Coolant- when to use

[KTMer]

New lathe user/owner here. I've been watching YT videos and sometimes cuts are made dry. When is coolant recommended?

 

[m-lud]

New lathe user/owner here. I've been watching YT videos and sometimes cut are made dry. When is coolant recommended?

I don't think there is a simple cut and dry direct answer. Others here may have suggestions to add.
Here is a list of Threads pertaining to the coolant subject that Texasgeartrain posted in another recent thread.
Here: https://www.practicalmachinist.com/...lant-cutting-oil-options.404230/#post-3953548
Good reading

Texasgeartrain said:
Some pretty good threads and an article here on PM:

How to Select and Maintain Machine Coolant [Updated 2020]​

Working with the right coolant will allow you to machine parts smoothly and avoid issues, but selecting the right one can be challenging.
www.practicalmachinist.com

Want to use oil as a coolant​

After hearing and seeing what water soluble coolants can do to machines, I'd like to use oil instead, but which oil? I'm cutting mostly brass and aluminum, and occasionally steel. Would something like WD40 work? If not, what would?
www.practicalmachinist.com

Best general purpose coolant​

What in your opinion is the best general purpose coolant in a job shop atmosphere where you would be cutting every type of material imaginable? We cut everything from basic aluminum all the way up to exotics... tantalum, super duplex, nitronic, Inconel, you name it at some point we cut it.
www.practicalmachinist.com

Advice for a good general cutting oil?​

Hi all - so I've been using various oils I have laying around and quite frankly I want something meant for what I am doing. I have a small Grizzly lathe that I cut stainless and aluminum on. Looking for something decent thats available through amazon or mcmaster or grainger or such. Any...
www.practicalmachinist.com

Cutting oil vs water soluble​

I know there are applications for both depending on materials etc. But, Just for the sake of conversation, which is preffered for general use and most importantly the best for the machines overall well being? I have worked in precision missle aircraft shops dealing with the space age...
www.practicalmachinist.com

Coolant or cutting oil ??? I'm on the fence.​

I have a big Warner & Swasey #5 turret lathe with the 4" capacity collet system. I've been running coolant in the machine, but I'm unhappy with the coolant because it's making the machine start to get sticky and I've had some rust issues. Also, I've got a 4" aluminum job in there right now with...
www.practicalmachinist.com

Coolant vs cutting oil while machining​

My question relates to the coolants used on lathes and other machinery. Since some coolants are diluted with water does that combination cause problems for the lathe itself in the form or rust and corrosion down the line? Is it better to pump coolant or cutting oil while machining?
www.practicalmachinist.com

Oil as coolant​

Good day boys, got a mind bending question about coolant. I have a LeBlond Regal which is my baby and I need to hook a coolant pump for it but I want to use straight oil. I never want to see H2O anywhere near this machine. I know my Hardinge CHNC ran straight oil before I switched it. So I...
www.practicalmachinist.com

 

[Don's Engine]

That's a ball of worms right there. I would follow M-lud's advice and start doing some reading/youtubing.
Just a general rule of thumb. Never on Cast iron. Small jobs that are going to be quick and you're using inserts or carbide don't usually require it. Metals that hold heat like stainless are good candidates, and jobs that require real tight tolerances, require a lot of cutting and will expand from heat - then use it. Manufacturing and repair are different animals, and I'm only looking it at from the repair end. Just my 2C . Don

 

[KTMer]

I don't think there is a simple cut and dry direct answer. Others here may have suggestions to add.
Here is a list of Threads pertaining to the coolant subject that Texasgeartrain posted in another recent thread.
Here: https://www.practicalmachinist.com/...lant-cutting-oil-options.404230/#post-3953548
Good reading

Texasgeartrain said:
Some pretty good threads and an article here on PM:

How to Select and Maintain Machine Coolant [Updated 2020]​

Working with the right coolant will allow you to machine parts smoothly and avoid issues, but selecting the right one can be challenging.
www.practicalmachinist.com

Want to use oil as a coolant​

After hearing and seeing what water soluble coolants can do to machines, I'd like to use oil instead, but which oil? I'm cutting mostly brass and aluminum, and occasionally steel. Would something like WD40 work? If not, what would?
www.practicalmachinist.com

Best general purpose coolant​

What in your opinion is the best general purpose coolant in a job shop atmosphere where you would be cutting every type of material imaginable? We cut everything from basic aluminum all the way up to exotics... tantalum, super duplex, nitronic, Inconel, you name it at some point we cut it.
www.practicalmachinist.com

Advice for a good general cutting oil?​

Hi all - so I've been using various oils I have laying around and quite frankly I want something meant for what I am doing. I have a small Grizzly lathe that I cut stainless and aluminum on. Looking for something decent thats available through amazon or mcmaster or grainger or such. Any...
www.practicalmachinist.com

