On Friday, February 22, 2002 at 6:47:17 AM UTC-5, Karl Townsend wrote:
I've used a mister for many years on both lathes and mills. I hate the mess
of flood coolant leaking all over the floor and mist cooling gives about 90%
of the benefit. The major problem with mist cooling is fogging or atomizing
the coolant so fine it floats around in the shop. Since I'm running a
machine many hours a day, I've gotten real sensitive to the fog - it gives
me a sore throat.

Anyway, I read about a low fog mister called a HenchForth Fog Buster here on
this NG. A fellow had obtained a copy of the patent for this unit and made
his own. So, I did the same. This unit was better, but still a slight fog or
smell of coolant would be in the shop. But,it gave me the idea of how to
build a better one. This unit works so well, you can't tell its on - no sign
of fog or odor of mist.

The key to operation is in the relative pressure of the coolant and the
supply air pressure. A standard mister has the coolant unpressurized and
uses 40 - 60 psi air. The Hench unit pressurizes the coolant container to
the same pressure air as the air line. This unit uses a higher air pressure
for the coolant than the air line.

A short explanation of construction:

1. Build a coolant container out of an old 20 lb. propane tank. Make a
removable top to refill coolant (just a 1/2" pipe plug). Weld in a drain
line connection to the bottom of the tank. Provide a way to use a regulator
and air line to pressurize the tank to 20 PSI. The drain line goes to the
mister as a pressurized coolant supply.

2. Provide an air supply regulated to 5 psi. Make a way to shut off both
this line and the coolant line when the mister is not needed. I used
solenoid valves on my CNC machine so an M code can control the mister.

3.The mister unit joins the water line and the air line with a needle valve
to control the amount of coolant delivered. Use a small block of brass to
make this assembly. The air line passes through the block and must be necked
down to 0.100 " dia. so the air velocity is high. At this point, the coolant
line intersects the air line. The coolant line must be very small, I used
0.040 " dia. at this point. Just upstream from where the coolant enters,
there must be a needle valve to regulate coolant flow rate. I just soldered
in a McMaster needle valve - 48965K24.

4. Use a 6" long 1/8" OD brass tube for the mister extension shaft. To the
end of this solder a nozzle. This must be 0.75" long and have an inside
diameter of 0.040".


Again, this unit is a total success for me. It runs up to six hours a day
with absolutely no fogging. Mist rate can be controlled from nearly nothing
to a heavy, nearly flood mist.

Pics:
http://www.metalworking.com/dropbox/...g%20Mister.JPG

Drawing of combining block:
http://www.metalworking.com/dropbox/...g%20Mister.DWG


P.S. The unit was very easy to build with the exception of the nozzle. See
"ARGH - can't drill small hole in copper" thread. G
--
An apple a day keeps the doctor away.
Two apples a day gets the doctor's OK.
Five apples a day makes you a fruit grower, like me.

Karl Townsend in beautiful Dassel, Minnesota

can somone please put a drawing back up ,, may thanks Jeff