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13 replies to this topic
Posted 21 September 2009 - 06:42 PM
ok i've noticed this problem while shooting Smith Wildlife Colors at around 30psi, a little less than 30.
the problem occurs when i'm spraying small amounts of paint (not pulling the trigger back far) and when the brush is close to the paper i'm spraying on.
what is happening is my brush is making a high pitched squeaking/squealing noise and spitting small amounts of paint.
it did this at low pressures (<15psi) and at high pressures (<30 psi).
do you think this is because of my slightly deformed nozzle or something else?
i'll get a picture of this up real soon so you can see what the spatter looks like.
Posted 21 September 2009 - 07:26 PM
It could be from the deformed nozzle....but it could just as likely be from too thick of paint....try thinning some down and see if that changes anything.
Posted 21 September 2009 - 07:44 PM
here's a picture. you can clearly see the dark specks that shot out all over the place:
i thought Wildlife Colors were supposed to be able to be sprayed right from the bottle without thinning? do you think the problem could have occured in my spraying pressure, or proximity to painting surface?
Posted 21 September 2009 - 08:04 PM
When I look at the splatters vs the finely atomized paint in the letters you painted it doesn't really look like thick paint issues....i'd come closer to saying that its the damaged tip and needle causing your problem.
Follow along with me.....a round needle sealing against the inside a round nozzle...VS....a slightly bent needle thats trying to seal against the inside of what used to be a round nozzle but has now been massaged by some bodyshop expert....chances are good that tip is damaged which allows more air to pass thru that spot that doesn't seal well....so the paint in that spot begins to dries out and collect there.....then as you move the trigger and pull the needle back which allows that tiny spot of dried paint to spit out.....the little high pitched whistles and noises are also indicative of clogging paint at the tip...plus in your case its also most likely tip damage makin some of the whistling noises.
Look at the nozzle under magnification if you can.....I have an old 12x printers loop that I use, but even a magnafiying glass you might have in your desk drawer could allow you to get a better idea of what the tip really looks like....to get good results you need good metal to metal contact around the needle...or you'll get leaks and spitting....period....if those items are good then your paint is too thick.
Edited by 68KingFisher, 21 September 2009 - 08:06 PM.
Posted 21 September 2009 - 11:55 PM
In defense of the body guy I think he was trying to help. :twocents:Just like most of us. I think KF is right the needle is bent and ill bet that the air passage on the air cap has more of a gap on one side than the other this is the whistle. There is no air passing through the needle/fluid passage when all is working right the air comes from around the nozzle and actually sucks out the paint to make the spray pattern. When the needle does not seal right you get sort of a hose vortex action from one sideof the needle rather than an fine mist of paint from around the needle.If it is bad enough the atomized drops actually stick together and produce drops/spatter like you are getting. As far as being in the red you are using some colors have differant viscositys and require some thinning. In a body shop this happens some times and you can straighten the needle out to work well but the margin for error much larger that with an air brush. I wouldn't have tried it.Then again im on the computer trying to help you fix some thing that I have not seen. Buy a new one and call it a good lesson.
Posted 22 September 2009 - 02:14 PM
darn, this is what i thought the problem was, and what i was hoping it wasn't.
one thing that i find a little odd is this problem only occurs when i'm not pulling the trigger back much. any ideas on that?
Posted 22 September 2009 - 02:54 PM
Save that tip and needle assembly for when you want to do splatter back type paint schemes.
Play around with paint mixes until you get one that gives you a consistent splatter effect, and that will be priceless.
Turn a minus to a plus.
Posted 22 September 2009 - 03:17 PM
i just spent about 30 minutes on the phone with iwata customer service and chicago airbrush supply customer service, trying to figure out the parts i need.
in my Revolution BR manual, it lists the .3mm nozzle as part# I7042, and the .3mm needle as I6172.
well after i spoke with the iwata customer service lady, she said that this is a misprint and that the I6172 is actually a .35mm needle for the Eclipse. she said the part i was looking for was I7172.
so i called chicago airbrush asking about these parts, and the guy told me that he had a .3mm needle and .3mm nozzle for the revolution BR, and he told me the part numbers. the .3mm needle was I7173 and the .3mm nozzle was I7042.
on chicago airbrushes website, the part numbers he gave me matched .35mm revolution br parts, but he said that on the package it said .3mm. so the description on the website is wrong.
long story short, i need to buy I7042 and I7173.
Posted 23 September 2009 - 12:18 AM
I think its because your only moving the trigger and needle a tiny amount, and since the paint has to squeeze thru that small opening it begins to build and dry against anything it can get a grip on...like a rough spot...or damaged metal....it continues to build until you pull the needle back enough that it spits itself out....where as, if your shooting alot more paint and moving the needle back alot further, you've got a much bigger opening which allows a larger volume of paint thru the opening so it doesn't get the chance to build up and dry out as easy.....at least thats my theory and i'm stickin to it....lol
I know I have alot more spitting issues when i'm painting the extra fine details....I find it helps to either have new parts in my brush, and in some cases I'll do extra polishing on the needle...the way I see it, it's less area of rough metal for paint to grab onto....look at a factory needle under magnification and you'll see how rough the surface of the metal really is on most needles....A good polishing really makes a difference.
Posted 23 September 2009 - 11:26 AM
different grades of polishing compound....the same stuff you might use to polish out a new finish on a car or motorcycle....most mild compounds from your auto finish care section would work ok....i've even heard of guys using toothpaste.
I go against alot of the guys in that I clamp my needles in my drill and spin them during polishing....alot of airbrushers preach against that, but its always worked for me.
Posted 23 September 2009 - 05:37 PM
yeah i figured since i wasn't pulling the needle as far back this restricted the space for air and paint flow, and made the paint build up faster.
i'm just gonna go ahead and order new parts...
Posted 25 September 2009 - 07:18 PM
got my new parts ordered today. my paints also arrived today.
so now i have yet another delay before i can actually start painting
Posted 26 September 2009 - 05:15 AM
DSV, look at it this way, if the needle and tip is still o.k you have a spare and next time you bend a needle you won't have to wait weeks to fix it - AND - just when you think you have it all covered, check that the nozzle tip, and caps are tight and that the gaskets (if any) are good, because this will give you the same symptoms, usually when the needle is just opened and the tip is at low pressure - daba little soapy water around the caps and you may see some bubbles when you pull the trigger. pete