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Metal working - dry / lubricants / coatings / cooling mist


Ultra Member


Ultra Member
Premium Member
Rauce - You said “isopropyl or denatured alcohol on Al with carbide is less messy than WD40” That makes sense since it will evaporate quickly. But that is a flammable liquid mixed with hot chips and also a lot more stinky than WD40. Are the fumes & fire risk worth it? Dabbler mentioned that he also uses isopropyl (or methanol) but in a mist & diluted with water so I guess not nearly as risky?
Where do you source the isopropyl (or equivalent)? It’s expensive in small bottles at the drugstore, I don’t think Home Depot has it, and Amazon charges as much for delivery as for the product.

You really don’t need much when using alcohol. Same goes for WD-40 really. It helps keep chips from sticking to the cutting edge and improves the finish.

I use one of these bottles (bought from busy bee) to just squirt a bit on the surface before a pass.


I have usually just bought it in larger of the sizes you can get at drug stores/big box stores (1l I think) I don’t go through it very fast. When I tried denatured alcohol I got it from Home Depot. It wasn’t the methyl hydrate stuff though, it was denatured alcohol so mostly ethanol with just a bit of methanol to make it undrinkable.

You can definitely get isopropyl in 1 gallon containers. At my old work we got it from SB Simpson, the welders used it for cleaning.

Regarding coolants, lubricants etc. In my home shop I really just use WD-40 or alcohol on aluminum. Rapid tap on steel with HSS and nothing on steel with carbide unless things seem to be getting real hot, then I’ll use coolant in a spray bottle or with a mister. That’s pretty much it.


Well-Known Member
CWret, misting with a water soluble coolant is a bit of a throwback, useful for HSS when milling, particularly in slotting, and to avoid using flood coolant which gets everywhere on a small Knee Mill. The mist also diminishes the air quality.
Acculube became popular with micro drop “mist “ of a vegetable based oil, minute amounts and very effective at lubricating, also messes with air quality. Works well on something like stainless if using carbide endmills or HSS.
Stainless requires lower speed and higher feed in general.
Larger indexable face mills in steel are okay to run dry, they are not ordinarily run at high depths of cut in a slotting situation , especially on low powered mill like an Excello. With lighter width (1/3rd of cutter width)of cuts the carbide is exposed to a lot of open air and has a chance to cool down or at least not build up more heat due to workpiece contact area.
A continual stream of air is useful for clearing the chips( enabling them to get into every area of the shop easier) .
The higher positive type of pressed chip control inserts generate a lot les heat and impact, the coatings keep more of the heat in the chip rather than transferring to the tool. I wouldn’t worry too much about coolant with indexable.
You seem to be okay on the drill end of it with the various compounds.
Both carbide and HSS endmills will survive without a coolant or lube if you pay attention to speed , feed , I wouldn’t mist carbide endmills, just air to clear chips.
It’s been mentioned before, we are not production shops, we have time and don’t need to push everything to the max.
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Ultra Member
Something important to consider coated or uncoated Carbide (or anything else for that matter). If any of the coating materials are the same as the material being worked you will get sticking as they heat. Something I had to learn the hard way and am still dealing with on a few cutters.

I only try and purchase uncoated now sacrifice a little durability in some materials but have greater flexibility in all materials.

If you look carefully a lot of the higher speed cuts are done without coatings.

Now if you really want to go the rabbit hole, CERAMIC end mills and the whole game changes again, only the dollars spent increases in everything.


Super User
Premium Member
@Rauce – I’ll get several of those BB spray bottles - looks like a good item to keep handy with different liquids (heading to BB, SB Simpson, & KBC today, watch out wallet)
Go sparingly on alcohol / WD40 – good advice.
I called SB Simpson – 1 gal. isop in stock (forget the price but I think they said about $48)
“Regarding coolants, lubricants etc. In my home shop I really just use WD-40 or alcohol on aluminum. Rapid tap on steel with HSS and nothing on steel with carbide unless things seem to be getting real hot, then I’ll use coolant in a spray bottle or with a mister. That’s pretty much it.” A good KISS summary – tks

As an ‘old guy’ using a throwback method fits right in - but I do also like to be up-to-date too. I see Acculube 2000 at Granger ($180/gal)– will keep that option in mind. SS: use lower speed, higher feed. Good/easy rule of thumb. I think my air nozzle will be getting lots of use (especially since: it is easy to re-position towards the cutting tip; easy to get out of the way when not in use; and my ultra-quiet compressor is only a bit noisier that the mill. (using a phone dB app, the mill is 68dB & compressor is 71dB when standing at my operating position + I could move the compressor a bit further away). In reference to using air and chips, you said “enabling them to get into every area of the shop easier” LOL - my shop is half of the attached garage so my wife is going to be so very pleased. You have also reinforced the ‘air only on carbide’ - that’s: easy / makes good sense / avoids thermal shock.

