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Ideas for special pump, peristaltic maybe?

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  • Ideas for special pump, peristaltic maybe?

    My 900x2000mm CNC router table is being used to paint signs and such like.

    The current process is less than ideal and involves using the CNC to draw the outline of text etc using paint pens followed my manually colouring them in.

    The idea is to convert to automatic brush or paint jet/spray. I am concentrating on the brush idea unless someone can tell me how to make a suitable spray or jet.**

    The brush will be a bundle of parallel fibres in a tube with paint forced in as required. I could use a syringe but maybe a peristaltic pump.

    The pump has to be able to deliver the required amount of paint, it must be easily washable and of course it must be something I can make.

    Any comments?


    ** tell me about fuel injectors, could they be used as paint jets?

  • #2
    Air brush??
    “I know lots of people who are educated far beyond their intelligence”

    Lewis Grizzard

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    • #3
      Originally posted by Dave C View Post
      Air brush??

      Maybe, certainly sound interesting but could I make one work vertically?

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      • #4
        I don't see a problem with it. A good unit can paint a pretty fine line, and you may even be able to get it to do your fill in coloring.
        “I know lots of people who are educated far beyond their intelligence”

        Lewis Grizzard

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        • #5
          Originally posted by Dave C View Post
          I don't see a problem with it. A good unit can paint a pretty fine line, and you may even be able to get it to do your fill in coloring.
          I think most air brush require a finger on the button to control the air?

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          • #6
            Originally posted by The Artful Bodger View Post

            I think most air brush require a finger on the button to control the air?
            You just need to hook up a RC car servo to it so you can feather it on the fly.

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            • #7
              Originally posted by The Artful Bodger View Post

              I think most air brush require a finger on the button to control the air?
              Would that finger function be controlled by a solenoid operated by the CNC that controls paint/no paint part of the program?

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              • #8
                Air brush with a siphon tube running to a paint jar, tape down the switch on the brush and put a solenoid on the incoming air line
                Works in my head at least

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                • #9
                  Peristaltic pumps are not hard to make, and are dead easy to clean. Just a tube of lab grade flex tubing, in a housing, with a couple of wheels on an arm to do the forcing through. I've made some parts for them for a guy know, who uses them to pump the correct amount of conformal coating for assembled PC boards.

                  He 3D printed the housings, but had me make drive rollers for them
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                  Keep eye on ball.
                  Hashim Khan

                  Everything not impossible is compulsory

                  "There's no pleasing these serpents"......Lewis Carroll

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                  • #10
                    Originally posted by J Tiers View Post
                    Peristaltic pumps are not hard to make, and are dead easy to clean. Just a tube of lab grade flex tubing, in a housing, with a couple of wheels on an arm to do the forcing through. I've made some parts for them for a guy know, who uses them to pump the correct amount of conformal coating for assembled PC boards.

                    He 3D printed the housings, but had me make drive rollers for them
                    If I’m not mistaken they can also be very accurate as far as dosing is concerned.

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                    • #11
                      Further investigations indicate the peristaltic may be the route to go. I looked at old type diesel and modern common rail petrol injectors but neither look to be easy and certainly not as easy to clean as the peristaltic pump.

                      Now I need to decide if I want a brush type nozzle, a spray or just drops of paint on the surface.

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                      • #12
                        OK, my eyes have been opened somewhat regarding airbrushes but I am uncertain on a couple of points....

                        I see the better ones have a double action on the button, press to start air and slide to start paint. This might be a bit complicated to arrange with an electric control from the CNC system. Maybe I could leave the air flowing and just start and stop the paint?

                        The other uncertainty, will the airbrush operate OK vertically? I guess I might have to arrange or modify the paint supply somewhat.

                        Thanks

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                        • #13
                          You might consider making yourself an oversize ball point pen to be used with paint. Depending on the thickness of the paint you might have to pressurize the paint container with a very slight psi of air. The ball could be a ball or a roller. The ball would be easier to implement as you would not require any tangential motion. A roller applicator could be built with the same bearing swivel as a Donek drag knife. That would not require you to have any motorized tangential axis. An air cylinder could be your Z axis with a depth stop.
                          Location: The Black Forest in Germany

                          How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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                          • #14
                            Originally posted by Black Forest View Post
                            You might consider making yourself an oversize ball point pen to be used with paint. Depending on the thickness of the paint you might have to pressurize the paint container with a very slight psi of air. The ball could be a ball or a roller. The ball would be easier to implement as you would not require any tangential motion. A roller applicator could be built with the same bearing swivel as a Donek drag knife. That would not require you to have any motorized tangential axis. An air cylinder could be your Z axis with a depth stop.
                            That certainly is an idea worth investigating and maybe I can find one already made in the deodorant section at the supermarket!

                            Meanwhile, I have ordered an airbrush....
                            Last edited by The Artful Bodger; 01-22-2022, 02:07 PM.

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                            • #15
                              I would think that using air pressure would be easiest, and solenoid operated valves next to the spray nozzles.

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