray gun) are clean and not partially blocked somewhere along the feed chain.

[journeyman Mick]

Well, thufferin' thuccotasth, my thpray gunth' thplutterin'! :D Thorry, I'll try to restrain myself. ;)
Darren,
if, like Al suggests you need to top it up to get it to work then perhaps the pick up tube is too short (you never know with an el-cheapo). Remove the pot and invert the gun, dribble some thinners down the pick up. If it still splutters the problem is in the gun. If it doesn't then either the pick up is too short, the air hole is blocked or missing or the pick up is sucking in false air. That little air hole in the top of the pot (sometimes with a bit of tube attached) is vitally important. If it's blocked then you are trying to suck paint out of a sealed pot. When working with any fast drying finish (ie lacquer) this hole often gets blocked just from the liquid sloshing around inside during use and getting up in the hole. I usually put my finger over the end of the gun and pull the trigger, this forces air back down into the pot and clears the breather hole. I'ts not a good habit I know, I should probably keep a pin or needle handy to clear it instead.

Just reread your post, 60psi might be too low a pressure for the gun to work properly. I have one gun that performs beautifully at 35 - 40 psi ( a cheapish-$90 copy of a well known brand) and a CIG Arnold gun which requires about 80psi. Put some thinners in and slowly crank the pressure up whilst trying the gun. Obviously you will need more pressure when spraying your finish as it will be thicker than just thinners.

Mick

[silentC]

Well, thufferin' thuccotasth, my thpray gunth' thplutterin'!

Scary isn't it? That's exactly what was going through my mind when I wrote the subject line :)

OK guys, I'll try all that stuff out and see what happens. I did check the breather hole and a couple of other things on the gun. They said 60 psi in the manual but I could play around with it and see what happens.

It's weird, it's like it's pulsing. The finish comes out in spurts, as if the gun is having trouble getting enough air through, which is what made me suspect the regulator might be playing up.

Thanks for the tips one and all.... :)

[Barry_White]

Another thing is your regulator registering correctly.

[RETIRED]

The main cause of "spluttering" is................

The nut where the the needle runs. It comes loose, air leaks through the seal and you guessed it, splutter. Tighten it and in most cases problem fixed.

HTH.

[ozwinner]

The main cause of "spluttering" is................

The nut where the the needle runs.
I thought you were going to say, the nut on the end of the gun!!!!!!!! :D

Al

[echnidna]

or the loose nut on the keyboard

[RETIRED]

HMMMM Sometimes:D

[ozwinner]

or the loose nut on the keyboardNow come on echnidna, you need to have a higher opinion of your self. :D

Al :)

[morry]

some guns use a leather/fibre washer to seal the needle to the outside atmosphere with a small cupped nut to secure it. A drop of oil on the leather usually works and snug the nut up just enough so the needle still moves when the trigger is depressed. This problem drove me nuts for ages until I finally deciphered the "Engrish" instructions.

[silentC]

The nut where the the needle runs

I will f#$%ing kick myself if that's what it is. I took that off to clean it and noted to myself at the time that it was a bit tight.

Maybe I should use some teflon tape on it ;)

[silentC]

BTW You're all so bloody funny :D:D:D:D

[soundman]

another piont that can be a problem with the "arnold" clones is where the front half of the head meets the back.
there is a threaded sleve that holds the two together. you tighten it with an alen key accessed thru the hole where the needle & its adjusting stuff comes out.
these also break sometimes when dropped.

the giveaway for this one is the pot seems to wobble but closer inspection shows the whole needle cap assemble is wobbling on the rest of the gun.

cheers

[RETIRED]

Darren.

Is it fixed yet? We are all waiting with bated breath. :p

[silentC]

Nah, haven't had much shed time this week and I'm off on a three day walk tomorrow. You'll have to hold your breath until next week :eek:

I wonder how many PSI is tied up in all that bated breath :p

[silentC]

I tried all those suggestions but no go. Is the thing a dog? It's like the gun isn't getting a consistent air flow. If I sweep from right to left, what I end up with are regularly spaced patches of finish and the panel looks like it's been hit by a paintball gun.

I've got another gun but it has the wrong connector and the thread size is different. I'll have to try and find a male connector with the correct thread and give it a try.

Might have to go back to the old CIG Easy Sprayer... :(

[soundman]

ARRGH
dont do that

get down to your local tool shop & grab a "Star S770" for a round $100.

they are a great gun and very reasonably priced.

just a thaught have you given the dog a full clean.

I have one of those cheap arnold i use for glue & it was spattering a while back, a full dismantle & clean sorted it.

Oh have you checked the screw in seat behind the air cap is sealing to the body.

cheers

[silentC]

I finally got around to checking this out. It turns out that the nut that the needle passes through where it comes out to the trigger was loose. I think this is the one was talking about but I thought he was talking about the brass nozzle at the front of the gun, so of course I never checked it. Is that the one you were talking about soundman? Would help if I knew what stuff was called :rolleyes:

Anyway, I've tightened it up and it made a big improvement. It still varies a bit but it's useable now. One thing I noticed when I disconnected the gun, there was a fair bit of moisture inside the hose. Could this be causing a problem?

[Sprog]

One thing I noticed when I disconnected the gun, there was a fair bit of moisture inside the hose. Could this be causing a problem?

It will cause a problem with the finish, get a moisture trap fitted, the inline ones are not too expensive. :)

[RETIRED]

I finally got around to checking this out. It turns out that the nut that the needle passes through where it comes out to the trigger was loose. I think this is the one was talking about but I thought he was talking about the brass nozzle at the front of the gun, so of course I never checked it. Is that the one you were talking about soundman? Would help if I knew what stuff was called :rolleyes:

Anyway, I've tightened it up and it made a big improvement. It still varies a bit but it's useable now. One thing I noticed when I disconnected the gun, there was a fair bit of moisture inside the hose. Could this be causing a problem?

Yep! :)

[Kris.Parker1]

Try pulling the gun apart and checking all the o-rings. Even look for small air leaks in the hose by putting the hose in the bucket and look for bubbles.

Cheers

Kris