Cutting oil vs water soluble​

I know there are applications for both depending on materials etc. But, Just for the sake of conversation, which is preffered for general use and most importantly the best for the machines overall well being? I have worked in precision missle aircraft shops dealing with the space age...
www.practicalmachinist.com

Coolant or cutting oil ??? I'm on the fence.​

I have a big Warner & Swasey #5 turret lathe with the 4" capacity collet system. I've been running coolant in the machine, but I'm unhappy with the coolant because it's making the machine start to get sticky and I've had some rust issues. Also, I've got a 4" aluminum job in there right now with...
www.practicalmachinist.com

Coolant vs cutting oil while machining​

My question relates to the coolants used on lathes and other machinery. Since some coolants are diluted with water does that combination cause problems for the lathe itself in the form or rust and corrosion down the line? Is it better to pump coolant or cutting oil while machining?
www.practicalmachinist.com

Oil as coolant​

Good day boys, got a mind bending question about coolant. I have a LeBlond Regal which is my baby and I need to hook a coolant pump for it but I want to use straight oil. I never want to see H2O anywhere near this machine. I know my Hardinge CHNC ran straight oil before I switched it. So I...
www.practicalmachinist.com

Thank you. Lots of food for thought there

 

[KTMer]

That's a ball of worms right there. I would follow M-lud's advice and start doing some reading/youtubing.
Just a general rule of thumb. Never on Cast iron. Small jobs that are going to be quick and you're using inserts or carbide don't usually require it. Metals that hold heat like stainless are good candidates, and jobs that require real tight tolerances, require a lot of cutting and will expand from heat - then use it. Manufacturing and repair are different animals, and I'm only looking it at from the repair end. Just my 2C . Don

Thanks for the 2Cs Don

 

[guythatbrews]

Never hurts to do some reading, if you can find a book these days.

Be wary of YT. Some good stuff but some bad stuff. Any idjut can post a video and many do.

 

[Gordon Heaton]

I have a much simpler system for deciding when to use coolant. If I need to hog off a lot of material I use coolant. If I need to keep the part relatively cool, I use coolant. It lets me work faster and extends insert life. On my manual lathe it is also slightly messy, so if neither of the above apply, I cut dry.

 

[tailstock4]

New lathe user/owner here. I've been watching YT videos and sometimes cuts are made dry. When is coolant recommended?

When I’ve used water soluble coolant in the past, it was for three reasons. 1) To maximize tool life. 2) To utilize the full horsepower of a machine – assuming it has enough horsepower to be relevant. 3) To control thermal expansion. In other words, when time is money.

If the time is your own, I would use a bottle full of cutting fluid and a little brush. Coolant for the occasional user can be problematic.

It tends to collect way oil or tramp oil which forms a layer on top. You then need a skimmer to remove the oil. If the machine tends to sit, the coolant will eventually separate, the skimmer will remove that and then you’re left with a diluted coolant. To avoid some of this you’ll need an aerator to keep the coolant mixed and the bacteria out. If you don’t keep up with it, you’ll have corrosion issues.

Anyway, it is not as simple as it may first appear.

In my shop I use coolant in a cold saw and zip/miter bandsaw.

 

[KTMer]

When I’ve used water soluble coolant in the past, it was for three reasons. 1) To maximize tool life. 2) To utilize the full horsepower of a machine – assuming it has enough horsepower to be relevant. 3) To control thermal expansion. In other words, when time is money.

If the time is your own, I would use a bottle full of cutting fluid and a little brush. Coolant for the occasional user can be problematic.

It tends to collect way oil or tramp oil which forms a layer on top. You then need a skimmer to remove the oil. If the machine tends to sit, the coolant will eventually separate, the skimmer will remove that and then you’re left with a diluted coolant. To avoid some of this you’ll need an aerator to keep the coolant mixed and the bacteria out. If you don’t keep up with it, you’ll have corrosion issues.

Anyway, it is not as simple as it may first appear.

In my shop I use coolant in a cold saw and zip/miter bandsaw.

I like it!

 

[marka12161]

If you're a new lathe owner, i'll assume you are a hobbiest (like me). In that case, you might want to differentiate between coolant (primarily to remove heat) and cutting oil (to lubricate the cut). As others have said, the material matters as does the cutting tool. I use HSS almost exclusively and one of the main failure modes of HSS is for the material you are cutting to weld itself onto the cutting tool which tends to ruin the surface finish. Cutting oil (on steel) reduces this weld build up, extends tool life and improves surface finish. It does provide some cooling as evidenced by the smoke it creates but I think the primary purpose is to lubricate the tool. I just use a chip brush with oil on it for each pass. I have no experience with soluable cutting oils so i'll not speculate on those.

Do not use oil on cast iron, brass or bronze.

