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No Fog Coolant Mister

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John, you could shorten the extension tube to whatever length works best for you, and you could eliminate the nozzle also. Keep in mind that the extension tube is what gives you some "reach" so that the mixing block does not need to be right near the cutter.

The only thing that I need to change is the clamps for my support bars. The original clamps were made of acetal, but it is too slippery to properly hold the 5/16" rod without slipping. I am planning to make some new clamps from aluminum and see if they work any better. Right now it is difficult to get the nozzle to stay where I put it.

Eric, I have not forgotten about you, either. I still plan to make a short video and post it here, I just have not had any shop time lately.
 

j ferguson

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Thanks much Terry. this thing looks like what I need. I'll post photo when i get it done - few weeks

best regards,
john
 

j ferguson

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Hi Terry,
I found it interesting that the air passage is drilled to .125 and not the .0.90 diameter of the tube. I assumed this was to avoid any venturi effect where the .040 coolant passage lets the coolant into the flow. Pretty subtle.

Cheers.
 
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John, sorry I did not reply sooner, I've been out of town since Monday morning, just got home this evening.

I am glad you brought this up about the diameter of the air passage. When the mixing block was first designed, the .125 dimension was somewhat arbitrary, but the block was designed and made before I had any brass tubing on hand. The tubing with it's .090" ID was based entirely on what was available.

This all leads up to a problem that a few users have talked about with the unit 'sputtering' where the coolant seems to come in spurts. I wonder if a smaller diameter for the air passage would help to reduce that problem?? There is no reason that the air passage could not be .090" instead of .125" If you have not yet built yours, John, would you mind trying yours with a .090" air passage and let us know how it works? At some point this summer I plan to make another one and will try the smaller hole, but I have too many irons in the fire to make a new one right now.
 

ericg

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Hi Terry,
Like yourself I have not had much shop time and had not got the mister working, I was lying in bed recently and a brainwave struck me (very unusual occurrence!), pressure pack spray cans have small pressures and tiny orifices and work well. I thought I would make a nozzle that had an outlet as small as I could drill which was 0.8mm (1/32" or .03"). I tried that which reduced my outlet size by at least 2/3rds and 'bingo' everything is working really well now.
Just thought I would pass my experience on for what it's worth, and thanks again for the project, I will now make a second one to hold WD40 for aluminium.

regards Eric
 

j ferguson

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Hah. I made a very nice block out of 6061 - how I love to fly-cut. But guess what? first hole and so far only hole was through at .125. So too late unless I make another one.

Eric are you getting droplets and not mist with your version?

John
 

ericg

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Definitely fine droplets, no mist that I notice, and the 20psi pressure blows chips away with this smaller opening, however, I still have to properly mount it and use it on a job, just been experimenting so far.
Funny you mentioned fly cutting, that seems to be my latest stumbling block, I cannot seem to get it right, sometimes I do, sometimes not, more practice needed.

Eric
 
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Thanks for the input fellas!! I find it surprising that a smaller nozzle did the trick for you, Eric. My nozzle was originally .040" and I increased its size to .090" and it worked better at the larger size. Maybe smaller would have been better?? Guess I will have to make a new nozzle when I have the chance and give it a try.
 

j ferguson

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I haven't completed this thing yet. My air-compressor showed up today. It's a one horse California ultraquiet - no snickering. It will only be used for blowing chips and powering the no-fogger. Mine has to be a stealth shop so noise has to be minimal, and besides i'm only making little things. I'm also considering pulsing the liquid flow by solenoid valve and timer. But have to complete no-fogger first, then mess with other modifications.

And thanks Terry for thinking of this thing and Eric for your thoughts.

On flycutting, I'm using Sherline's carbide cutter set to about 2 1/2 inch circle and I don't run it very fast. I take shallow cuts until piece cleans up then feed out slowly and back even more slowly. I get a mirror finish.

I worked in a shop when I was a kid 55 years ago. We built manufacturing machinery. These projects were assembled out of aluminum plate and cold-rolled. All the connections were counter-bored socket-head cap screws. Where alignment was critical joints were keyed or pinned. Every surface including the ones you couldn't see was faced off with a fly-cutter. These things were beautiful.

All we needed to do was get one machine into a customer's plant and after that we got all the custom jobs. They loved the conspicuous precision even where it didn't matter. I loved the work. As Oskar Trumbull Scalbom, the proprietor used to say, "Just like downtown."'

