To oil or not to oil

[David ColwillParticipant @davidcolwill19261]

Posted by Oily Rag on 12/02/2021 19:57:16:

Posted by Oily Rag on 12/02/2021 17:06:05:

Does anyone still use milk?

Patient to Doctor: Doctor I keep being ignored!

Doctor: Next!

Seriously does anyone still use milk for machining copper or aluminium? I have an old Frederick Bates, Stirchley, Birmingham (phone Kings Norton 2266/7/8!) tap and die set which lists the following lubricants and materials for tapping:

Wrought iron, steel 0.1% through to 0.6% -> rape oil, paraffin, lard or whale oil (I take it that lard is also known as Russian Fat)

Cast iron(!) malleable and cast steel -> soluble oil and water emulsion

Tool steel -> As Wrought iron

Nickel / Chrome and stainless steels -> Turps or emulsion oil, or Turps and white lead

Copper -> Milk

Bronze -> Rape oil or Emulsion oil

Brass (soft, medium or hard) -> Rape oil or emulsion oil

Aluminium or Silium -> Methylated spirit, paraffin, milk, or paraffin + rape oil

Bakelite -> Paraffin

Some interesting old lubricants there as well as materials, love the Bakelite and Silium! Now where can I find some whale oil?

Martin

Yes!

I use:-

Skimmed milk for most general machining.

Semi skimmed for non ferrous.

Full fat for Tapping and reaming.

Gold top for exotics.

For heavy turning on the lathe I have a cow (Daisy) connected via a milking machine, the sump is fed directly to a latte machine.

Errr actually no. I'm sure that I have read this somewhere but thought that it might be an old wives tale. Did the instructions on the box give any clue as to how to overcome the smell after a couple of weeks? I have been a doubter of these old recipes until quite recently. I was complaining about tea stains in my cup (as you do) when someone said " fill the cup with hot water and add a teaspoon of sodium bicarbonate" as I already had some I tried it. Amazing it actually works.

David.

[JasonBModerator @jasonb]

I have actually used milk for tapping copper No problem with such small amounts going rancid and doubt many would pump it through a coolant system. Though I expect many of the modern lubricants would do as good or better than the old liquids. As as for full fat well you can't get much more fat content than tallow which still seems to get used.

Andrew, you say you would not use coolant on a minilathe but what about lubricant? eg paraffin on aluminium or an RTD when doing those three things.

[Pete WhiteParticipant @petewhite15172]

Posted by Andrew Johnston on 12/02/2021 19:57:39:

In simple terms neat cutting oils provide lubrication and not much cooling, whereas soluble oils provide cooling and not much lubrication…..

Says quite alot to me, I have tanks and pumps, but don't use them anymore, a brush is my choice. I am not in a hurry these days, even to remove lots of metal. However careful I was always ended up with getting splashesd, cant forget the smell from the old fashioned stuff.

[SillyOldDufferModerator @sillyoldduffer]

Milk and suds are close relatives – both are oil emulsions, milk containing edible fat rather than an oil. Milk is a good cutting fluid.

The obvious problem is the powerful stink when milk goes off. Easily tested: pour 20ml of fresh milk into a folded clean towel. Measure how long it takes for the stench to become unacceptable when the towel is hidden under a bed. Tolerance varies; a heavy smoker with a poor sense of smell might not notice until the neighbours complain. Males not being noted for scrupulous hygiene means She Who Must Be Obeyed will notice sour milk much faster than the average bloke.

Second problem is sour milk is crawling with bacteria. Don't get it in a cut! Not so bad now we have antibiotics, but in the good old days the infection often ended in amputation.

Dave

[robjon44Participant @robjon44]

Hi all, nobody has mentioned using chainsaw oil, something I learned on here years ago, its thixotropic so only liquid at the cutting point, doesn't fling, drip etc & the bottle I purchased by Stil will last 2 lifetimes in a home workshop.

Cheers, BobH

[Anonymous]

Posted by JasonB on 13/02/2021 08:28:16:

….you say you would not use coolant on a minilathe but what about lubricant? eg paraffin on aluminium or an RTD when doing those three things.

I don't turn aluminium very often, as it isn't used on my traction engines, other than for machining fixtures. I find that the CCGT inserts work fine without the need for coolant. Birdsnesting of the swarf is a bigger problem, and I don't think coolant would help with that. I don't use RTD very often, mostly for large taps or tough materials, and only when things get iffy. It works very well but is a PITA to clean off. An advantage of using larger tapping drill sizes than most modellers is that tapping is much easier without the need for messy lubricants in most cases.

Andrew

[Howard LewisParticipant @howardlewis46836]

FWIW

When the lathe was installed back in 2003 the intent was to have pumped soluble oil. The aquarium pump still sits on the shelf.

For Tapping / Dies Apologies to vegans, but bacon fat, or Rocol RTD.

For almost everything else steel, dry. Except for parting off: a gravity fed tap and nozzle on a small magnetic base to drip onto the tip of the tool.

