12-31-2013, 01:12 PM
Here's a brief summary with pics of a fogless mister I have been designing and building.
I built this for use on my BP mill. I don't do enough heavy work to justify the maintenance of a flood system - and my old-timer "Mystic Mister" tends to fog up my basement shop in no time. At the recommendation of another member, Terrywerm, I looked into the design/build of a fogless design. The system I built uses a 20 oz Coke bottle for a fluid reservoir, and has two regulators: one for air against the nozzle and one for air pressure on top of the fluid reservoir. I have about 10 hours on the system now, and am quite satisfied once I have learned how to "tune" it. It makes no fog whatsoever.
The mixer assembly is made from a single piece of soft brass square stock.
The air enters the lower tap and passes straight through into the mixing tube. The fluid enters the upper tap and is regulated via the needle valve. The fluid and the air mix in a "low velocity" chamber under the needle valve to prevent further "atomization" of the fluid. The needle valve seat orifice is .040 in. I find that in normal use, the needle valve is about 1/4 turn open with 10 psi air pressure in the reservoir.
Here's a view of the disassembled mixer valve showing the needle stem, the packing gland and the captive O ring.
Here's a detail showing the packing gland with the captive O ring slot. The O ring is an 1/4 x 1/8 standard size. It is slightly compressed on the OD in the gland. The gland compresses the O ring in the "Z" direction until the gland bottoms out. This squeezes the O ring against the needle stem making a water tight sea. Cutting fluid is not exposed to the needle threads or the packing gland threads.
Here's a view of the "Control Panel." I have it mounted on the right hand side of the mill for east of adjustment when running. The right column is for air and the left column is for fluid. The "toggle" valves on the top of each column start and stop the flow with a flick of a finger.
Here's a view of the back of the control panel. The Coke bottle, regulators, etc. are mostly shielded from flying chips by the panel.
Here's a view of the mixer installed on the mill. I like to position the mixer so that the needle valve knob is easy to reach during operation.
Some notes:
1) I need to do some more work on the Tinker Toy mount for the mixer head. Right now I have to use an Allen wrench to adjust it. I may look at retrofitting one of those multi-flex dial indicator holders. I find that fine tuning the position of the air blast can make quite a difference on the efficiency of chip clearing. When taking a heavy side cut, the mill runs noticeably quieter when the chips are being cleared and re-cutting greatly reduced.
2) There is absolutely no fog generated, but I find that I often have to "restart" the fluid flow by opening and then re-adjusting the needle valve after I have stopped the fluid flow. Plus, I like to start the cut with a little extra splash of fluid on the cutter before settling down the the mist feed. I may look at adding a by-pass valve to the needle valve to get this function. I find that the proper flow of fluid generates a sound like "bacon frying" when operating (you have to listen carefully to hear it). If I cannot hear the bacon sound, I tweak the valve open and then closed to get the fluid flowing.
3) The final mixing nozzle at the end of the mixing tube has a .040" bore (#60 is smallest drill bit that I own). When you do the math, this bore regulates the air flow at about 0.3 scfm with 5 psi of air against the nozzle. The air flow is audible, but not loud. The nozzle velocity at this setting does a good job of clearing chips from the cutter as long as the nozzle is within about 3/4 inch of the cutter.
4) After about 4 hours of cutting steel on a project, I still haven't used up 20 oz of fluid. I have been using the standard dilution of "Cool Mist."
Terry S
I built this for use on my BP mill. I don't do enough heavy work to justify the maintenance of a flood system - and my old-timer "Mystic Mister" tends to fog up my basement shop in no time. At the recommendation of another member, Terrywerm, I looked into the design/build of a fogless design. The system I built uses a 20 oz Coke bottle for a fluid reservoir, and has two regulators: one for air against the nozzle and one for air pressure on top of the fluid reservoir. I have about 10 hours on the system now, and am quite satisfied once I have learned how to "tune" it. It makes no fog whatsoever.
The mixer assembly is made from a single piece of soft brass square stock.
The air enters the lower tap and passes straight through into the mixing tube. The fluid enters the upper tap and is regulated via the needle valve. The fluid and the air mix in a "low velocity" chamber under the needle valve to prevent further "atomization" of the fluid. The needle valve seat orifice is .040 in. I find that in normal use, the needle valve is about 1/4 turn open with 10 psi air pressure in the reservoir.
Here's a view of the disassembled mixer valve showing the needle stem, the packing gland and the captive O ring.
Here's a detail showing the packing gland with the captive O ring slot. The O ring is an 1/4 x 1/8 standard size. It is slightly compressed on the OD in the gland. The gland compresses the O ring in the "Z" direction until the gland bottoms out. This squeezes the O ring against the needle stem making a water tight sea. Cutting fluid is not exposed to the needle threads or the packing gland threads.
Here's a view of the "Control Panel." I have it mounted on the right hand side of the mill for east of adjustment when running. The right column is for air and the left column is for fluid. The "toggle" valves on the top of each column start and stop the flow with a flick of a finger.
Here's a view of the back of the control panel. The Coke bottle, regulators, etc. are mostly shielded from flying chips by the panel.
Here's a view of the mixer installed on the mill. I like to position the mixer so that the needle valve knob is easy to reach during operation.
Some notes:
1) I need to do some more work on the Tinker Toy mount for the mixer head. Right now I have to use an Allen wrench to adjust it. I may look at retrofitting one of those multi-flex dial indicator holders. I find that fine tuning the position of the air blast can make quite a difference on the efficiency of chip clearing. When taking a heavy side cut, the mill runs noticeably quieter when the chips are being cleared and re-cutting greatly reduced.
2) There is absolutely no fog generated, but I find that I often have to "restart" the fluid flow by opening and then re-adjusting the needle valve after I have stopped the fluid flow. Plus, I like to start the cut with a little extra splash of fluid on the cutter before settling down the the mist feed. I may look at adding a by-pass valve to the needle valve to get this function. I find that the proper flow of fluid generates a sound like "bacon frying" when operating (you have to listen carefully to hear it). If I cannot hear the bacon sound, I tweak the valve open and then closed to get the fluid flowing.
3) The final mixing nozzle at the end of the mixing tube has a .040" bore (#60 is smallest drill bit that I own). When you do the math, this bore regulates the air flow at about 0.3 scfm with 5 psi of air against the nozzle. The air flow is audible, but not loud. The nozzle velocity at this setting does a good job of clearing chips from the cutter as long as the nozzle is within about 3/4 inch of the cutter.
4) After about 4 hours of cutting steel on a project, I still haven't used up 20 oz of fluid. I have been using the standard dilution of "Cool Mist."
Terry S