tapping oils..

[srmaietta]

Hey there.. In the flammable stuff cabinet in my shop I found a few gallons each of "Dark cutting oil" and "light cutting oil". Whats the difference? I've been using the dark as a general purpose cutting/tapping lube but of course Id like to know the diff between the two.

anyone?

thanks
~Steve

[HuFlungDung]

One of them is for 'lights out machining', while the other can be safely used in the daylight

Seriously, I think it has to do with the amount of the sulfer compound additive. The dark stuff is what I've always used when tapping steels of any type. Seems to promote tap life somehow, I guess it prevents that 'chip welding' phenomena that wants to break off the sharp tips of the tap teeth. This effect then produces cleaner looking threads. I think the guys who run pipe threaders all use the dark stuff, too.

[srmaietta]

Thanks, HuFlung..

we threw out a ton of the stuff but I kept a gallon of each for general use.. It should last me a while and then I can get something more specific if I need.

Makes sense about the pipe threading guys using the dark stuff because alot of the jugs of the dark were Ridgid branded.

~Steve