No Fog Coolant Mister

Tom,

I would first try enlarging the hole in your nozzle, it's size is not so critical as the .040" hole in the mixing block. You might even try removing the nozzle. Once you've done that, you can use more air flow to carry the small droplets to the work.

What is happening right now is that the air starts to carry the droplets at the mixing block as it is travelling at a velocity high enough to do so. Once the air/coolant stream hits the large inner diameter of your flex hose, the velocity is greatly reduced and the fluid droplets drop out of the slower moving air. Once the liquid forms a large enough 'puddle' in the flex hose, the air pushes all of it out at once. You also might be opening your fluid needle valve too far due to the perception that there is no coolant coming through.

The original design called for a straight nozzle that is relatively short in length, and small enough in diameter to keep the air velocity high enough to still carry the droplets, but not so high that the droplets become atomized, thus not creating a fog in the room. The flex hose you are using may be what is causing the problem.

I made a prototype that worked reasonably well, but it was a bit bulky. The mixing block was too large, as were the needle valves that I used in the first design. The design in the drawings is a smaller version of that prototype, and I still need to build one of the smaller ones. The needle valves are sensitive, especially if they are overly large, but the sensitivity is not as bad at lower pressures. You should only need about 20 PSI at max, maybe a hair bit more, but probably less in most cases. You are looking for air volume, not pressure. A higher volume stream, at lower pressures, can carry tiny droplets of fluid in the air stream. Air will provide most of the cooling, aided by the cooling effect of a tiny bit of fluid.

In use, you should turn on the air first. Get a nice flow going at a lower pressure, but not so much flow that it gets real noisy. Next, just crack the fluid valve open a tiny bit while holding a finger out ahead of the nozzle. When the fluid starts coming, you may not see it, but you will feel it as the temperature of the air stream will drop sharply. If you watch closely you will see that your finger is starting to get wet, but not dripping wet. That is all you need. One canister of coolant should last for several hours, as in all day or more. Granted, a heavier milling job will need a bit more coolant, but you will be surprised at just how little it really takes.

Fiddle with your modifications a bit, then come back and let us know how you've done. Feel free to tell us what works and what doesn't, and don't be afraid to critique my design if you find a flaw with it, even if it is only a personal preference. I am going to be out of town for a couple of weeks, but will check back here when I return.

Wermie,

Thanks for your explanation and suggestions. I've got a kitchen remodel in progress so may not be able to get back to the coolant system for a few days. But I will post what I did and the end results. Enjoy your two weeks away, I'm assuming it's vacation.

Tom S
 
The original design called for a straight nozzle that is relatively short in length, and small enough in diameter to keep the air velocity high enough to still carry the droplets, but not so high that the droplets become atomized, thus not creating a fog in the room. The flex hose you are using may be what is causing the problem.
Just adding a plus 1 to this. The length will be a problem too, but the bends and restriction are certain to turn it back into an atomizer.
 
Wermie,

Thanks for your explanation and suggestions. I've got a kitchen remodel in progress so may not be able to get back to the coolant system for a few days. But I will post what I did and the end results. Enjoy your two weeks away, I'm assuming it's vacation.

Tom S

Broke away from the kitchen remodel yesterday and played with the no fog mister. I opened up the brass plug in the end of the nozzle from .040" to .125" and re-plumbed the system with one regulator. With the air pressure set to 20 psi it works much better. You are correct that the coolant feed needle valve is ultra sensitive. Maybe the local PetSmart or Petco stores will have an aquarium valve smaller than the 1/8" NPT valve I'm using. Still need to play around with the inlet air pressure and possibly replace the flexible nozzle with a small diameter rigid tube. The volume of coolant used is also greatly reduced. Did about five hours of milling and the level is down about 1" - 1-1/2".

All this being said this is a great system. Got some heavy milling to do (building a sheetmetal brake for my hydraulic press) so we'll see how it works under those conditions. Nuf said, heading to the shop.

Tom S.
 
Wermie,

When I was a young fellow and working in a toolroom, the boss hired an additional man. He had some gaps in his education and did not understand using proper feeds and speeds on a Bridgeport.
He ordered a "Cool Tool" mister to help reduce his consumption of end mills. When in use, the small vial on the mister emptyed quickly. One day Jerry had a "Brainstorm" and removed the vial and plugged on a syphon hose, hung the One Gallon can of "Cool Tool" with heavy wire to the collet rack and went to work! He had a one inch endmill working on a block of A-2 Tool Steel. Very soon my Van Norman mill and I were engulfed in a "Blue Cloud" even though it was 10 feet away from the main event! The tool room was about 20 by 30 feet in size. I soon walked out of the room.

The plant superintendent came along five minutes later and ask what I was doing?... I replied waiting for the air to clear! ......

The "Blue Cloud" now had emerged into (3) adjacent areas. As the Super. looked around the cloud was approx. 10 feet into the area I was standing in.
His face turned BRIGHT RED and he stalked into the "Blue Cloud", dissapearing totally from site. His yelling could be heard over the racket of a press room.

That was the end of the spray mist!

I have not used one in my home shop, remembering the stench and mess, but will try yours. Have you tested any of the water mix coolants?

Reguards,
Restorer
 
I used some Kool Mist and some Syn-Kool in my prototype and both worked quite well. A few ounces will last for quite a long time if the unit is set properly. No problems with odor or mist. Air does most of the cooling, with the aid of just a bit of moisture from the coolant itself.

I still have to build my final design and do a build article on it, but time in the shop has been really tough to come by as of late.
 
I look at this project and I like it. However I have maybe a silly question. When you mix the water and oil is there any concern that the water will completely separate from the oil and cause rust and corrosion on my mill table and/or vice? I dont typically wipe down things immediately after a quitting for the day. But maybe I need to start. I have a heated garage so I don't have worries or rust otherwise. Just a question I have. Thanks!


I used some Kool Mist and some Syn-Kool in my prototype and both worked quite well. A few ounces will last for quite a long time if the unit is set properly. No problems with odor or mist. Air does most of the cooling, with the aid of just a bit of moisture from the coolant itself.

I still have to build my final design and do a build article on it, but time in the shop has been really tough to come by as of late.
 
No such thing as a silly question!! Glad you asked! The coolant is not very oily, but does have some lubricating qualities. Kool Mist and Syn-Kool both come as a concentrate, and you mix them with water at an amazingly light mixture. I have not had them separate at all, even when unused for several weeks. I have not seen it separate if left in a small puddle either.

I always try to give my machines a quick wipe down when I am done with them, its just a good habit to get into I think. I used to leave things sit and then go on a cleaning binge once in a while. Getting in the habit of cleaning up as soon as I am done helps me to keep my shop area much cleaner. It is nice walking into a clean shop to start on a project, rather than walking in and having to clean up a mess first!
 
On the first run with my (soon to be converted) ltl Mister, I had the flow set too high. I was using Boelube concentrate which if it's left to
sit seems to attract rust or corrosion.
I was making shackles for the Jeep springs and it was around 2am when I knocked off. I had quite a mess on the mill so being lazy I grab
some fine sawdust I keep in a box and sprinkled it on the mess and hoped the shop gremlins would clean up overnight.
The next morning they hadn't so over coffee I cleaned it up. The surprising thing was that with the sawdust mixed with the chips and coolant,
the shopvac seemed to pick it all up easier. I then wiped it down and tossed on a coat of lube.
Another interesting thing about boelube is that when it does sit it will break down the 'grime' in the t-slots and such. Almost like a caustic degreaser.

_Dan
 
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