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DIY FogBuster

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  • Ray Livingston
    Today I re-made (for the third and final time!) my home-made FogBuster. I am *really* happy with the way this one works! The previous two worked well, but had
    Message 1 of 1 , Sep 29, 2008
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      Today I re-made (for the third and final time!) my home-made
      FogBuster. I am *really* happy with the way this one works! The
      previous two worked well, but had problems with the sensitivity of
      the needle valve adjustment, and it was difficult to completely shut
      off the coolant flow. What I've learned from this is that making a
      precision needle valve is a LOT harder than it looks.

      I've posted a few photos in the "RayLs FogBuster" photo album:

      Photo 1 shows the coolant reservoir/pressure tank. This is
      simply a $20 household water filter canister, available from pretty
      much any home center or plumbing supply house. It has regulated, at
      20-30 PSI, air coming in one side of the top, andn two outlet hoses -
      one comes off the very top of the canister, so it gets just air,
      while the other is connected to a hose that runs down to the bottom
      of the canister, so it gets only coolant.

      Photo 2 shows the nozzle assembly. The two hoses from the
      coolant tank connect to it, and the needle valve assembly is part of
      it. The nozzle itself is a 7" length of 1/8" OD brass tubing,
      available from any hobby shop. At the outlet end, a 3/4" piece of
      3/32" brass tubing is Loctited in, to provide the reduced diameter
      orifice as specified in the FogBuster patent ( see
      http://tinyurl.com/3oh35l ). The air line feeds directly into the
      nozzle tube, while the coolant line feeds into a drilling that runs
      into the needle valve drilling. The needle valve drilling runs all
      the way down to meet the nozzle tube drilling. The nozzle tube has a
      small cross-drilling, lined up with the needle valve drilling, to
      admit the coolant.

      Photo 3 shows the parts of the needle valve assembly. The
      housing is a simply 1/4" brass compression coupling, from the
      hardware store. The center bore is tapped 12-24, for the needle
      valve itself. The needle valve is machined from a piece of 1/2"
      brass all-thread. On this one, I made the needle itself a separate
      piece, but it will be part of the brass on the next one. The shaft
      is sealed by the O-ring, and the little nylon "top-hat" just
      compresses the O-ring to obtain a good seal. The needle "seat" is a
      piece of 1/8" diameter nylon, with a 0.040" hole through the middle,
      that is pressed into the bottom of the needle valve drilling in the
      aluminum valve body.

      This gives a *excellent* control of the coolant flow rate, from
      just dry air, up to a raging torrent of coolant, with about one turn
      of the needle valve. The valve itself is nicely air and water-tight,
      and works very smoothly and easily, making precise setting of the
      desired coolant very quick and easy. Due to the small nozzle
      diameter, the airflow requirement is modest (I'm running on a $79 air
      compressor), but it provides excellent cooling, and excellent chip

      Ray L.
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