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Adjusting AB Action

Discussion in 'General Airbrush Discussion' started by Tocean, Jun 24, 2018.


  1. Tocean

    Tocean Needle-chuck Ninja

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    I've been using my HP-BCS for a while now and feel I've just started to get to know it, wondering how much adjustments I could make for the action, I've noticed I have to pull back on the trigger further then I want to get the paint out, I've got use to this now but it does seem kind of "loose", is there a way to tighten the action up? The spring? Or is it just how the airbrush is and I need to get use to it.

    Also what is the function of that little screw on the bottom back that always falls out?

    Thanks, trying to fine tune some things, wondering if I can adjust the AB to me or do I need to adjust myself for the AB:cool:
  2. RichardH

    RichardH Elite Member! Elite Member! Very Likeable!

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    What air pressure are you set up and using?? Except for the paasche brushes, I've never used a hp-bcs but it might just be the pressure adjustment that is needed. Also thicker paint would make it be slower and you would have to pull the trigger back farther to get it to flow.
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  3. DaveG

    DaveG Detail Decepticon! Very Likeable!

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    Having to pull the trigger back and waiting for paint flow to start is not actually an adjustment that needs to be made with the brush. It can be in indicator that the paint can, or should, be reduced some more. About the only end user adjustments on most AB's are made by changing out springs on the needle and the air valve to either soften or stiffen the feel... most shoot for softer.
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  4. Tocean

    Tocean Needle-chuck Ninja

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    I'm talking pulling the trigger back ever so slightly, might be my reduction but sometimes I over reduce the goldens and it feels the same.

    Ok so maybe I need to try out a new spring, not sure why I want a stiffer feel, maybe because I'm use to the big clunky suction feed hvlps.

    Got a feeling it's something I need to adjust to, I am feeling how the gun wants to work(like it has it's own mind) how close you put the needle, pulling back the action to the speed of movement - I guess it's mastering these 3 things together to get total control.
  5. RichardH

    RichardH Elite Member! Elite Member! Very Likeable!

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    :thumbsup::thumbsup::thumbsup:
  6. J000seph

    J000seph Detail Decepticon! Very Likeable!

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    The first thing I would suspect is like others stated above. Either paint is too thick, or air pressure is too low.

    But, if it’s not for those reasons, I think there may be other factors as well possibly. Cleaning my airbrush better has solved most of my technical issues, so I rule that one out first when troubleshooting. Maybe others can chime in, but I think symptoms similar to what you’re experiencing can sometimes be:

    1. Loose needle bearing
    2. Clogged siphon bottle vent hole
    3. Airbrush air leak

    Do you have the needle tensioner tightened all the way in? How long has it been since last adjusting needle bearing? Have you checked it for air leaks?
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  7. DaveG

    DaveG Detail Decepticon! Very Likeable!

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    Joseph is not wrong, as there ca always be other factors that effect the way a brush works - I generally refraining from going there first though, as new users tend to get WAY carried away trying to clean their brush, rather than just trying to learn what makes it happy.

    Out of the possibilities listed, I would rule out the needle packing straight off, as that is located behind the paint supply, and has no effect on the process of paint delivery to the surface. It can actually be removed altogether and the brush will work the same... I have lots of older brushes that don't have one at all. The possibility of paint then getting into the trigger area will pop up, so do keep it in ;). Adjust when and if you start getting paint into the trigger area... as that is all that it is there for.

    Excellent point about the vent hole in the bottle. This is something that is really easy to overlook! As paint is being drawn out of the bottle, air needs to be drawn in to avoid creating a vacuum condition in the bottle. Occasionally poking a pin into the hole if they are not emptied and cleaned regularly may be a good idea. As for air leaks, drizzle cleaning fluid or mildly soapy water around the head base while releasing air. If you have bubbles or foam forming around the seams, you have an air leak. Common in most brushes, worse in some. A little bee's wax or chapstick applied to the threads of the brush body before screwing the nozzle cap on should cure the situation. An air leak here will not necessarily degrade a brushes performance, but can, so why not eliminate it.
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  8. Robbyrockett2

    Robbyrockett2 Air-Valve Autobot!

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    The little screw on the bottom back....sounds like you've got the old style brush.
    i think it holds the chuck in place since the rocker is separate?
    I'm guessing here but i think the chuckng guide has a slot for it and if its not in the slot then your guide could roatate and cause the action to feel rough since the aux lever wouldnt mate right with the chucking guide????

    Also out of curiousity @DaveG , I know its basically un necessary on gravity feed but doesnt the needle packing need to seal on siphon feeds in order to keep the vacuum needed to pull paint up?
    Seems like it would suck in air and make it spit every so often

    Everytime i've had to pull back too far has been because of crud on the inside of the nozzle, talking a difference of pulling back like .5mm vs pulling back like 1-1.5mm to get initial paint flow. Something like that idk really small amounts though.
    Last edited: Jun 24, 2018
  9. Robbyrockett2

    Robbyrockett2 Air-Valve Autobot!

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    It may just keep it from rotating so you can screw and unscrew the chuck nut....idk it does have a slot in the chucking guide that mates with it though.
    As dumb as it may sound, i'm assuming you have already played around with tightening or loosening the spring guide to adjust the feel?
    Last edited: Jun 24, 2018
  10. DaveG

    DaveG Detail Decepticon! Very Likeable!

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    In practical terms, there is no difference between a side feed, and what you refer to as a siphon feed brush. Paint is drawn from the bottom of the color cup on a side feed, which is below the feed hole, by the exact same action on both style brushes. The model A side feed you will soon have your hands on, has no needle packing, and trust me, it works brilliantly. The original Iwata HP-BCS was designed without a needle packing, which was added in later production runs. Looking further back in history, the Wold A2N, which offers feed holes in both the bottom of the brush, and the side, as well as the Model J(n), and others, have no needle packing.
  11. Robbyrockett2

    Robbyrockett2 Air-Valve Autobot!

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    Yeah , i had no idea...only used the siphon feed HF brushes, which i just threw away if they had any issues. I guess atmospheric pressure pushing the paint up takes less of a pressure difference than getting air to bypass the needle?? IDK interesting though.....

    On the other part, since i was making guesses
    What purpose does the chucking guide screw serve?
  12. DaveG

    DaveG Detail Decepticon! Very Likeable!

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    that simply holds a collar in the brush body, as allows the screw to also keep the chucking guide from turning while under tension from the needle spring... screw point fits into a channel int he chucking guide.
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  13. erwin de pan

    erwin de pan Needle-chuck Ninja

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    I have also wondered for a while what that screw is for.
    I wanted to remove the ring in the body. So that I can replace it for a new style chucking guide.
    But the ring is stuck. Think they press those into the body.
    And the screw is only for extra safety.
  14. Tocean

    Tocean Needle-chuck Ninja

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    Thanks for the replys, I use cups so no clogging in the bottle but I do have a leak at the cap I'll try some teflon on the threads. This Iwata was given to me years ago so I have no idea how old it is. I did lose that dang screw(some say in my head a long time ago), it was always falling out but I may of swept it up and threw it out this time, I haven't noticed any difference in spraying.

    May be time to just get a new BCS(and a couple other) and keep this one for a backup.

    [​IMG]
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  15. Robbyrockett2

    Robbyrockett2 Air-Valve Autobot!

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    According to the date code chart it was manufactured february of next year LOL
    going by the pattern though i would guess its actually Jul 2002
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