Siphon feed airbrush not siphoning?

jkj2000

Young Tutorling
I'm an airbrush newbie, so apologies if the fix to this is obvious. I picked up a Master S622 from tcpglobal, so not exactly an Iwata, but it gets decent reviews for a starter brush. And since I'll be spraying some single stage urethane with it, the 0.8 tip had a big appeal.

However, I can't get it to work and am not sure why. The air comes out fine but even when spraying with water out of the bottle nothing shoots out.

I've disassembled it and nothing appears blocked. My compressor works fine with my gravity-fed airbrush, and on this new one the needles and tips appear to be ok as well, they open and close when I move the trigger, nothing appears bent, all parts look to be machined correctly and the gaskets look good. Just nothing comes out when I pull back on the trigger. I have the pressure set at 40psi.

If I put my finger over the tip and pull back plenty of air goes back into the bottle, bubbles like mad. I've tried everything, even spraying without a tip, and nothing doing. I've checked the air and fluid passages and they seem fine.

If I hold the bottle tightly in there some liquid will spit out in a spray, occasionally. I'm not sure if there's a vacuum issue with the bottle, but it's the one that came with the unit so it's not a beat up one, and it looks good to my eye. I've tried tightening the bottle's lid, loosening it a bit, just to see if any adjustment makes a difference and it hasn't.

Does any of this ring a bell and are there other troubleshooting steps I can try? Thanks a bunch.
 
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Hey there, yes, common problem, there are plenty of threads dealing with this. Make sure the little hole in the top of the bottle is clear. Is the needle chuck screwed on tightly enough - so the needle is moving?

While the others are answering how about popping along to the introduction section and saying hi for us? So much nicer when we know a bit about the person... what you paint, experience, what part of the world are you in, equipment, that sort of stuff.

Here is the link. http://www.airbrushforum.org/introductions/

Cheers Mark
 
Yeah, I had that problem and I totally overlooked that little breather hole on the bottle. It did the same thing to me. Here is a pic of my bottle with a toothpick stuck in the breather hole to show where it is.... jeeesh I need to clean my bottle. Since I got my gravity feed, I don't get much use of my Neo

20160908_163533.jpg
 
If it won't spray water but sprays air,most likely you have a leak somewhere and it's sucking air from the leak,and easy way to find it is to pull off the bottle and drop your air pressureally down around 10 psi and get a pan of water that you can put the brush in ,while holding a finger over the hole the bottle fits in back flush the brush and look for bubble around the nozzle area if you see any it's leaking at that point,to fix the leak take the part that's leaking apart and put a small amount of bees wax or chapstix on the threads and put it back together and try again till you get all the leaks stopped
 
Thanks everyone. Mark, I'll do an introduction soon...
I tried the chapstick trick and that didn't seem to do much, so I took it a step further and wrapped a little teflon tape around the head threads, and that did help...at least, now it 'pulses' water, not really a steady stream however.

The compressor I'm using at the moment is a low-end oiless wonder that is throttled to 40psi max. I have an oiled one that I need to get a new check valve for (reminds me, I need to post a thread about that as well) but in the meantime I can try with my 25 gallon compressor in the garage, throttle it down to, say 60 psi and see if that helps.
 
If it sprays great at a higher pressure then your paint to thick,what paint are you using? And are you reducing it at all?
 
What is your air pressure when the trigger is completely pressed on and the gun is consuming air? That size gun consumes quite a lot of air, so I'm guessing the pressure drop is huge. Maybe too much for it to spray. On the other hand it shoud spray water even with low pressure.. So it's a clog or a leak. Fill a bucket with water put the gun in there leaving only the tip on the surface, if it sprays then it's a leak. Don't spray your self in the eye.
 
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I have not seen what paint are you using ?
What PSI are you spraying at?
and have you soaked the nozzle to make sure you do not have a huge build up of dried paint ?
 
I think, the problem isn't a problem:) Tighten the nozzle head a bit more, that big "nozzle" I mean. Fluid nozzle thus will find its place. Everything is gonna be OK then.
Bubbles say that nozzle isn't tightened.
BTW, it's my favorite chinese model. The only one among chinese AB models I owned, which I left for myself. I've got good japanese ABs, and can say this model is good at work and good choice to start ABing if you can't afford or don't want to spend your cash on iwatas etc.
 
ya already answered it for yourself..nozzle is leaking. Not sure on that model but check if it has an oring, that oring has likely been squashed or if its a face to face seal some crap in there likely causing it not to seal. if it sucks in to much air into the nozzle it breaks down the venturi and thus wont suck anything through to the pressure variation being higher in the head. common issue with cheaper brushes is the threads are not quite machined to the same clearances as higher end guns and any stripping down often wears it further..I dont like teflon tape on brushes personally but sounds like you need to sort it in that area..
 
Thanks for all your advice. I've tried it again with the teflon tape and checking the threads, and am still having the same trouble. I made a video of the airbrush-in-a-bucket trick, to show the problem I'm having. I hope this helps with the diagnosis. and thanks for watching and/or diagnosing.

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See how its bubbling also from the seam between your nozzle and the head assembly (likely where ya put that tephlon and where there is a face oring style seal..) Still think thats the area of issue. It may be you think its sealed but I dunno..The only other thing that generally causes that is a blockage in the actual nozzle/head assembly itself. many of us suggest you dont use tephlon tape. that tape could have made the issue worse or actually pushed some of the teflon down the thread and in effect is pushed into the head assemble from behind potentially causeing a worse block, plus tephlon needs to go on in a specific way, if you put to much on it can cross the threads really easily. Do a test...Small cup, soapy water. Dip the airbrush in and then blow air through (Like checking for a gas leak) If it bubbles badly on that seem (IE forget the bubbles coming back out the the syphon) that head assembly thread and how its sealing is the problem. (This is a common issue in cheaper brushes because the threads wear fast and the orings arn't worth at times even being there after they have been flattened out a couple of times..

