Cold/chill gun?

(Julien Heyman) #1

Does anyone have experience with a “cold gun” that take compressed air and makes a jet of cold air ? e.g. this ?

I wonder if it could work well in situations where air+mist coolant is usually necessary, to not have to use any coolant. It looks like a pricey item anyway, so probably irrelevant for hobby CNC, just wondering.

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(William Adams (Carbide 3D)) #2

I found one ages ago, and asked after it on I think the Shapeoko forums — Catalin Voinescu did some calculations and determined that just a compressor works fine for the spindles which can be mounted on a desktop machine.

There was this article though: http://espace.library.curtin.edu.au/R?func=dbin-jump-full&local_base=gen01-era02&object_id=18869

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(Neil Ferreri) #3

No, but if you turn a can of air (the kind used for dusting electronics) upside down, you’ll get plenty of cold blasts for a small job.

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(Pete) #4

I have used one. They use a lot of air so you would also need an industrial compressor to keep up with it. like you said, probably not worth it for a hobby setup.

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#5

Air hungry, but effective. As @Winters636 said, not really worth it for hobby work. Aside from the high volume needed, you need a way to get rid of the heat from the hot end, and the air supply needs to be clean and dry to prevent freezing and fouling.

They tend to be used when you need moderate cold air volume (cold, like 0C or lower cold) and refrigeration gear isn’t practical. There are a LOT of places this applies in industry, but the cost of operation is high. They have other uses, and I have used, a few times, handheld heat guns that are essentially Hilsch tubes, and been on a few jobs where the tubes are used as the cold-air source for a cool suit.

They are very, very neat devices, but niche.

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(mikep) #6

They’re vortex tubes. Yes, they work to generate a cool stream of air. They use a TON of air though, and are very, very loud. You can make your own (with a little work) and some really simple parts to try though.

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(James H. Miller) #7

This is the exact video I was thinking of when I saw this post. :slight_smile:

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(Paul Alfaro) #8

echo lots of air comments, not ideal for most individuals

i am intrigued by the mist options with liquids that evaporate. so minimal mess and air.

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(James H. Miller) #9

Another option is to mist denatured alcohol. We had a tool and die maker at my day job that either used denatured alcohol in a spray bottle or vegetable oil when he was on a Bridgeport. When he used the vegetable oil it smelled like he was cooking french fries. :grinning: He was a very good tool maker also, he left my plant to go manage a tool room with 50+ guys under him.

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(Luc) #10

I wonder how this would affect the air quality with very fine denatured alcohol or some other solvent flying through the air at high speed.

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(Vince) #11

I run all kinds of alcohol mixes. Usually a 50/50 mix with water that’s not flammable and safe to use/store.

You shouldn’t be spraying enough to even notice is in the air. It takes a surprisingly small amount. Datron is well known for using an alcohol MQL system and it lubricates as well as cools.

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(Paul Alfaro) #12

it’s very minimal, but it’s worth looking into.

I have an enclosure and have concern about combustion possibilities.
confined space + alcohol potential + endmill decides to kiss the alloy workholding :scream:

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(Vince) #13

Datrons are fully enclosed and run close to 100% alcohol I believe.

50/50 should be pretty safe but maybe add a small exhaust fan for an enclosed setup. On water/meth injection cars I usually reccomend a half and half mix also due to safety.

This is a secondary mister nozzle cranked to max. Perfectly safe

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(Paul Alfaro) #14

that’s awesome @Vince.Fab dig the vid

i’m not that familiar but i believe there’s only a small range where the air to fuel would combust. much like the perfect storm required for wood chips. since my machine is housed in an enclosure that resides in a small closet i don’t want to accidentally flood my apartment lol.

until i look into it more compressed air only will have to suffice

i read this on the neo setup guide;

The following must be observed when the machine is operated with cooling lubricant:
During continuous machine operation the area around the machine must be well ventilated or an exhaust system for the removing the cooling lubricant vapour must be installed. When installing the room exhaust system, note whether the cooling lubricant in use is lighter or heavier than air. Install the room exhaust system at the top or bottom as applicable. The AGW values (maximum workplace concentration values) of the cooling lubricant must be below the maximum limit.
In HVAC technology, the following general empirical values are used for the air exchange numbers (i.e. exchanged air per hour):

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(William Adams (Carbide 3D)) #15

Hal Clement had a really cool story on this in his collection Space Lash (which was originally publishes Small Changes — one of the few books we had in our house when I was young I read it quite a few times.