Occasionally, WD 40 onto Aluminium, but mostly dry..

Occasionally neat cutting oil.

On the mill, mostly dry, but often neat cutting oil on slitting saws., despite the smoke

Howard

[Nigel Graham 2Participant @nigelgraham2]

Bill –

WD-40. Yes. it's meant to leave a residue, though it's not the lubricant many think despite the waffle on the can. (WD stands for "Water Dispersant".)

Perhaps WD-40 has become a popular cutting-fluid by becoming easier to obtain than paraffin.

'

Andrew –

No, I don't think I did ask him! I suppose it's what he thought appropriate for the turning he was doing – small components mainly of EN1A, plus a fair amount of aluminium, some stainless-steel and occasionally brass.

Stainless-steel rounds were used extensively in the company's machines for small shafts and pivot-pins.

The hack-sawing machine I operated was a hefty Wicksteed one, later replaced by a Kasto thing. That had a roller-vice designed to crush swarf and its own turning-marks into the material surface, to the millers' frequent disgust. As I recall the Wicksteed had no coolant but the Kasto did. I used the conventional stuff that forms white "suds" until the company started buying a modern soluble fluid, mainly for the NC machines, but fine in the saw for all metals.

'

Dave –

Don't remind me of sour milk…..

I regularly took milk, tea for the use in, in a small ex-medicine bottle to work each day. Then one day I could not find that bottle. I searched everywhere – work, home, car. Like the Chord and Michael Flander's French Horn, it "…. had gorn. " . Some months later I saw a curious bulge in the car's front nearside carpet. Yes – the bottle, slipped down behind the parcel-shelf. Needless to say, I binned it unopened.

However….

Once I managed to lose about half a pint of loose milk into the carpet in the back of the car. It's an excellent way to measure the absorbency of car carpets and the number of ponding points in the floor-pan. Despite lots of washing it took about three weeks for the car to stop olfactorily reminding me of the school changing-room.

Then what happened on Week Four?

I managed to lose about half a pint of loose milk into…

[Bill PudneyParticipant @billpudney37759]

Just remembered….coconut oil. A friend of mine used to run a business making dental implants from grades 2 and 5 titanium. Typically he used very sharp HSS cutters and coconut oil, especially when cutting threads. From memory all the parts he made were under 6mm diameter and less than 12mm long. I have subsequently used coconut oil on just about everything, especially threads it certainly does work!! It needs to be kept warm to stay a liquid. When it's at the right temp which seems to be over about 35 degrees C it is at it's best. Apply with a small brush, it doesn't take much to make a difference!!

cheers

Bill

p.s. I used a concoction including Turps on the mill. Now the mill and vice are missing large areas of paint.

[Anonymous]

Posted by Nigel Graham 2 on 13/02/2021 22:32:56:

No, I don't think I did ask him!

That's a shame, a missed opportunity. An apposite idiom given the current discussion would be no point in crying over spilt milk.

Andrew

[IRTParticipant @irt]

I have been using CT-90 when turning steel.

I have been having minor intermittent problems with breathing which I had put down to an allergy to something.

Yesterday I was taking quite aggressive cuts in stainless steel that generated a lot of smoke.

Walking the dog later, my breathing again tightened and I developed a cough that went on all night.

Looking at the data sheet for CT90, there is no great emphasis on risk from fumes although it does mention adequate ventilation.

Does anyone else suffer this sore of reaction to cutting oil fumes?

Maybe this is something else that should be taken into account when deciding if cutting oil is to be used?

[Anonymous]

Looking at the datasheet it doesn't seem to be intended for general machining. It contains high pressure additives for slow, but potentially high pressure, operations like drilling, reaming and tapping. The fact that it is available in aerosols should tell you that flood coolant for general machining is not it's primary purpose.

The safety sheet mentions toxic fumes from combustion, so if you're getting smoke then you are asking for trouble. Use it properly and look for another product for general machining.

It seems to be an equivalent to the Rocol RTD compound I sometimes use for tapping. No way I'd use RTD for general machining.

Andrew

[Nigel Graham 2Participant @nigelgraham2]

Some cutting pastes and fluids do bear labels advising against using them for machining, but I don't know if CT-90 does.

I used an engraving-machine in one previous employment. This was normally used dry because we filled the engraving with thick enamel paint, dabbed in with a slip of thin card folded into a crude nib.

One day I had to engrave some acrylic, and though it gave no visible smoke and only a slight, rather sweet odour, it was emitting something that gave me a horrible choking sensation. I did report it to the foreman who came up to the small roof-space room, but he could not understand the problem as there was no tangible evidence of anything amiss.

I just had to carry on, but carefully.

So there are things best not breathed in; and I suppose one approach without panic is to consider that if it not something we would inhale naturally, it might not be good for us.

I hate to think what solvent and lubricant vapours, coal-fumes, welding-smoke, "cordon-noire" cooking fug and steam-oil I've breathed over the years…

[Author]

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