 

[KTMer]

If you're a new lathe owner, i'll assume you are a hobbiest (like me). In that case, you might want to differentiate between coolant (primarily to remove heat) and cutting oil (to lubricate the cut). As others have said, the material matters as does the cutting tool. I use HSS almost exclusively and one of the main failure modes of HSS is for the material you are cutting to weld itself onto the cutting tool which tends to ruin the surface finish. Cutting oil (on steel) reduces this weld build up, extends tool life and improves surface finish. It does provide some cooling as evidenced by the smoke it creates but I think the primary purpose is to lubricate the tool. I just use a chip brush with oil on it for each pass. I have no experience with soluable cutting oils so i'll not speculate on those.

Do not use oil on cast iron, brass or bronze.

Thanks marka
Yup. No only hobbiest but total noob at that!
Appreciate your words of advice- very helpful
They prompt me to ask why you choose to use HSS tooling almost exclusively

 

[marka12161]

Hmmm; why use HSS exclusively...?

Well there's lots on contnet on YouTube extoling the virtues of HSS such as:

• It's cheap
• It comes in many different sizes
• You can grind it to any form you want
• It's easy to resharpen and hone
• It's less brittle than carbide therefore less prone to chipping
• It pairs well with the old, slow machines I have

However, for me there is an additional factor and that is, I just find grinding tooling by hand to be both challenging and cathartic. It's rewarding to get the tool to perform the way you want it to.

 

[KTMer]

Hmmm; why use HSS exclusively...?

Well there's lots on contnet on YouTube extoling the virtues of HSS such as:

• It's cheap
• It comes in many different sizes
• You can grind it to any form you want
• It's easy to resharpen and hone
• It's less brittle than carbide therefore less prone to chipping
• It pairs well with the old, slow machines I have

However, for me there is an additional factor and that is, I just find grinding tooling by hand to be both challenging and cathartic. It's rewarding to get the tool to perform the way you want it to.

All good reasons to go with HSS but it seems to me that as a beginner I can start making things more quickly with carbide inserts
Do you agree?

 

[marka12161]

Call me a purest but i think there's much to learn about tool geometry (and therefore insert selection if you choose to go that way) by learning to grind tools. You can grind a 3/8" HSS tool blank into a general purpose turning tool on a bench grinder in maybe 15 minutes from scratch. If you screw it up, grind off the mistake or turn it around and start over. Boring bars, threading, radius, parting, grooving and trepanning tools are all literally at your finger tips once you learn to grind your own tool bits. My advise is spend your money on a good baldor bench grinder. Mine has a pedestal and dust collector to keep the mess to a minimum. You'll use it to sharpen drill bits as well.

 

[Gordon Heaton]

Its good to know how to grind a tool, but there is also a great deal to know about insert geometry and selection. everything that can be done with HSS can be done with carbide and a diamond wheel. Using carbide often results in doing the job without the need for insert change or sharpening.

 

[KTMer]

Good points by both marka and gordon
I'm leaning toward carbide just because I think I'll get to the point of making parts that I need quicker
A concern that I have going this route is that I've read that old machines like mine turn too slowly for carbide inserts
Is that true?

 

[Gordon Heaton]

They turn too slowly to take full advantage of the possibilities, that's all. I routinely single-point below 300rpm with carbide and get beautiful threads. Often, turning slower will give better chip fall than faster. Finish-wise, increasing the depth of cut and/or feed rate can make up for some loss of rpm. In that case be sure to use a radius-tip insert.

 

[marka12161]

To elaborate a bit on what Gordon said, with the advent of carbide tooling, machine speed and horsepower went up to take advantage of the heavier cuts and higher cutting speeds carbide allows. Look at the top speed of one of the 16-18 inch swing american production lathes (Monarch, Lodge & Shipley, LeBlond etc) in the late 30s and early 40s and you're likely to find top spindle speeds in the 600 - 750 RPM range with horsepowers in the 5 - 7.5 HP range. During the mid 50s, those same manufacturers were offering similarly sized machines with spindle speeds well above 1000 RPM and horsepowers in the 10 - 15 HP range. When you run a business, it's all about production capacity. For us hobbiests, not so much. The older, slower, lower HP machines are cheaper and most importantly, easier to power than the newer faster machines.

 

[KTMer]

Good info
I had read that some change the motor out for something that turns faster but sounds like I can cross that task off my to do list

 

[cyanidekid]

on YouTube, coolant or cutting oil is often omitted because it would mess up the shot. smoke obscuring the action, splatter on the lens.

the pros will often state that. " I turned off the coolant for the shot..."

forget wd 40, its a waste product, neither solvent nor lubricant that someone added cheap nasty perfume to and came up with a clever marketing idea for.
some use it on aluminum, but I only use it to start garbage fires when I get it free, the wind is blowing, and nothing else is available.

I use Acculube 2000, its a" vegetable based" (so it claims) cutting oil. im looking for something else on the machines because its expensive and dries into a hydroscopic varnish. I don't do production work, needless to add, id use coolant obviously if I did.