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(RaXor) #16

I’d like to make a note regarding using mist in general.

I’d strongly recommend avoiding any kind of Mist Cooling if you don’t have an enclosed area with filter filtering the air, whether it is Mineral Oil or Alcohol.

Alcohol can and will cause very strong damage to the brain, especially when it is in the air, and I’m guessing the alcohol you use isn’t the one you drink, so it is a much stronger one.

Now take a deeper look at it, if you can read “meth” anywhere in the name of the alcohol, then you can guess it’s one of the worst you could potentially use.

Regarding Datron using 100% alcohol I’m pretty sure they got a proper extraction system integrated in it. I would be surprised if not.

I often see the guys inside videos with a cloud of mist or milling stuff all day long with no or very little ventilations, seriously this is a very dangerous thing to do.

Sure it is bothersome but at the end it’s worth it.

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(Jonathan Anderson) #17

I would just like to add some sources to this and temper it a little bit.

Aerosolizing different lubricants is not as hazardous as you make it sound.

Mineral oil has no known health hazards at quantities we are discussing. Note the zero on the blue segment of the NFPA diamond in the SDS.

There is no reference for “stronger alcohols” so I’m not sure what that means. Chemicals have no inherent strength without a reference point.

Aeroslizing ethanol has no health affects at these levels either. In fact, it’s used to treat pulmonary edemas due to it loosening lung sputum.

Aerosolizing IPA (isopropyl alcohol) does not seem to pose issues either at the levels we are talking. The book, “Occupational, Industrial, and Environmental Toxicology” mentions that high levels of IPA in poorly ventilated areas, like in printing or lithographic industrial environments, can cause ocular or pulmonary irritation (your eyes may water and you might cough) and potential nervous system depression. Certainly not anything chronic or life-threatening and that’s only in industrial areas with poor ventilation.

As for methanol, yes, it’s toxic, don’t use it as a primary coolant. Using denatured alcohol (ethanol + other alcohol (methanol and IPA are common)) may pose a slight risk if used continuously, in high concentrations, in poorly ventilated environments.

Really, with what we do, read the SDS, open a window, and don’t spray hideous amount of coolant into the air. I use a 75/25 IPA/H2O mixture misted onto aluminum when I mill it and it works just fine. Most of the vapor condenses onto the part and very little aerosolizes to a point where I can inhale it.

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(Vince) #18

One for you
One for me

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(RaXor) #19

I understand your mindset is much more scientist based on facts and studies.

Mine is much more common senses.

Stronger alcohol just means the mix of alcohol.

Regarding Mineral Oil, it is well shared fact that it does accumulate into your lungs till it does something bad.

I remind having read a story on a CNC forum about a guy suddenly having trouble breathing from day to tomorrow, he wasn’t old at all, like in his early forties as I remind.

He went for some medical checks and the results were pretty clear, he has oil based product stuck inside his lungs, like a small pocket of oil, went onto a surgery to remove it asap as the doctor said he had a few months left to live if he don’t remove it, after that he said he moved to flood cooling and wear a mask anytime he work in the shop lol.

I made a lot of researchs regarding filtering and health effects of manufacturing, honestly, I coudn’t find many studies, so I had to resort to read a lot of experiences of individual, some weren’t pretty, but most people are fine althought they know they are taking a risk. Genetics plays a big role too.

It’s up to each to do what they want, I would rather trust my common sense.

Regarding alcohol I would think that it’s less dangerous, but I woudn’t go as far as saying it’s good. It is still a poison.

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(Vince) #20

I’m not sure if you really know how much alcohol is being used…my max consumption rate is around an ounce per hour. Even drinking straight vodka… that’s not even enough to get drunk.

I can guarantee you that fumes from wd40 are 1000% worse than a minimal alcohol setup when used correctly.

Its understandable to be scared of something new, and common sense is great, most people don’t have enough. However, @The_real_janderson and I have actual use experience. Personally ive put gallons and gallons through my system without a single issue or even sign of “fumes”.

Alcohol is different than most yes.

But imo, it can be very safe to use and a very effective coolant/lubrication for a cnc router.

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