Thread: Cutting oil advice

After not using my Beaver MK2 mill for some time I find the cutting oil has "gone off" and clogged the coolant pump impeller - can anyone advise a long life cutting oil which doesn't degrade over time ?

Originally Posted by Alf Scotting

After not using my Beaver MK2 mill for some time I find the cutting oil has "gone off" and clogged the coolant pump impeller - can anyone advise a long life cutting oil which doesn't degrade over time ?

Gday Alf. Sounds like you mean coolant. Cutting oil and coolant are not necessarily the same. You are going to get deluged with suggestions. . There are some real good water soluble coolants around with prices ranging from reasonable to "sell your first born" high.
All this stuff is made for use in machines that are running almost every day in a machine shop. In a hobby machine that might not get used all the time, it can be a problem as you have found. I'm currently in the process of setting up a mobile coolant tank/pump system for use on both my lathe and mill. Just in an effort to reduce the amount of coolant I have mixed at any time.
I recently bought some coolant (the name escapes me atm) but I have yet to use it. It got good reviews and was a reasonable price.
I can post the name tonight.
meanwhile let the fun begin
regards
Peter

Originally Posted by Alf Scotting

After not using my Beaver MK2 mill for some time I find the cutting oil has "gone off" and clogged the coolant pump impeller - can anyone advise a long life cutting oil which doesn't degrade over time ?

There is no such thing. Best we have ever got at work was 2.5 years, and that is with proper maintenance. For good coolant life, the sump needs to be free of chips, tramp oil needs to be skimmed off, and concentration needs to be maintained at the correct level.

Ash, is there a simple/ cheap way of testing concentration?
I should probably get a test plan set up for the grinder at work.

Michael

Alf
Synthetic coolants will probably last longer than the traditional soluble oil and water, but even they have a limited life as Snapatap has said.
There are alternatives but you need to have deep pockets.
Inox is supposed to be pretty good as a total replacement for soluble types however its pretty exxy. Especially when you factor in the fact that it isn't diluted.
CDA Eastland are advertising 20 Litres for $254.
I was seriously thinking about it last year but I couldn't justify the cost for what is just a hobby for me.
Some people use misters rather than flood systems, others just use a cutting oil with spray, drip or brush application.
Myself (and this is my personal preference) much prefer a flood system and I'm prepared to put up with what some people class as drawbacks with that. Mess on the floor and on the machine, losses due to evaporation etc.
If you decide to keep going with the system you currently have but with new coolant, its really important to clean your system thoroughly before refilling, to get rid of any bacteria from the old coolant.
You can (or at least used to be able to) get coolant system cleaner/sterilising fluids, but a good clean out by hand of as much of the system as you can, followed with hot water and disinfectant, running the pump for a while will probably be enough.
In another job about 25 years ago, we had 15 lathes, 5 mills, 2 surface grinders, a cylindrical grinder, a Brobo saw and power hacksaw all running soluble oil and water. It was part of my job to clean them all out every 6 months as well as clean out any that went "off"in between.
Soluble oil and water, that has gone off after being contaminated by cast iron swarf has a very "unique" smell.

Hope this helps.
Peter

Originally Posted by Michael G

Ash, is there a simple/ cheap way of testing concentration?
I should probably get a test plan set up for the grinder at work.

Michael

Michael. yes its called a refractometer. I've never used one but you can buy one from Aliexpress for less than $20. I'll probably buy myself one.
peter

Originally Posted by bollie7

Michael. yes its called a refractometer. I've never used one but you can buy one from Aliexpress for less than $20. I'll probably buy myself one.
peter

I have one and still have not used one
I mostly use the feel the coolant between the thumb and finger trick, the hows the the tool lasting trick and the how oily is the machine in the morning trick .
How to read a refractometer here https://www.coolantconsultants.com/refractometers

cheers, shed

Most of the cheap ebay refractometers are designed to measure the density of Antifreeze solutions so have SG measuring ranges from 1.0 to 1.12 (Brix scale of 0 to about 30).
At work we had an Atago refractometer specifically for cutting fluids and it has a much narrower range (1 to 1.04 SG, or 0 to about 10 Brix) and hence higher resolution.
If you look up the current price of these make sure you are sitting down first.

To accurately work out % concentration of the diluted solution requires that the refractive index of the neat cutting oil be known but the way around that is to accurate make up a recommended/known % solution (by weight) of the working cutting liquid and then use that as a reference.

If anyone spots a refractometer on ebay with a narrower range of SG than usual, then that would be worth knowing.


[EDIT] OK I honed my fleabay search skills to extract the following low % Brix scale refractometers

here's a 1-10% Brix from the US (AUS$100)
https://www.ebay.com.au/itm/0-10-Bri...gAAOSwKNhaxCVq

Heres one from China 0-10% Brix AU$32
https://www.ebay.com.au/itm/RHB-10AT...oAAOSwN5lc62Hh

Here's a 0-20% Brix AU$25
https://www.ebay.com.au/itm/0-20-Bri...UAAOSwTmtaODZa

Another for AU$18
https://www.ebay.com.au/itm/0-20-Han...0AAOSw5OxdTNIB

And a 0-5% Brix for AU$35
https://www.ebay.com.au/itm/Hand-hel...AAAOSwD8BZbCku