So my designs may not be intelligent, but they tend to look good.


cheers,

John
 
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You will love that California Air Tools compressor. I have one of the 3/4 HP units for the basement shop and it certainly is quiet. It is more than adequate for supplying air for the No Fog Mister and for lightly blowing the chips out of an occasional blind hole. Nobody even hears it run, but my 6 HP unit out in the garage makes its presence known to us and the neighbors every time it fires up.
 

j ferguson

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Hopefully the rest of the ingredients will show up today. Following Eric's lead, I'm going to make a nozzle. 'Ought to be a bit of a challenge without a lathe, but I'll forgo the tapered nose. Terry, you were right about drilling the .040 hole. It took two tries, fortunately, the bit that broke hadn't penetrated into the .125 passage. I had planned to use two regulators, one for the air and one for the fluid, but decided that with the needle valves on each line there were too many variables and the thing would be hard to control.

Having a single regulator does provoke a question, though. The height of the fluid container relative to the mixing block will affect flow if the air pressure to the fluid container and the block is the same. Has either of you messed with this?
 
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I have not experimented with it, but have always kept my reservoir below the height of the nozzle. When I shut off the air, the flow of fluid ceases as well and it does not continue to siphon out through the nozzle as it would if the reservoir were higher.
 

j ferguson

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Thanks for the note, Terry. My mixer is finished, photo to follow. Being latheless, threading the brass tube was a bit of a challenge, but I finally hit on chucking it in the drill press and putting a die in holder on the table. I was able to turn the chuck by hand to get about 3/8 inch of thread which seemed enough. Filter holder was ordered from filtersfast which despite their name is none too swift, I'm still waiting.
 
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Hmmm. When I ordered from them I got everything rather quickly. Sorry to hear you are experiencing a delay.

Keep in mind that when I listed Filtersfast.com on the bill of materials I chose them only because they had everything I needed and the prices were reasonable. Other builders can choose another supplier if they wish, but I had good luck with the vendors listed on the BOM.
 

j ferguson

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Hi Guys,
This is what my effort produced:

fogless1.jpg

The filter holder showed up on Saturday. Terry you chose well, the thing is really substantial. I'm going to try it with the.090 throat first and then if that doesn't work, I bought the 1/4 inch hex brass to make a nozzle with.

And again, thanks to you all for a useful design.

john
 

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When I get my mill mounted to its new table ,I'll have to make this mister too. Love the fact it dosent use gallons of fluid to work. Thanks for the plans .
 

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At long last, I cleared my backlog of the less fun things, and got started on my SlimVise project. First act was to make two smaller pieces out of a big one. This was more of an experiment to see how the no-fogger worked than the best way to do this.

fogless2.jpg

It worked just fine, and without a nozzle. i ran 20 psi on the system. The adjustment of the coolant valve is really twitchy though, possibly because this HomeDepot valve is not intended to meter. So next "improvement" is to find a real metering valve. The thing that's nice about this is that you can feel the air stream cool when the coolant starts to feed and also you can see very small droplets accumulate if you aim it at a piece of paper.

I'm glad i made this thing.
 
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Mine is touchy about its adjustment also, so it might not be your valve. I am considering making my own needle valve so that I can better regulate the coolant flow, but there are too many other projects going right now. Another method that I have considered is to use two regulators. One set at about 20 PSI for the air flow through the mixer, and the other set at 30 or 40 PSI to provide pressure for the fluid. I believe that the surface tension of the fluid is high enough that at 20 PSI there is not enough pressure to keep the fluid moving past the needle valve when it is barely even open. More pressure behind the fluid might help, but I don't know for sure.
 

j ferguson

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Hi Terry,
I bought two regulators with the thought that the fluid and air feeds might work better with different pressures although I was thinking of less pressure on the fluid, maybe depending more on venturi effect to pick it up. The valves I have are not really needle valves like you used to use for air-correction in carburetors so it's more of an off-and-more-or-less-on choice, not a a gently ramping increase in flow. You may be right that the stickiness of the coolant could clog a real metering valve. I guess I'll have to see if i can find one, and then maybe also mess with the air-pressure too.

I have some old propane valves around which have long needles, maybe one of them can be modified to do this job better.
 

