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Iwata Custom Micron CM-SB problem!?

Discussion in 'Airbrushes' started by pcDoc, May 29, 2020.


  1. pcDoc

    pcDoc Gravity Guru

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    When I was cleaning my Micron today I realized 2 things, which I don´t think should happen:

    1. When I press the trigger just for air, air seems to go into the cup. Slowly, so it takes a bit till a single bubble builds up, but still that means all the paint is pushed back into the cup.
    2. After cleaning I just sprayed pure water through the gun and I could see that the water is not comming out evenly when the trigger is pulled back just a little and I could here it pulsing.

    Needle and nozzle are as clean as I could get them and they look good. I never dropped them or hit the canvas with it. Water is thinner than paint ever gets, so too thick paint shouldn't be the problem. Tested airpressure from 1.5-2 bar, but the same result.

    I wasn't using the gun for about 5 years now, but while using it I didn't really feel it works bad. The only thing I can think of is the o-ring. Could that be the reason? Or any other ideas?
  2. Kim McCann

    Kim McCann Needle-chuck Ninja

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    air backing up into a cup means that airflow is being pushed back up the needle channel. This is usually from some kind of obstruction in front of the nozzle or a crack or the like in a nozzle or the nozzle not meeting the body right and allowing air in from the air channel.

    I would pop off the nozzle cap and carefully examine the nozzle where it screws in to tje fluid head with a magnifying glass or loupe. Make sure it is screwed in properly (just finger tight), there is no crack or deformation in the nozzle or fluid head.

    Consider using a touch of beeswax or chapstick on a toothpick around the nozzle join to seal off any micro gaps and see if it changes anything.

    I doubt it is the o ring as that doesn't really effect air flow near the nozzle where air is getting into the fluid channel.

    It sounds like the nozzle might have some difficult to see damage and need replacing. But, I'd need to see the brush under magnification to know for sure.

    Air in the cup means air is being blown into the fluid channel, and that means a bad fit between the needle and nozzle, or a crack somewhere on the nozzle or fluid head letting air seep in.

    Probably not an O ring.

    Sent from my SM-N920W8 using Tapatalk
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  3. JackEb

    JackEb The Dragon Hunter Staff Member Admin

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    My first thought is that it wasnt as clean as you thought when you put it away 5 years ago.
    Depending on the paint you were using back then, give the head assemble a good long soak -a day or two wont hurt, in thinner (If you were using urethane) or createx restorer (If you were using acrylic/waterborne paints)
    Use a long bristled artist brush to get right into the nozzle without damaging it, you only need a couple of bristles to pass through the nozzle to ‘agitate’ the paint loose, you could also gently use the needle to help push the paint free.
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  4. jord001

    jord001 Air-Valve Autobot!

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    As Kim and Jackie already said, Its either a bit of paint you think you have cleaned out, not sealing properly or a damaged nozzle. Give it a good check over for damage, try sealing it and if that doesn't work then its got to be old paint still in the nozzle. I think its old paint. Try a shaved down cocktail stick to very very gently ease the paint out. You could also try the nozzle in some stronger cleaning solution to help loosen it, Createx restorer is good, I use urethane thinners/reducer as I have it already. All plastic interdental brushes may work if they are fine enough or an old needle but be careful not to damage the inside of the nozzle.

    Lee
    Last edited: May 30, 2020
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  5. DaveG

    DaveG Airbush Analyst Very Likeable!

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    Air making it back into the color cup, and pulsing are signs of a poor seal between parts, or assemblies. The bubbles in the cup, I am going to guess at the nozzle not having a good seal with the head nase assembly I use chapstick or beeswax to assemble these parts. Pulsing is usually air escaping from around the head base to body seal... again, beeswax of chapstick will fix you up.

    If you have FB, I have an album where I outline my process of dealing with these areas. There is some other stuff that might not be relevant, but click on the pictures, and you can read any info I have attached to them. Hope it gets you going!

    https://www.facebook.com/davegs.airbrush.exploration/photos/?tab=album&album_id=1927007664071479
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  6. erwin de pan

    erwin de pan Mac-Valve Maestro! Very Likeable!

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    What I wonder.
    Can this ring not cause these problems?
    micron  .jpg
  7. SiRoxx

    SiRoxx Party Boy UK Style Staff Member Mod Very Likeable!

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    From what you’ve said damage seems unlikely. Try the beeswax / chapstick on the aircap threads, as well as the nozzle and the head assembly. If you try them one at a time, you should find the part responsible.
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  8. pcDoc

    pcDoc Gravity Guru

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    I was really afraid of you saying it is the nozzle/needle and I need to get a new one... But gentleman you nailed it!

    It was indeed the nozzle cap! It wasn't loose and I couldn´t get it any tighter, but it seems a bit of air came out through the thread. Didn´t have a chapstick or beeswax at hand, so I tried a bit of plumbers tape and that did the job! Both problems solved!

    Thanks a lot for the quick help!!! Ready for the weekend now! :thumbsup:

    Just out of interest as I never had that before, but does that happen often? Is that an Iwata thing? My 10+ year old H&S Evo never had that issue and still runs fine today.
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  9. SiRoxx

    SiRoxx Party Boy UK Style Staff Member Mod Very Likeable!

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    I would think it could happen to any brush. A small amount of grit in the thread could possibly scratch a channel and leak air. Likewise a scratch to the mating surface of either part. Any problems I’ve had with my Iwata’s have always been traced back to something stupid that I’ve done lol
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  10. Electric Cat Dude

    Electric Cat Dude Double Actioner

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    The head gasket (O-ring) May need to be replaced. I would also check the nozzle threads for presence of sealing material. If none remains, you can try placing a little bit of beeswax on the nozzle threads prior to reassembly. I would also suggest inspecting the gap between the nozzle and nozzle cap for the presence of foreign debris that can interfere or redirect air into the paint well of the gum.
  11. pcDoc

    pcDoc Gravity Guru

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    Good, back to the problem... It worked fine and when I put it together today same problem again. After playing around for almost an hour to find the issue, testing chapstick and checking the other threads it is there again this pulsing. Much slower though and visible only when pulling back the needle a tiny bit, so it is definitely muss better than it was some days ago, but not as good as yesterday unfortunatelly...

    I think I didn't answer the questions which paint I´m using: Schmincke Aerocolor and Molotow One4All.

    I don´t think this is the case, but is there any spot I should particullarly inspect for paint? Except the nozzle itself I mean?
  12. Kim McCann

    Kim McCann Needle-chuck Ninja

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    I had a pulsing problem on a CM-C that turned out to be a waxy build up inside the air channels on a fluid head, that I thought was super clean. It only manifested on really small lines. It took a soak in degreaser, and careful clearing with long slim pipe cleanera and then a couple cycles in an ultrasonic, but it all eventually cleared and the brush sprayed like new.

    Maybe a good soak of the fluid head in degreaser or createx restorer would help.

    Check to make sure nothing got inside the air channels in the fluid head air channels

    Sent from my SM-N920W8 using Tapatalk

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