Building a mist coolant system for my mill

sortafast

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So I have started building a mist coolant system for my mill. My mill has flood coolant, but it doesn't work and I don't want the mess so I am DIY'ing an MQL type mist/droplet coolant system. After testing it with water it looks like it should be no sweat to get it 99% fog free. Got most everything bought (should come in well under $100) except for some solenoid valves and such but I am trying to figure out what kind of coolant to run. Right now I am just using a spray bottle and WD40 but I want to switch to something more better. Since this is in a small shop with not very good ventilation, I want to get something that will not have adverse effect or F-up my lungs too badly. So far I want to try just strait up mineral oil, but I can also get the Koolmist 77 locally which seems like the standard issue coolant for these types of set ups. Anyone have any thoughts? I will probably do a write up on it once I get a few more things made and bought and after I figure out a few things with the mill.
 

wquiles

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The standard Koolmist is what I started using when I first started experimenting with coolants/etc., and it works well, IF and only IF you use it with distilled water, and go heavily towards the heavy concentration range (don't go light). I initially had a little bit of rush, and after talking to them over the phone, the technical resourced recommended both distilled water and a heavier concentration - the rust stopped :)
 

sortafast

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Nothing else removes heat like flood, especially with titanium.

For MQL the defacto standard is AccuLube LB2000.
Problem with the Flood coolant is that it doesn't work, I am too cheap to fix it, and frankly I don't want coolant all over the shop. The mill has pretty much no enclosure to it so it would be a mess. Having a hard time keeping chips contained as it is. I have been using some shot up IPSC targets and they help, but going to fab up a partial enclosure some time soon.

On the plus side I am just waiting on a bracket to get made to hold the coolant container and a couple solenoid valves, then I just need to plumb everything in, and I should be good to go. Will probably have to upgrade the compressor at some point as well, but for now it works.
 

precisionworks

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... and frankly I don't want coolant all over the shop ...

When a mister is set for a flow that's high enough to cool the part or tool there's overspray/dripping/coolant pools around the mill. As soon as the mist hits the rotating tool the tool acts as a flinger & effectively distributes coolant everywhere close to the tool (close meaning about a three foot radius). This doesn't happen when the tool is chugging along at 100 rpm but the higher the spindle speed & the larger the tool diameter the worse it is. In addition the mist that does stay on the tool flows down to the table & is carried back to the tank by a drain tube. Mist & flood both obscure the view of the cut line/tool path & some jobs require turning the mist off in order to see where the tool is going, especially if milling to a scribed line. An added benefit is that a very fine mist setting covers safety glasses in record time ...

Will probably have to upgrade the compressor at some point as well, but for now it works.
You may want to consider moving the compressor as far away from the mill as possible unless you enjoy compressor noise - don't laugh, a well maintained compressor is a joy to my ears (when wearing both Hearos plugs & David Clark earpro). It may be a bit distracting with unprotected ears.
 

sortafast

Enlightened
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Oregon
When a mister is set for a flow that's high enough to cool the part or tool there's overspray/dripping/coolant pools around the mill. As soon as the mist hits the rotating tool the tool acts as a flinger & effectively distributes coolant everywhere close to the tool (close meaning about a three foot radius). This doesn't happen when the tool is chugging along at 100 rpm but the higher the spindle speed & the larger the tool diameter the worse it is. In addition the mist that does stay on the tool flows down to the table & is carried back to the tank by a drain tube. Mist & flood both obscure the view of the cut line/tool path & some jobs require turning the mist off in order to see where the tool is going, especially if milling to a scribed line. An added benefit is that a very fine mist setting covers safety glasses in record time ...

You may want to consider moving the compressor as far away from the mill as possible unless you enjoy compressor noise - don't laugh, a well maintained compressor is a joy to my ears (when wearing both Hearos plugs & David Clark earpro). It may be a bit distracting with unprotected ears.
The mill is a CNC so I really don't have to worry about seeing where its cutting too much. I built some small moveable shields but I am trying to figure out what I want to do for a more solid, permanent solution. I think the system I am building will be easier to contain than a flood coolant system. I already wear hearing pro when running the mill. Between the RPC, mill, and small compressor it gets a bit annoying so I wear the muffs to keep the sanity. Adding a larger compressor shouldn't be terrible. I am thinking of making a vented and baffled enclosure for whatever I get, but I will cross that bridge when I get there.
 

sortafast

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Well, the system works. Just need that bigger compressor so I cam actually run it hard. The little compressor I have is struggling a bit to keep up, but it works ok for now. I am thinking I want to add a 2nd sprayer to run on the other side so that I get full/better coverage. Other than spending a bunch on fittings, I think I am in under a hundred for the whole mess. I need to find some better pressure regulators that work at the lower pressure for the coolant tank. Its not even registering on the gauge. But so far it has run very well. Not sure if there has been a ton of improvement to the surface finish but it seems somewhat better in cutting performance, if that makes sense.
 
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