Thread: Home made cutting oil

Hi Keith,

I do remember a discussion about this some time back. A thread search may so it up?

Simon

Not sure if there is truly a difference between coolant and cutting oil or whether you are using it as a general term for coolant but a search so far has these:
https://www.woodworkforums.com/f65/co...native-141476/
https://www.woodworkforums.com/f65/wh...oolant-152986/ (post #10 onwards)


That's about all I could find with a 10 minute search….

Simon

Originally Posted by simonl

Not sure if there is truly a difference between coolant and cutting oil

There is. As I understand water is about as good as you'll get as a coolant. Its also a lubricant but not a very good one. Its cheap and doesn't make much mess(other than turning some things a nasty brown colour). Work stays cooler(or you can drive things harder if you have the HP) but the tooling wont last as long. Oils on the other hand are good lubricants but arent nearly so good at cooling. Cost more, makes more mess but rust isn't an issue and tooling should last longer. Emulsion coolants are somewhere in between the two.

I dont recall seeing a recipe for cutting oil. At its simplest (so I've read, never tried it) coolant used to be soap and water, though I doubt many would recommed it. I'd think making a emulsion coolant would be a job for BobL.

Not much help for Keith though.

Stuart

You cannot make it any cheaper and better then the bought stuff...

I certainly would not use a home brew cutting fluid on an expensive tap or die or other expensive tooling..

A piece of easily sharpened HSS might be a different story... But a $20 spiral fluted tap.. No way...

Guy Lautard offers two recipes in his Machinist Bedside reader books
The recipe for straight cutting oil is based on lard, turps and graphite sounds messy and very unattractive.
The recipe for coolant/lube uses borax, water, soluble oil and sodium triphosphate has the advantage that it is not supposed to go off and stink like a lot of home made recipes.
I don't know if I would like it sprayed around the place which is what tends to happen when using the lathe.

Personally I agree with RC, after experimenting with a few different things I found the bought stuff is so much better that I would definitely buy it again when needed.

I bought a tub of Trefloex about 5 years old and I still have ~3/4 of the tub so even though it was expensive it should last a long time.
For the lathe I use the synthetic soluble oil from H&F.

I have only ever used home made cutting oil.

It's just 4:1 ratio of kero and engine oil.

Works quite OK and wont cause rust, or give you dermatitis.

Much the same as WD40.

Only downside is that it smokes a bit when things get hot. Just run the fan a bit faster when that happens

Rob

One problem with using all purely oil based coolants is that the specific heat of oils/kero/turps/ATF is less than half that of water based coolants so the ability to absorb and remove heat is correspondingly less. This cannot just be over come by using more coolant because there is usually a specific contact area generating the heat during the cutting process.

The only time I have rust probs when using water soluble oils is when I start to skimp on the amount of water soluble oil being used.
If I stick to the right ratio I don't have a problem.

If by cutting oil you mean emulsion coolant, this is a DIY receipe:
How to Make Cutting Oil | eHow

If by cutting oil you mean straight cutting oil, just use plain hydraulic oil.

If you mean for things like tapping, forget oil - there is nothing better than some leftover lard. Or treat yourself to a duck breast; pour the oil that comes out in a jar and let it cool. It becomes a fat that not only tastes great on bread, it also lends itself perfectly for tapping and your workshop will smell like a 5 star kitchen. Chris

It's interesting looking on YouTube at what is used for cutting oil around the world.

I've seen more than a few Romanian, Ukraine and Russian machinists using what appears to be old sump oil - black gold.

When money's tight, I suppose you soon find out what works and what doesn't.

Rob

Originally Posted by cba_melbourne

your workshop will smell like a 5 star kitchen. Chris

Serving hot chips all day long..

Ray

Originally Posted by cba_melbourne

. . . . . If you mean for things like tapping, forget oil - there is nothing better than some leftover lard. . . . . .

This reminds me of coming home from school as a kid , starving, and nothing in the pantry except bread.
Head for the lard jar under the sink.
It usually still had some crispy bits left over from the previous use, spread on bread and top with salt and pepper . . . . . . .

Originally Posted by BobL

It usually still had some crispy bits left over from the previous use, spread on bread and top with salt and pepper . . . . . . .

mmmmmm yummy. Of course we arent allowed anything like that these days.


"A great deal of heat is generated in the cutting process, so a fire extinguisher should be kept handy as a precaution against the oil catching fire in the cutting process. When using this cutting oil, cutting machines should be set to a slower speed."

Now there is something I've not seen before. Could you really set something thats 80% water alight?

Stuart

Thanks for your help. I will try your ideas and see what suits.

Cheers
Keith

Originally Posted by BobL

It usually still had some crispy bits left over from the previous use, spread on bread and top with salt and pepper . . . . . . .

we must have been poor cos all we had was dripping spread on bread with either sauce or salt n pepper or some times all three