Oil or water soluable?

[BigDave]

What is eveyone's opinion on water soluable oil or straight oil for a lathe and mill?

Both use flood coolant, but I hear water soluable can damage a sump pump and eventually get funky although rumour has it that synethic water soluable won't allow bacterial formation.

Opinions?

[C. Tate]

I have used both in my machining centers and I prefer the synthetic because it is cleaner. I machine almost any kind of material you can think of and do not have any problems with performance. You will probably not see any appreciable difference for one material to the next unless you are running very high production. There are as many opinions on coolants as there are manufacturers.
Synthetics do get "funky" mainly from bacteria feeding on tramp oils off of the ways. I have never heard of any coolants causing damage to pumps when mixed correctly. I have seen the synthetics remove paint from the machines because of the their high alkalinity. The soluable oils however can clog lines after long exposure. The synthetics tend to reject tramp oils better allowing for easy skimming.

The ultimate coolant is straight cutting oil the screw machine shops used untill the EPA made it to costly to dispose of. IMO try both and use the one you think is best. You may also try a mist cooler which is extremly effective on smaller machines like found in the home shop.

[BigDave]

Tate,

The problem with mist coolers is is smokes up the joint.

I remember working in shops that looked like downtown L.A. on a hot summer day it was so smoggy.

My mill uncharacteristically has a large sheet metal drip tray around the periphery as well as hoses from the tapped rear table holes to drain it all.

I like the idea of water soluable, since it seems a little less greasy and is easier to wipe off, but since both the lathe and the mill have internal sumnps and pumps, there doesn't seem to be an easy way to set up a dinky tramp oil skimmer, and it would require power anyway.

I see ads for sulfur and non-sulfur based regular oils, maybe I will go that route.

That is what we used to use our little Hardinge second operation turret lathes...man did I like that thing...I used to be able to run circles around the guys on regular lathes on 8 parts or more...

[Treven Baker]

I have some big machines I don't use very often and I don't want to put somthing in the coolant system that will go bad.I have lots of drain oil from various equipment- mostly engine some hydrolic. Would that work for cutting oil in the coolant system?
Thanks,
Treven

[SGW]

On mist cooling....

If the shop is getting fogged up, the mist is set WAY too high. I've got a Bijur FLuidFlex, and according to their way of thinking there should be NO visible mist. The cooling comes from the refrigeration effect of the coolant evaporating into the airstream, and the toolbit really gets cooled by the cold air. If there is any residual mist, it should be no more than can be evaporated by the heat of the toolbit.

You can really feel the cooling, too, if you stick your finger in the airstream and turn on the coolant. It should be adjusted so you just see a few tiny drops of liquid condensing on your fingernail.

Now, the current price of the FluidFlex is insanely high (my opinion, I'm sure Bijur disagrees!), but it works. I'm not sure how well the cheaper units work. The FluidFlex pressurizes the coolant tank, whereas the cheaper ones are suction feed, and you may not have the degree of control you need (or the quality of the nozzle may not be good enough) to have that balance of evaporation into the coolant stream but no visible mist.

If you think about buying a used FluidFlex, be really careful about corrosion. They use an aluminum pickup tube, and an alkaline coolant solution eats it up. It can also get furred up inside with crud, although that seems to be somewhat less of a problem with some brands of coolant than with others. I'm currently using KoolMist 77 or whatever it is, and that seems to work pretty well.

Happily, the whole thing comes apart pretty easily and you can clean it out without too much trouble, but I think Bijur made some poor choices of materials when they built it. At some point I may put in a stainless or plastic pickup tube and filter foot.

[C. Tate]

Have you thought about one of those chillers that use compressed air with no chemical I think one is called the Vortex (MSC). I have never used one but they are advertised to cool air 100 degrees below ambient temp. I have been told they work very well for turning and milling both. I think they run close to $300.

[bdarin]

You can easily make a vortex chiller for a lot les than $300. The only problem is, I can't remember where I saw the drawings, but metalwebnews.com might be a good place to start. They have gobs of projects and links to other sites, so it shouldn't take long to track it down. I'll keep trying to locate it. What it is is a small tube, compressed air comes in the side and vortexes internally. Super cold air comes out one end, and, since there is no free lunch, super hot air comes out the other.

[bdarin]

Found it....go to www.visi.com/~darus/hilsch (http://www.visi.com/~darus/hilsch) for a complete explanation, with drawings, of the vortex chiller.