Thread: Modified coolant/cutting fluid

I was always under the impression that the fluid should be as thin as possible so that it is constantly swept or runs into the cutting edge.

The issue with vege and mineral oil based materials (including turps) is that they only have about 1/3rd to 1/2 the heat capacity of water so if oil is used then theoretically twice as much should be used. However, the ability to cool is often restricted by the geometry of a situation so it doesn't always work out that way.

Have you thought about the possibility of a fire?

Funny you should mention that Bob, it passed my mind as well and I cannot say I conducted any test on it other than drilling a lot of holes.. The drill ended up burning me when I pulled it out so it was on the hotter side of how I usually end up working..
I have read a few articles on people using kero mixed with waste motor oil as a cutting fluid. It's a guess but I think kero has a higher flash point than turps but it was on my list to look up. I was not keen on using waste motor oil as I have read you have no real control over what additives have found their way into it.
Again, it's a wild guess but the small amount of smoke from proper cutting oil and turps would be less noxious than a small amount of smoke from an unknown waste motor oil and turps.

And for god sakes Bob, don't brink up the bloody dust extraction thing again mate!

Just in case that last line gets misunderstood, It was honestly a light hearted joke Bob! Have a chuckle with me on that one!

Thanks for the comment about it being as thin as you can get it! I'm surprised i did not take a closer look at it before. The thinner oil is proving much better.

Any thoughts on it being more flammable Bob?
I can't say I have ever read of anyone setting a lathe or mill on fire before.
I can tell you that if I'm the first, I will take some pics and post them up here with a red face!

After by no means an exhaustive search the autoignition temperatures reported for turps on the web seem to range from about 200 to 300ºC while those for Kero range from ~230 to 315ºC.
I can understand the variability for turps given that it is a variable material but can't see why Kero should vary that much

The reported flash point temperatures for these materials seem to vary widely as well with Kero being perhaps mostly slightly higher .
Based on this there's not much difference between the two.

Waste motor oil lis a complete no-no for me.

Hi Bob,

Wouldn't water coolants also have a huge advantage from phase change?
Though maybe phase change of the turps explains some of the improvment noticed but the OP over straight oil?

Stuart

Originally Posted by Stustoys

Hi Bob,

Wouldn't water coolants also have a huge advantage from phase change?
Though maybe phase change of the turps explains some of the improvment noticed but the OP over straight oil?

Stuart

Could be, water has a 10x greater latent heat of vaporisation than turps.
Turps has a lower specific heat so it will heat up much faster than water and it also boils at only around 65ºC so it's more likely that phase changes plays a role for turps than water.

Unless there's steam being generated then there is not usually a lot of phase change happening when water based coolant is being used. I guess if the steel is blueing temps even under water coolant stream then phase change is important.

BTW even though the BP of turps is 65ºC, the flash point (temp needed to generate a vapour that can be ignited) for turps can be as low as 35ºC so if you are boiling turps I would be a little careful and use ventilation

I think you are wise to consider the fire possibilities. I am inclined to doubt that hot swarf will ignite your mix as I doubt that the residual fluid on your table etc will be heated sufficiently to reach auto ignition. I would be a little more concerned, or at least give more thought to an open container of your mix being ignited by an external source in a workshop situation. Perhaps an oil can may be a more appropriate vessel?
It must be a fairly messy fluid to use in practice with a lot of oily residue left. How do you clean up your finished components?

An oil can would be better as it's mostly closed up but I prefer to use a small acid brush for adding cutting fluids.

I use quite a small pot.....actually, it's a 50ml plastic specimen jar with a magnet dropped in it so it does not topple over and it's stuck to the top of my drill press. I keep it under half full as it's the right height for the bristles. The magnet keeps the swarf out of the brush as well.
So at a guess, it's 8mls of turps, 12mls of cutting oil and about 5mls for the magnet. It's not a whole lot of fluid on hand. You are right, the turps will just evaporate off. My workshop is very drafty and pretty darn big. If I was in a basement with no ventilation I think I would be avoiding it to be honest.

Cleanup....well I guess you could call it messy. It's about the same as with any cutting fluid really. The cutting oil is water dispersable so parts just get a wipe with a dry cloth or a proper scrub if I'm painting them.

The turps evaporates off pretty fast once it's crept over the part due to heat and the increased surface area. What's left over is the cutting oil which keeps the rust down until I clean it up for paint.

But your right! A fire hazard is something not to be taken lightly. I'm always conscious of that as I weld and grind in here along with a lot of different flammable products around the shop.

I store my bulk fluids on the other end of the shop for that reason. I keep quite small bottles on hand this end for daily use. Actually, I try and keep the workshop tidy.... It feels a bit safer and I'm less likely to knock things over!

I'm going to keep this mix for the drill press only as it appears to flow to the cutting end much easier.
No one else appears to be using 'HillBilly' cutting fluid mixes....I'm going to take that as a silent hint fellas and look for a better option!

I use tap magic for all my drilling. I can go through 40mm with a 5mm drill without backing out, and all it takes is one drop of tap magic. Best stuff ever, and yes it is not cheap but I bought a can for $30 or so about 7 years ago and it is still half full.

Ew

Ueee, that's some pretty darn good advice! I might pick some of that up. I have looked at it in the past but have been waiting for my other tapping fluid to run out.

On a side note though, I just googled the MSDS on tapmagic.
Maybe someone else can take a look at it as it is a bit cryptic but it looks like it's 10% tap magic with 90% paint thinner.......maybe I read it wrong?