To fix it..Take of the teflon tape look at the threads closely with a magnifying glass, are they really flat or cross threaded? If so its an issue and throw the gun away LOL, if the threads are fine use a chap stick or vaseline and load that thread up but keep the vas away from the rear hole of the head assembly (No puns guys LOL, know you all well), replace the oring if possible and see if you can find one that fits a bit better, i find the orings in some guns just cheap crap. Before putting it back together, make sure all breath holes are clear and unobstructed, again a close look with a magnifying glass with a light behind will show those holes clearly..Also whilst there with your light and magnifying glass, check the actually nozzle has no cracks or that its not to badly flared. If so replace it..Then put it back together, when you seat your nozzle give it another try first at finger tight, do your test again..If still leaking, carefully, oh so carefully nip it up with some pliers or the light and when I say nip it up, a fraction of a turn beyond finger tight is what I mean, make sure you loosen your needle before doing so. Check again...And if none of the above work..your gun is ******* ;) The issue though isnt your syphon feed bottle, especially if it does blow back like that without it even attached, and hate to also say it but this is a problem with some cheaper brands, they can be hit and miss off the shelf..but still think its just not sealing the head assembly properly and if it is sucking air in their it f's up the pressure difference and the air will find that a barrier and then head to the area of least resistance..kinda like electricity..
 
Thanks, I'll try the soapy water test. Before I do, I did try a rather unscientific test...I put my mouth on the siphon opening and blew into it.

With the needle in place, and the teflon tape removed I couldn't hear or feel any air escaping from the seam. If I pulled back on the needle then air came out the nozzle, just as you'd expect.

I made sure when I put the teflon tape on that I wasn't blocking any holes. I do have several HVLP guns for automotive and other painting and have used teflon often enough in the past, and was careful to put just on what I needed....the threads on the nozzle and heads seem to be good, no cross-threading that I can tell. I do wonder if the big O-ring is wide enough for this job, truth be told.

I'll give the soapy water a shot and do another round of adjustments. If that doesn't work I'll call TCP global for a replacement.
 
OK!
Don't use teflon there. Rubber o-ring should be enough. The purpose of that sealer is not to have air leak in the place. It doesn't work for the nozzle. Nozzle should stay in that conic hole firmly, then you will have no air going back inside the body.
The problem is real strange for me, as I had 8 ABs of this model, and haven't had any issues with them ever.
It seems to me that it's tightening that's required there, but not to the extent of having the threads broken.
Try another nozzle maybe... If I'd hold the brush in my hands, I'd tell the problem.
 
Hi Vladimir,

I tried a couple of different nozzle / needle combinations originally, but will give that one more shot as well. I agree, this is a strange one..
 
Have you tried to examine how the nozzle fits the conic hole inside the body? It must be perfect.
And when you tighten air head without the o-ring, there should be smallest space between body and air head where o-ring is installed, as I remember. The function of the head to hold the nozzle in place. And provide air to the air cap, but we talk about nozzle issues now.
Maybe you'd shoot macro picture of the insides of the air head?
 
Thanks, I'll try the soapy water test. Before I do, I did try a rather unscientific test...I put my mouth on the siphon opening and blew into it.

With the needle in place, and the teflon tape removed I couldn't hear or feel any air escaping from the seam. If I pulled back on the needle then air came out the nozzle, just as you'd expect.

I made sure when I put the teflon tape on that I wasn't blocking any holes. I do have several HVLP guns for automotive and other painting and have used teflon often enough in the past, and was careful to put just on what I needed....the threads on the nozzle and heads seem to be good, no cross-threading that I can tell. I do wonder if the big O-ring is wide enough for this job, truth be told.

I'll give the soapy water a shot and do another round of adjustments. If that doesn't work I'll call TCP global for a replacement.

Blowing thru isnt a bad test but you cant emulate the pressures unless you blow real hard LOLOL, even if you felt a light leak by blowing thru its what it does to the venturi (IE The engine of the brush) thats the issue...Did a slight nip help? and are you sure you havent mixed heads up..Is it perhaps wrong needle with wrong nozzle issue. few of us have done that before LOL and common on brushes with various size options..though not sure if the master you have is that kinda brush..Oring cld be an issue but more likely would focus on condition of needle and nozzle seating as mentioned above, the head assembly threads and basic cleanliness...If all those are fine it shouldnt backflow. PS Orings are designed to be squashed to create a seal, not massively squashed but some pressure needs to be on it, I have seen heaps of cheap orings that over squashed the first time there used and being cheap they dont return to full "new" size (PS Chcuk it in some thinners for a quick bath, that often swells them again on cheaper orings, leave it to long though may not be there when ya get back LOL, pending on quality of the rubber used.. and are flat and no interference occurs on the needed faces or threads, it may be playing a part in the issue so try that light nip before anything else, just dont forget to back of your needle and dont over tighten.Also you mention painting or wanting to paint uros with it..Is this brush designed to actually take uro's? Not all are and cheaper brushes can be killed quickly with uros or harsh cleaners.Hope ya get it sorted...:)
 
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