View Full Version : Fumes from cutting oil?

08-28-2006, 12:40 AM

I have been a lurker for quite a while and recently signed up. I am a newbie and have been machining occasionally for about 3 years on a mini lathe and mill.

Today I was machining a small steel shaft and the cutting oil I was using was putting off fumes. I am wondering what you guys do to avoid breathing that stuff? Or, do I need to use some other oil? I usually use whatever light oil is around as a coolant.



08-28-2006, 01:45 AM

In larger shops, there is enough space that the fumes dissipate without much problem. In the home shop, it can be more problematic. I usually set up a small fan near my machines if I anticipate a smoke-generating procedure. That still won't help if your entire room fills up.

Some oils are better than others, but if you're running your tooling at recommended surface speeds, smoke is pretty common. If you're using HSS tooling, try reducing your cutting speed. That will lower your cutting temperatures and may reduce smoking. If you're using carbide, you can probably get away without using oil.


08-28-2006, 01:52 AM
I wonder if hash oil would make a good cutting lube? :cool::D

08-28-2006, 02:01 AM
I wonder if hash oil would make a good cutting lube? :cool::D

Only for a little while....and then you would probably forget what you were working on.;)

08-28-2006, 02:04 AM
you might have to thin it with bong water.

A.K. Boomer
08-28-2006, 04:16 AM
I actually have to get a fix of cutting oil now and then , and it has to be high in sulfer to,,,, i'll tell you what i cant stand , delrin, i dont get headaches but i get them if i machine delrin, i hate delrin , i think its toxic.

Forrest Addy
08-28-2006, 05:00 AM
Cutting oil smoke was a common but petty hazard of the old time machine shops. In the home shop where smokes and stinks can find its way to monre sensitive and intolerant noses it's not uncommon to rig a small exhaust blower to suck up the fumes and vent them to the great out doors.

Smoke avoidance isn't that hard. Machine dry in all materials and cuts except those which require a little oil for finishing.

08-28-2006, 07:55 AM
That damn sulfur based oil was great for cutting but that is partially to blame for my right lung barely operating. Probably get the other one someday. It was damn good lube though; don't breathe these oil fumes any more than necessary.

08-28-2006, 08:36 AM
Use an exhaust fan to remove the oil from the shop, a shop vac or small fan can be used to remove it from the immediate area.

If you are using any oil for coolant, you will get little benefit. There are water soluble coolants available that do not fume as badly as mineral oils, and the old standby sulfur based medium or dark cutting oil, which will fume. WD40 or alcohol are good coolants if you are machining aluminum.

08-28-2006, 08:49 AM
I have found that "Buttercut" cutting and tapping compound made by Crown gives off minimal fumes compared to most of the others I have used. It says it contains "non-edible animal fat". Lard?

On the other hand I don't use it very much - only for parting off, and the final pass if I want a good finish as Forrest mentioned.



08-28-2006, 10:08 AM
I've got a small box fan (out of a computer) rigged up above the end of my lathe. When I'm doing something that involves smoking cutting oil, I turn that on to dissipate the fumes. My basement, overall, is of pretty good size so I find that's usually enough. In general though I follow Forrest's suggestion: I try to avoid generating smoke as much as I can.

08-28-2006, 12:07 PM
Use bacon grease. Non-toxic, non-ozone depleting, and it's multi-tasking.

Everybody in the neighborhood will be over to see what you're making.

08-28-2006, 01:45 PM
Try a fan.

08-29-2006, 10:01 AM
Thanks for the advise everyone. Once we are finished moving, I'll rig up an exhaust fan.


09-03-2006, 11:41 PM
Happened to dig this up today and i was wondering about the smoke caused by used motor oil...it seems to hang around for awhile even with the garage door wide open. I don't suppose thats very good for one's lungs. What have you guys heard/ know about it? (as a cutting oil) I run dry most of the time now unless its a finish cut. I figure the extra money on tooling is better than having some lung cancer or something when i'm 40... :D

I like the idea of bacon grease...

Optics Curmudgeon
09-04-2006, 01:13 AM
One of my early employers was a fellow that had lung problems. Although the shop was relatively small it had the cleanest air of any shop of any size I ever worked in. He had filters, ventilators and electrostatic cleaners and there was no smoke, dust or anything in there. Probably boosted his heating bill a bit, though.


09-04-2006, 01:41 AM
Using used motor oil as a cutting lube is a bad idea, especially if it smokes. It has all sorts of nasties in it including acids and a variety of metals. Not only does it contain iron but will have some traces of lead from some of the steel parts as well as very likely some hexavalent chromium which is a strong carcinogen. It may have some cadmium from babbit as well as nickel and a bunch of carcinogenic pyrolitic hydrocarbons not to mention significant amounts of MMT (methylcyclopentadienyl manganese tricarbonyl). Bad plan.

09-04-2006, 01:51 AM
Kinda what i figured but it would've been a nice economical solution to cutting oil woes so i thought i'd see what you all had to say on the matter :)

09-05-2006, 01:36 PM
My wife popped in my shop last evening to nicely inform me that I was stinking up the upstairs. I was doing some milling and used some sulfur based pipe threading fluid. I picked this stuff up at a significant discount at a local hardware store that was closing - it works great but even with a fan makes one heck of a stink. I use something called Tapzol that's not too bad but still stinks. Some of the sulfur free, animal fat based products work really well and while not entirely odor free - the odor is minimal and far less noticable.