Cutting oil -

So...........thanks for all the replies ref tap and dies this now raises the question to a beginner like me as to what advantages a branded and specific tapping oil/compound/lubricant, call it was you will, has over say WD40?

When using my die to increase the length of threads on my stainless steel bolts in my previous post I just used some silicone spray from WD40, then I tried some actual WD40 original, and some oil, I could tell no difference with my limited knowledge on tapping.

So could anyone answer me please as to how does specific tapping compounds work, what do they do except lubricate and reduce friction? What advantages do they have over say oil or WD40 please.

Gary

For cutting gummy steels a sulfur based cutting oil is generally used. I believe the sulfur provided two benefits. It improved lubricity between the tool and the work and it facilitated fracturing of the chip at the microscopic level.

Sulfurized (IUPAC changed the international correct spelling from sulphurated) and chlorinated oils create extremely active chemicals when subject to high shear loads. These bond to 'recently' cut metal and lubricate that metal. In other words, they make the chips separate from the stock far more easily, reduce cutting forces and improve the finish that can be obtained.

WD40, being mostly kerosene, has no effect whatsoever on steel, other than making it smell. On aluminium, it can have a positive effect that is similar to other light alkanes and alcohols. Silicone compounds are not useful cutting lubricants at all, since they are poor lubricants in general and have no enhanced activity in high shear conditions.

Trefolex cutting compound has sulfur and talcum plus tallow in it to help lubrication under pressure.

WD40 is as it name implies (Water Displacement #40) is not a lubricant, it is designed to get rid of water from wet metals. After that it does absolutely nothing except get sticky as the volatile constituents evaporate. It is handy for short term rust prevention and machining ali as previously mentioned.

In the bush I use something like this if nothing else is available, rendered pig fat (tallow) works pretty well although it does smell a bit. You can get some here **LINK** or hunt the pigs with a suitable calibre. I like a .444 Marlin with 12G O/U loaded with bb's as backup. Eating the rest of the pig is a bonus but cook it well as they carry parasites. Use a meat thermometer!

As you do not give a location you could be anywhere in the world so consider this as general advice!l

From reading your other thread though, it appears that you may have picked a difficult to thread lump of stainless steel wire so then I would just consider replacing with the correct bits as probably cheaper in the long run.

* Danny M *

To add to the above posts regarding the oil content of WD40, it is only around 5%, so not much use as a lubricant on steel.

And according to WD40 themselves, it contains NO kerosene or silicone.

https://www.wd40.com/faqs

Edited By David Standing 1 on 04/01/2018 07:56:26

Buy yourself a 500g tin of proper tapping compound, something like Rocol RTD(stands for reamer tap and drill) paste ( I use a cheaper brand but can't remember the name) it will last you for years and is good on all steels. I also use it on some aluminium just because it holds the swarf on the tap and is easier to wipe off than blowing a lot of mess around. As well as the above compound I use a spray of metal cutting compound from "Sterling" Other brand are available and have their uses.

How does " Duck Oil " fit in to this, I do use tallow or a tapping compound for thread cutting and duck oil to spray on my machine's shiny bits

Mick

 

I believe Duck Oil is similar to WD40 in being a carrier fluid with a grease component which I use as a quick spray on the working parts of my machines after use to keep corrosion at bay in my damp garage workshop. It has been successful at this for 6 years.

For tapping I use CT 90 tapping fluid available from EKP Supplies in the UK (amongst other suppliers, I expect). After breaking numerous small and expensive taps, usually while turning backwards to clear the swarf, while using the cheap and readily to hand oils I tried CT90 and have had no breakages since. I use it in all metals as apart from easing the thread cutting it sticks the swarf to the tap making it easier to clean.  Although it looks expensive, a drop goes a long way and  I expect the bottle I have will see me out.

Jim

Edited By Jim Nic on 04/01/2018 10:23:41

I think purpose made tapping compounds are worth the money, general purpose lube and water displacement products do not do the job in my opinion. Trefolex is my choice but others will have their preference. Using the proper stuff may be a revelation if not used before.

Mike

I see that WD40 is now being used as a brand for a range of specialist lubricants including a cutting oil for tapping etc. It looks as if we will need to qualify the product when referring to WD40.

Mike

Edited By Mike Poole on 04/01/2018 10:58:58

Mike is quite correct - get purpose made tapping lubricants. I have used Ambersil Tufcut for years it is not expensive and a little goes a long way. It is especially good for use on tough materials such as stainless steel, silver steel etc. but I use it on all materials and have not had a broken tap - yet!. One bottle is cheaper than a broken HSS quality tap or a scrapping a component with a tap broken off in it.

Eric

The MSDS states C9-C11 alkanes and isoalkanes with a flashpoint of 46°C. Pedantically, that's white spirit in the UK, but it's still a light kerosene/paraffin.

Kerosene, like other distillation fractions has a range of alkane carbon chain length (it just being a particuler fraction of the base stock). Not only is the chain length an arbitrary value, and may overlap with other fractions, the % of each constiuent can vary. Depends somewhat on the origin of the he crude oil.

WD40 looks to be more volatile than kero.

Typical Mercan obfuscation! They love to dress everyday substances up behind the protection of "trade secret". So perhaps technically it's not "kerosene" as such. But it's clearly based on a simple derivative from the fractional distillation of crude oil - one that is possibly even cheaper to source.

I've got some of the funky new WD40 "multipurpose cutting oil" and I have to say I've only used it a couple of times. Main reason being that it is a filthy brown colour and it stinks of a sort of nasty sulphurous pong. For tapping etc I use Rocol and for turning without flood lubricant I just use std WD40. Unlike said "specialist" WD40, it gets the job done without threatening your sense of smell.

Despite Mark Rand's explanation above (which I'm not arguing with), I find that WD40 can help with some steel turning operations such as parting off. I'm now down to my last 2 gallons which I acquired for peanuts in Canada.

Murray

I have a 1lb tin of Texamol and have been using it since 2002. So far, I've had no tap breakages or dies wear out. Better to use the stuff designed for the job. I know in Aluminium many of my work colleagues on the shop floor only use tallow while tapping. But steel of any sort, it's always Texamol or Rocol.

Regards,

Richard.

Just a short note to thank you all for your kind replies. Especially Mark, great explanation the sort of thing I was after.

Ok answers absorbed and committed to memory.

Looks like I will be purchasing some of the branded stuff after all, now which one to choose is another question ...but to choose is a must.

Thank you

Gary