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Mine is touchy about its adjustment also, so it might not be your valve. I am considering making my own needle valve so that I can better regulate the coolant flow, but there are too many other projects going right now. Another method that I have considered is to use two regulators. One set at about 20 PSI for the air flow through the mixer, and the other set at 30 or 40 PSI to provide pressure for the fluid. I believe that the surface tension of the fluid is high enough that at 20 PSI there is not enough pressure to keep the fluid moving past the needle valve when it is barely even open. More pressure behind the fluid might help, but I don't know for sure.
Hi Terry,
I bought two regulators with the thought that the fluid and air feeds might work better with different pressures although I was thinking of less pressure on the fluid, maybe depending more on venturi effect to pick it up. The valves I have are not really needle valves like you used to use for air-correction in carburetors so it's more of an off-and-more-or-less-on choice, not a a gently ramping increase in flow. You may be right that the stickiness of the coolant could clog a real metering valve. I guess I'll have to see if i can find one, and then maybe also mess with the air-pressure too.

I have some old propane valves around which have long needles, maybe one of them can be modified to do this job better.
I run mine at a 15 PSI differential, 45 on the air and 60 on the fluid. That way I'm assured of having fluid flow at all delivery rates. I'm using pneumatic flow controls for the fine adjustment, about 16 inches back from the outlet for both fluid and air at the mixing tee.
 

j ferguson

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After another session with my no-fog coolant device, i have it adjusted exactly right. It turns out that it just needed more fussing than I had expected, but it now works beautifully, and amazingly doesn't make much of a mess. the longer handles on the valves make them pretty easy to fine-adjust.
 
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Good to hear that you have yours working well. I agree, the valves do require a bit of fussing to get them just right. I keep having trouble with the coolant valve slowly closing itself after I get it set. I attribute that to the rubber o-ring inside the valve. The o-ring always seems to pull the valve back a bit. I have been thinking about making some new seals out of UHMW and see if that resolves the setting problem.
 

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I was finally able to muster enough smarts to devise a 3 hour CNC run - aluminum. The difference between none and a bit too much is REALLY twitchy on my coolant valve. Because I have the little handle and fiber-gland under the cap, I can set it so it's ok, but it is a struggle - I must have just lucked out on earlier short runs. So I'm going shopping for a finer coolant valve. I think they call them metering valves. But no mater what I do, there is NO FOG.
 

j ferguson

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I finally caved in and bought a proper metering valve, a Parker 1715-003381100. I think I paid $24 for it on Amazon.

It has a wonderful micrometer adjuster which makes getting the right amount of coolant in the mix EASY.

parker1.jpg

This is how the whole thing looks:

fogless3.jpg

can never have enough detail:

metering-valve1.jpg

As you can see, this thing has gotten pretty bulky. the next move may be to mount the valves on another block of aluminum and just run the tubing into simple fittings on the mister itself.

In any case, the twitchiness on getting just the right amount of coolant in the airstream is gone.

parker1.jpg

fogless3.jpg

metering-valve1.jpg
 
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Ooooo sweeeeet!! Would you mind sharing your source and a ballpark price on that valve?
 

JPigg55

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Just what I've been looking for, thanks Terry.
I know you stated the nozzle isn't necessary, but got me wondering if using Mig welder tips might work and be an easy addition.
Thinking of experimenting with a flexible metal line as well.
 
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Thanks Michael!! I think they would be well worth looking into. I found that the little rubber o-ring in the valves that I used is what is causing the problem there. When you stop turning the screw, the rubber pulls it back slightly, making it difficult to get it set correctly.

JPigg55, it certainly will not hurt to experiment a little. That's how these sorts of projects get better! I've still got the original nozzle on mine and it works just fine. As for the flex nozzle, I think it will give you trouble. Another member tried that some time back and the moving air was unable to carry the droplets inside that 'rough' tube. Straight, laminar flow seems to be an important part of making it work properly. With the flex line the coolant dropped out of the air and built up inside the nozzle until the air could manage to 'grab' it again and spit it out in spurts. Not trying to discourage you, but just letting you know what we saw happen before.
 

JPigg55

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As for the flex nozzle, I think it will give you trouble. Another member tried that some time back and the moving air was unable to carry the droplets inside that 'rough' tube. Straight, laminar flow seems to be an important part of making it work properly.
Yeah, I read that and saw the picture. Was thinking more of a flexible line like the old oil cans used, metal, spiral wound type. Might work, might not, never know until you try I guess.
 
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Ah, yes. It may certainly be worth a try! Another material I thought of that may work would be the type of plastic that are used for the suction tubes at the dentist office. They are hard plastic, smooth on the inside, but can be bent and they retain their shape.
 
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