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gas powered air brush air compressor

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  • #16
    Originally posted by anotheridiot View Post
    Why is this based off of an air compressor and not just a vacuum pump? much fewer moving parts and slower rpm requirements.
    1) it's what the dentist wants.... never discount this, these people are risking their lives and not getting paid to do it.... even if it's a better idea, that better idea could result in the dentist saying "nope"
    2) because it's hard to fill an airplane tire with a vacuum pump - prior to this, they used a 12v air compressor I sent them (which got stolen)
    3) that said, volume and the need for oil in a vacuum pump. they do use the air compressor to create suction.
    4) weight - again.
    5) few parts? on the vacuum pump are fletches - each of those can wear, so I'm not sure where you get fewer parts.... two pistons, two reed valves is this air compressor.

    but even if you disagree... go back to number 1. and if next week the dentist gets a brilliant idea for a vacuum pump compressor - I'll build that too.
    Doing it all wrong since 1966

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    • #17
      Just asking, since its just being used for suction. I must have missed the airplane tire filling need in your earlier posts. Might even be a deterrent for theft since who wants a vacuum pump? I would think this gas driven deal is going to have a bigger bullseye on it.

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      • #18
        More "Sorry, can't help it" response from me.

        My vacuum pump weighs quite a bit .. not sure what that evil lady uses at the dentist office, but I'm betting it's more than 2.5 cfm too. I do *not* want her in my face with something designed to pull a medium vacuum for an AC system. haha.

        If we're talking primative, what about this thing? Sucks one side, blows on the other...

        Flying south, with a flock of bird dogs.

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        • #19
          Originally posted by Beagle View Post
          More "Sorry, can't help it" response from me.

          My vacuum pump weighs quite a bit .. not sure what that evil lady uses at the dentist office, but I'm betting it's more than 2.5 cfm too. I do *not* want her in my face with something designed to pull a medium vacuum for an AC system. haha.

          If we're talking primative, what about this thing? Sucks one side, blows on the other...

          you can use a vacuum to run air tools... why would you do that? I dunno - I'll have to see what happens with my vacuum pump (you know, the air powered one) tonight.

          I was surprised that such a small compressor could run air tools - that said, it's what they want; it's what they get. The weedeater should be here Thursday, so I'll know soon enough how it works.

          coincidentally, I just told someone that the welder that they bought was so old that it replaced bellows....
          Last edited by SuperBuickGuy; August 3, 2020, 11:06 AM.
          Doing it all wrong since 1966

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          • #20
            Originally posted by SuperBuickGuy View Post

            you can use a vacuum to run air tools... why would you do that?.
            I can think of one really good reason... if you run a grinder on a vacuum instead of positive pressure, it will add the metal you just accidentally removed back. I don't know if that will work with teeth though.

            Flying south, with a flock of bird dogs.

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            • #21
              Originally posted by Beagle View Post

              I can think of one really good reason... if you run a grinder on a vacuum instead of positive pressure, it will add the metal you just accidentally removed back. I don't know if that will work with teeth though.
              *snicker*
              bonus!

              that would save on filling material for the villagers.....



              now you own me a monitor....
              Doing it all wrong since 1966

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              • #22
                SBG is TOO polite. Not to say an idea sucks.....
                My hobby is needing a hobby.

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                • #23
                  Originally posted by RockJustRock View Post
                  SBG is TOO polite. Not to say an idea sucks.....
                  probably should mark that day on your calendar, it doesn't happen often... matter of fact, I can't remember once....
                  Doing it all wrong since 1966

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                  • #24
                    Originally posted by SuperBuickGuy
                    small engine electrical question... do you think the magneto on a 4 stroke gas weedeater motor has enough 'extra' juice to run a servo?
                    They don't normally have charging coils, and the CDI is usually self contained... if it was like a bike rotor, you could probably add a charging coil but I think it's going to be external and that could be a treat to work out.

                    Pull the shroud and show us what you have to work with?
                    Last edited by Beagle; August 6, 2020, 12:20 PM.
                    Flying south, with a flock of bird dogs.

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                    • #25
                      Servo? As in R/C servo? Battery?
                      My hobby is needing a hobby.

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                      • #26
                        I think you just pressed off a potential generator stator... ?
                        Flying south, with a flock of bird dogs.

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                        • #27
                          just for giggles, I'd put the Milwaukee drill on that compressor and see if it would spin it.
                          Flying south, with a flock of bird dogs.

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                          • #28
                            cool stuff. thinking a generator motor is the kind that is used to spend hours running at a time. I got this little radiator I was going to make a welding torch cooler out of, all aluminum like 8x8x3 or so if you end up needing to go water cooled. Probably weight as much as the fluid you would need in it.

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                            • #29
                              You may already know all this, but I'll throw it out there anyway. Speedaire used to do this with small compressors from before my time. Northern tools and HF both have gas compressors that do pretty much the same thing. I don't think it will answer the governor question though. The unloader basically pulls the throttle control back to idle, which lowers the spring pressure against the governor arm.

                              The Honda up there has cam driven centrifugal weights for a governor and a variable spring pressure on it from the throttle "lever" setting. When you set the throttle lever for high speed, or you put a load on it, the throttle blade goes wide open and stays wide open until the governor pulls it back and finds a balance of RPM to spring tension.. At idle, the governor doesn't have to pull as hard on the spring to close the throttle blade and it settles into it's happy balance of weight v. spring tension, stable RPM. Light loads recover quickly so it may never get to full throttle before the governor pulls it back. There isn't any real connection between the unloader and the actual throttle shaft, throttle control is just a change of spring pressure against the governor, who has the actual connection to the throttle shaft.

                              If you let your whacker motor run wide open, I'd venture a guess at 7000 rpm or more. If that's within spec, cool.. but that's what I meant on page one about I'll take a wait and see on the governor aspect.
                              Last edited by Beagle; August 8, 2020, 06:31 PM.
                              Flying south, with a flock of bird dogs.

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                              • #30
                                Right - hence "unloader" ... I think we're pretty much on the same page. I'll be surprised if it has a governor though. The string length on a weedeater will usually limit rpm. Where I'm mostly going with that question is how well the compressor will handle 7000 rpm or so?

                                Random - When Honda first started bringing 110 cc OHV mower engines into the States (A GM design fwiw, who owned Briggs, who said it wasn't feasible) 21 inch Mowers were supposed to be limited to about 3100 rpm for OSHA blade tip speed requuirements. The unintentional governor on those motors were the valve keepers. About 4100 rpm for a few minutes and it'd pop one. Non-interference engine so not that big a deal, but the guys who used to tie a string to the governor rod learned not to do that any more.
                                Last edited by Beagle; August 9, 2020, 04:44 AM.
                                Flying south, with a flock of bird dogs.

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