I was going to put down butyl acetate, but I could not be assed to spell it right!....I had a crack at it anyway!

If it's cutting oil and thinner, it puts me back into the cutting oil and turps bin again.

Now I'm doubting that I interpreted the MSDS properly!.....someone with a red pen will check it for me please!?

Originally Posted by Ueee

I use tap magic for all my drilling. I can go through 40mm with a 5mm drill without backing out, and all it takes is one drop of tap magic. Best stuff ever, and yes it is not cheap but I bought a can for $30 or so about 7 years ago and it is still half full.

Ew

Me too... I use tap magic when thread cutting on the lathe, works a treat . Better than anything else I have tried anyway . I also use RP7 sometimes . Mike

Hi Ben,
I am in the same situation as you where I am not using my machines constantly and I often only use them for small jobs. I would be constantly worried about rust if I used a water based coolant.
I use Trefolex or Rocol RTD for hand tapping. I use the RTD for drilling or threading steel on the lathe. For most other jobs on the Lathe or Mill I use a mixture of motor oil and diesel oil. The mixture works well for drilling or machining aluminium. I don't need to work my machines too hard so I don't think fire is a problem. I always have some pieces of cardboard on hand to contain any oil spray. I usually apply the oil mix with a small piece of drinking straw. Ignorance is bliss.
Russell

mixture of motor oil and diesel oil.

.

Interesting. I have leftovers of various grades of motor oil lying around. When the labels peel off its hard to know what grade it is.

Got plenty of the diesel stuff.

Will give it a go. Only issue I might have is how thick the concoction is.

Originally Posted by Ben Dono

An oil can would be better as it's mostly closed up but I prefer to use a small acid brush for adding cutting fluids.

I use quite a small pot.....actually, it's a 50ml plastic specimen jar with a magnet dropped in it so it does not topple over and it's stuck to the top of my drill press. I keep it under half full as it's the right height for the bristles. The magnet keeps the swarf out of the brush as well.
So at a guess, it's 8mls of turps, 12mls of cutting oil and about 5mls for the magnet. It's not a whole lot of fluid on hand. You are right, the turps will just evaporate off. My workshop is very drafty and pretty darn big. If I was in a basement with no ventilation I think I would be avoiding it to be honest.

Cleanup....well I guess you could call it messy. It's about the same as with any cutting fluid really. The cutting oil is water dispersable so parts just get a wipe with a dry cloth or a proper scrub if I'm painting them.

The turps evaporates off pretty fast once it's crept over the part due to heat and the increased surface area. What's left over is the cutting oil which keeps the rust down until I clean it up for paint.

But your right! A fire hazard is something not to be taken lightly. I'm always conscious of that as I weld and grind in here along with a lot of different flammable products around the shop.

I store my bulk fluids on the other end of the shop for that reason. I keep quite small bottles on hand this end for daily use. Actually, I try and keep the workshop tidy.... It feels a bit safer and I'm less likely to knock things over!

I'm going to keep this mix for the drill press only as it appears to flow to the cutting end much easier.
No one else appears to be using 'HillBilly' cutting fluid mixes....I'm going to take that as a silent hint fellas and look for a better option!

You could always make a spill resistant container like the one Mr.Pete 222 featured on one of his recent videos,https://www.youtube.com/watch?v=HOAK4-Kd7QA not much fuel would be available and easy to smother any fire if you were unlucky enough to have one start.
If you are only going to use this mix on the drill press, then water based coolant/lubes should not be much of a problem. Just wipe down with paper towel after job done, and for tooling or sensitive workpieces a couple of drops of Lanotec or similar spread thinly by hand works well for me. I even have metho in a spray-pack which I sometimes use to de-water rust prone items from time to time, - Just spray on wet areas, and wipe off with clean rag or paper towel, followed by Lanotec if appropriate.
Rob.

Originally Posted by Ben Dono

Funny you should mention that Bob, it passed my mind as well and I cannot say I conducted any test on it other than drilling a lot of holes.. The drill ended up burning me when I pulled it out so it was on the hotter side of how I usually end up working..
I have read a few articles on people using kero mixed with waste motor oil as a cutting fluid. It's a guess but I think kero has a higher flash point than turps but it was on my list to look up. I was not keen on using waste motor oil as I have read you have no real control over what additives have found their way into it.
Again, it's a wild guess but the small amount of smoke from proper cutting oil and turps would be less noxious than a small amount of smoke from an unknown waste motor oil and turps.

And for god sakes Bob, don't brink up the bloody dust extraction thing again mate!

Just in case that last line gets misunderstood, It was honestly a light hearted joke Bob! Have a chuckle with me on that one!

Thanks for the comment about it being as thin as you can get it! I'm surprised i did not take a closer look at it before. The thinner oil is proving much better.

Any thoughts on it being more flammable Bob?
I can't say I have ever read of anyone setting a lathe or mill on fire before.
I can tell you that if I'm the first, I will take some pics and post them up here with a red face!

you know i was turning steel not to long ago. Using spay penitrene as a coolant. Mainly because it was convenient. A fair bit of the penitrene was getting flung around. After a while penitrene soaked swarf
blocked the tunnel from the bed to the chip tray. Some hot chips then started a small fire .Under the chuck.
So i stopped and cleaned up vowing to reverse a few bad habits ive picked up.
aaron