Soluble oil really works

Are you using it as floodcoolant or in the mister?

I've tried the flood so far, and plan to try the mister. The mix I have may be a bit too thick for the mister, so I may need to dilute it a bit.

Joe Gwinn

Or it could be that you are running the tool too fast or perhaps you are attempting too much feed. Try backing off a bit and see if that improves your results.

Tried all that. Black sulfur oil worked well, Koolmist in water not quite as well.

Even when chattering, with the soluble oil, the chips were nice and shiney.

Cold-rolled steel machined easier than O1, and seemed happy enough with KoolMist. A2 was harder to machine than O1 -- no surprise there.

Anyway, I think I'm finding out why so much soluble oil is used.

Joe Gwinn

Yes!

Uh!? With what would you like to cool that's cooling better than water?

Do you say that you mix cooling fluid with extra oil? The soluble oil needs a mixture of about 1:10 .. 1:20. And no extra oil. You shouldn't mix that, because it ruins your cooling fluid.

You'll discover that you can have bigger feed, nicer surface, wash away the chips, have longer tool-live ... and need rubber boots. :-)

Nick

The comparison was with KoolMist 77 in water. Koolmist has no oil.

No it's 5% or 10% Rustlick WS-5050 in ordinary tap water. All the oil comes from the WS-5050. The label speaks of "chlorinated paraffin". I started out at about 10%, and the mix seemed a bit too thick, so I thinned it out with more tap water.

Anti-slip rubber boots. The blue color makes it easier to see where the stuff went. At least the oily layer will prevent rust.

I tried the soluble oil on a piece of A2. The 5/16" hole first rough drilled with a "H" stub drill (0.266") and then final drilled with a

5/16" two-flute endmill (slot drill) yielded a fairly smooth bore. I think the black sulfur oil was slightly better, but will have to do the comparison.

The surprise was the countersink, where the cut surface was conical but very rough. Under a 10x magnifier, one can see that the surface metal is torn perpendicular to the surface, looking like a dried and cracked mud flat. The two countersinks used show no signs of distress. Again, this will need to be tried with black sulfur oil, for the comparison.

Perhaps the problem is that A2 is difficult to countersink, or perhaps a different cutting fluid is needed.

Joe Gwinn

Couldn't find anything about KoolMist 77, except that it is semi-synthetic and soluble.

5% is really thick. :-) They suggest 10% .. 30% for that product.

If you don't make it too thin!

Cutting oil is good for cutting threads or reaming blind holes. If you can flood the work and wash away the chips, coolant works better in my experience.

Countersinking can be nasty. Most common error is a feed too slow. If you do the math with the suggested feed rate and RPM, the countersink will be finished in fractions of a second. Not so easy when doing manually. :-) So down with the RPM.

Nick

Yes, that's all they say about it.

My 10% is an eyeball estimate. It's still pretty thick.

Everything feels oily afterwards.

I've been experimenting with the spray mist, and it is not obvious that spray is less messy than flood cooling.

Hmm. My suspicion was that I was going too slowly. Time for some experiments. I bring the stationary countersink down into contact with the hole, zero the quill micrometer scale, raise the quill and start the bit spinning, turn on the spray, and go down to 0.050" deeper than the zero, watching the dial, not the countersink, so "a few seconds" isn't a problem.

Joe Gwinn

I'm not that convinced with spray mist. Albeit, I haven't tried it. It is right, that it is cooling very well, but also, it is not very good to your health. In an industrial environment, it is used in closed cabinets and the air gets filtered.

And then, it doesn't wash away chips.

Nick

I believe that. I turn the spray on last and turn it off first.

Well, with sufficient airflow, it blows them away. I've been doing that...and getting the spray everywhere.

It's easier to change cutting fluid with spray mist than flood. I'm not sure how important this really is.

Joe Gwinn

LOL! And the chips. :-)

Not that much to my experience. I'm using the same coolant for everything. Steel and alumin(i)um. It works for both, albeit there are special ones for Al.

And sometimes a drop or two of cutting oil.

Nick

Which coolant make and model are you using?

Meaning black sulfur oil?

Joe Gwinn

The pump? Selfmade container and a 350W or so clearwater pump for around $40. The soluble oil was CIMCool, and now it's from EUROLUBE. Local brands I think. The later sold my t&c grinder and I took 5l with me.

No, albeit I have a black cutting oil from Roytec, I prefer the "Jokisch" brand. The Roytec seems only to be good for thread cutting, the Jokisch (a "normal oil colored" oil) is thinner and better for work on the lathe and mill, like cutting or reaming. And it doesn't stink that much. :-)

Nick