Non-staining Cutting Fluid

I need some help choosing a cutting fluid for turning and milling.

When I use cutting fluid, I apply small amounts via a plastic drip bottle (my lubricating needs are for aluminum, cold rolled steel and drill rod/tool steel) and used primarily to lubricate. I have been using TapMagic with much satisfaction but have noticed as many others on the board have commented: if cuts are aggressive enough to cause smoking, the TapMagic causes machine discoloration (unless sessions are followed by exhaustive wipe downs with oily rags).

Can anyone recommend a good cutting fluid which will not stain my work or tools? I tried some Trico synthetic Microdrop lubricant from a small sample I have, and it seems to work very well, but the price knocked my socks off at $71/gallon.

(I also have an unused 15 year old MicroDrop unit, but it never seems to be worth while hooking it up, as the plastic drip bottle seems to serve my needs. Although I usually agree that the more tools the better, my innate feelings about cutting fluids is the less the better….I hate cleaning up, rust and discolored tools!)

I've searched the archive, but couldn't come up with a good consensus.

Thanks,

Mike

Try WD-40 (smokes but is very clean to work with) or plain old peanut oil (hardly smokes unless used sparsly). Lard is also a good cutting fluid but it congeals when cold and goes rancid in time. Almost any organic oil is an excellent cutting medium. Some are better than others. Most smoke when hot enough (above 450F).

I mostly cut dry so I can suck up the chips with a good shop vac. I have no desire to drench my surroundings with oil or water based coolant. When I need cutting aid as for tapping or threeading, I apply it with a brush.

Thank you, Forrest.

I am very confused about the concept of cutting dry. I realize that in my home shop I am not pushing my cutting tools, but I thought a cutting fluid was important to get a good fininsh and extend tool life. Would a stream of compressed air to blow the chips away be just as effective finish-wise? I guess you cut steel at a rate that keeps the chips at a temperatue below "blue?"

Mike

Generally speaking cutting fluids help finishes and exend the cutter life a trifle. In the home shop few materials are hard or difficult to machine. Most home shop milling problems arise when chips are re-cut (the milling cutter drags them through the cutting zone.) Since a milling machine has no similarity to a mulching mower and the re-cutting significantly shortens cutter life this is generally a "bad" scenario.

Yes a blast of air will help keep the cutting zone clear of generated chips. I prefer a shop vac in this instance to collect the chips rather than scatter them with compressed air and later sweep them up.

It's tempting for the newbie to want to run coolant; for one thing there is the run-with-the-big-dogs mistique about it and for the other it does work generally. Most home shop machine are poorly guarded or have effective splash containment - nor are they well equipped for mist/smoke/fume extraction or handling drippy masses of chips. This leads to unwonted mess and some safety hazard. Therefore, I generally counsel machining dry (with vaccuum chip pick-up) except for finish cuts where some cutting medium is indicated.