@Degen – pretty sure the carbide inserts I already have + the solid carbide I ordered yesterday are all non-coated, so I may have accidentally avoided that issue. I’ve heard a bit about ceramics – I’m not on that page, not looking at that book, not in that library, not in that part of town.


Super User
Premium Member
Isopropyl vs Methanol

I'm interested if anyone has a big preference between isopropyl vs methanol for a coolant.

I've forgotten most of my chemistry but here is what I've found out about these products (I got this info from the internet - so we all know that it is therefore 100% accurate!).

- isopropyl=isopropanol=2-propanol
- methanol=methal hydrate=wood alcohol=methyl alcohol
- both are miscible and mix completely with water
- isopropyl has toxic fumes but methanol is a bit worse
- isopropyl will irritate the skin but methanol is a bit worse
- isopropyl is more expensive in Canada (4 litres for $48 @ SB Simpson)
- methanol is commonly used as a gas line antifreeze and also to keep compressed air equipment from freezing. It's readily available - Home Depot sells Methal Hydrate (using trade name Solvable) 4 litres @ $14
- as a fuel (camp stove) methanol burns hotter & cleaner, isopropyl smokes & leaves soot

- rubbing alcohol is 70% isopropyl + 29% water and other oils and stuff to make it more skin-friendly
- denatured alcohol is not the same as methanol but it is similar. It is actually ethanol with methanol & other stuff added to make it undrinkable (yea, ethanol is pure booze or 200 proof)

When considering these products as a machining coolant - I could not find anything about one being better than the other. Therefore - I'm leaning towards the isopropyl because: I expect a jug of either will last me a LONG time; isopropyl is a pure product; the price is not that important if a jug lasts several years; and a bit less toxic is good.


Jack of all trades -- Master of none
Premium Member
Bought some yesterday
I use this in my windmill freeze-prevention tank. It’s also good for starting grass fires when you kick over the camp stove you made in shop class on a scout camping trip


Ultra Member
I'm surprised at how many use flamable liquids for cooling.

I use flood for grinding and horizontal milling, squirt bottle for the vertical mill. The Trim microsol is the stuff to use, it just does not go bad. Using carbide in the mill is relatively rare, when it happens, dry or some air.

I have a DIY mister I use on a tool grinder (the little bench one not made to accommodate flood). A lot misters are crap and will fog up your shop. The ideal one lets you control things to the point where you are depositing droplets on the edge of the wheel, that are travelling at about the same speed as the wheel so they land there and mostly stay put. When you get this, its fantastic. No fog and you can just about creep grind with it (huge DOC) with the mister keeping things cool.

After much research, it seemed that about the only the way to achieve this is separate pressure control for the coolant and the air with the two coming together close to the nozzle, so that's what I made.
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Always my flammables are diluted in soluable oil or other lubricant. My flammables are stored outside the shop in a metal cabinet - after all, they don't freeze. I do, however have a 14 ga tank of low odor varsol in the shop , with about 2 litres of solvent in it. But I'm not worried about that - If I were I'd be using diesel.


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Premium Member
The ideal one lets you control things to the point where you are depositing droplets on the edge of the wheel, that are travelling at about the same speed as the wheel so they land there and mostly stay put. When you get this, its fantastic. No fog

The mister I have (cheap from eBay or aliexpress, I can’t remember) allows very fine adjustment. I have a regulator and a ball valve on the air line. The mister has needle valves for the air and the coolant. I find it works well at around 20-30psi air. I have the needle valve for air set to nearly the minimum required to get the coolant drawn through. Never felt that it makes much of a fog this way. More like heavy droplets as you describe.

I use it mainly for parting and for turning stainless on the lathe. Flood would be better I’m sure but it seems to do fine.