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Attached is a zip file containing seven drawings in PDF format. These drawings are the plans for a no fog coolant system that I am building.

Compressed air is required, but the design will apply coolant to your cutting tools without creating a foggy mist in the air when it is used properly. In practice, the air volume is turned up just enough to gently blow chips away from the cutting area, which will also carry small droplets of coolant to the tool.

Most dimensions can be changed without issue, however there are two dimensions that are critical: the .040" hole in the mixing block, and the .040" hole in the nozzle. The air passage through the mixing block must be large enough to slow the speed of the air flowing through it, but must be small enough for the air to travel fast enough to carry the droplets of coolant along.

I made my mixing block from brass for three reasons, but aluminum could be used: 1. I like the look of brass 2. It was what I had 3. Allows assembly by soldering if desired

The drawings show using only one regulator on the system, but two can be used, providing different pressure settings for the mixer air and for the fluid reservoir.

This coolant system could be used with any light coolant, such as Kool Mist, WD-40, or even soluble oil. Heavy cutting oils will most likely not work well with this system.

The drawings and bill of materials depict the system as I am currently building mine. If it becomes necessary to make changes to a drawing, I will do so and post the revised drawing here, replacing the original, then will post a note to the thread. As always, some individuals will do some things differently, and that is okay.

Comments and ideas are welcome, let me know what you think.

Thanks for sharing. This should come in very handy.


Thanks for going to the trouble of posting the drawings of your project, I can definitely see one in my future. What is different about your design and a mist coolant nozzle? Why no fog?

(01-05-2014, 06:13 PM)TomG Wrote: [ -> ]Terry,

Thanks for going to the trouble of posting the drawings of your project, I can definitely see one in my future. What is different about your design and a mist coolant nozzle? Why no fog?


First, you are most welcome!

Most misting type coolant systems use a compressed air jet through a venturi to create a vacuum at the end of the coolant line. Atmospheric pressure then pushes the coolant into the venturi so that the air stream can carry the coolant to the desired target. This type of system requires very high air velocity, creating high shear forces which tend to atomize the coolant, then carry it onward as a very fine mist. Much of this mist floats about in the air, creating a fog that can be very irritating, not to mention that it leaves an oily film on everything in the area. The high speed air jet also tends to be quite noisy.

This system does a few things differently. First, the coolant reservoir is pressurized to about 5 or 10 PSI. Pressurized coolant then enters the mixing area without the need for a high velocity air stream or a venturi. Instead, the air passage is larger, allowing the air to travel at a lower velocity as it picks up the coolant droplets. They are then carried down the extension tube and out through the .040" nozzle orifice, which increases the velocity of the air and coolant just enough to get them to the target, but without creating the type of shear that atomizes the droplets. Using just enough air to clear the chips from the cutting area combined with just enough coolant to make things damp is all that is required. Due to the reduced volume of air exiting the nozzle, this system is also significantly quieter than the common venturi system.

This design is similar to a commercially available system for which the designer holds a patent. It appears that there is a significance to the size of the hole through which the coolant enters as well as the size of the hole through the nozzle, and the patent holder went through the trouble of experimenting to find out what size hole worked the best.

Now I should mention that if a person were to sell these drawings, or build and sell these systems, he would be guilty of patent infringement, but that is not the case if an individual builds one strictly for his own use.

I have not tested this for myself yet as I am still building mine, but it appears that there may be an advantage to using two separate air pressure regulators; one for the reservoir pressure, and one for the air jet. Terry S built a similar system, but his uses only one needle valve with two regulators. My thought is that this system with two needle valves may negate the need for two regulators, but I will not know that for sure until I complete mine and do some testing with it.
For those that would like the PDF plans as one PDF file, I've attached it here.
Thanks for making the plans available Terry.


For those of you that work in that OTHER measuring format Big Grin I have created a metric version of drawing 6 of the set of drawings and have it here for your convenience. Sadly, not everything converts over quite right, but this drawing should make life a little easier for you just the same.
Thanks Terry, this is exactly what I need for my X2 CNC conversion. I plan to cut primarily aluminium and was looking for a good way to include a wd40 coolant system. Very much appreciated, I've downloaded the plans and will definately be building one in the future.

Thanks for sharing this with us. I was looking at some form of cooling system for my Warco WM 16 mill for the future so this will be on my toduit list.

I finished my no fog coolant sprayer some time back, and have experimented with it quite a bit. I found that the nozzle could be done away with altogether, or the hole size should be increased to about 0.090".  It seems to work much better this way. In my case, I made the hole in the nozzle larger. The weight of the nozzle helps to counterbalance the weight of the mixing block, and it stays in position very well.

I run a single regulator set at 10 to 20 PSI, and with the two needle valves, it can be used with just air, just coolant, or with both. Optimum settings seem to be with enough air flow to gently push the chips away from the cutter and just enough coolant to barely make things damp. You can mill for hours and the coolant level only drops an inch or so in that time. The coolant needle valve is very sensitive, so have a little patience when getting it set.

Could you post pictures of it set up on your mill?

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