Machining copper stock.

[mtaylor]

Just a quick question as I got mixed answers from the place I'll be buying some copper rod to make kettles for my ship's stove.  When turning on a lathe or drilling/machining, should I use cutting oil?  Or not use anything?  I've done brass without oil, I've never done copper.

Edited April 19, 2018 by mtaylor

[Burroak]

Mark I typed turning copper on a lathe in YouTube and watched a couple of videos of turning copper and the operator didn't use cutting oil or coolant. 

[KeithAug]

Mark - copper can be quite tricky - it work hardens quite quickly and pick up on the tips of tools can give a poor finish. Because it is very soft it can also be prone to snatching at the tool. My advice would be to use HSS tools which are sharpened to good edge. My preference is to use cutting oil as i think it lessens the tendency for pick up and snatching - as a result gives a better  finish.

 

But here is what the experts say:-

Edited April 19, 2018 by KeithAug

[mtaylor]

Thanks Keith. I picked up the copper today and hope to start this weekend. All my cutters for the lathe are HSS.   I do have some cutting oil.  I wonder what "lard oil" is?  Lard?

 

I may give it shot without oil based on what Greg said.   

 

 

Edited April 20, 2018 by mtaylor

[kurtvd19]

I read someplace that Bacon fat could be used as a lubricant for working on non-ferrous metals.  As I had just cooked a pound of Bacon I had a jar of fat cooling off.  Took a very small bottle lid of it to the shop and it worked quite well when I was drilling with a #74 bit pretty deep.  I was concerned about the depth w/o lubricant and the Bacon fat worked quite well - didn't break a drill bit and got 6 holes done.  A toothpick dipped into the fat transferred the fat to the drill bit.

Kurt

[grsjax]

Two things.  First, what type of copper are you turning?  There are many grades and alloys of copper and they have different properties. 

Second, if you use lard or bacon fat be sure to clean it up really well.  When it starts to go rancid it can really stink up a place.

[mtaylor]

Interesting idea.. bacon fat. Maybe I'll have to have bacon tomorrow morning. 

 

I'm not sure what grade this copper is.  I bought it at the local metal yard (1 foot long by 3/8" for $3) which was the smallest diameter they had.

Edited April 20, 2018 by mtaylor

[KeithAug]

M

7 hours ago, mtaylor said:

I wonder what "lard oil" is?  Lard?

Mark, lard is animal fat 

 

Lard oil is the clear, colourless oil pressed from pure lard after it has been crystallized, or grained, at 7° C (45° F). It is used as a lubricant, in cutting oils, and in soap manufacture. ... Lard oil has excellent lubricating qualities, but it tends to become rancid

Edited April 20, 2018 by KeithAug

[Jim Rogers]

Lard is what my Mom called bacon fat.

[KeithAug]

Mark - I'll be interested to how you get on with copper. 

[mtaylor]

9 hours ago, Jim Rogers said:

Lard is what my Mom called bacon fat.

That's what I thought... though it could be beef (from hamburger, etc.).  Now I know.   As far as cleanup.... there various solvents including dish soap.  I note that lard can be bought at the local grocers.   I'll try the cutting oil first.

4 hours ago, KeithAug said:

Mark - I'll be interested to how you get on with copper. 

I'll let you know here as I want to test a couple of lubes and see what works and what doesn't work.

[clifforddward]

More important perhaps that cutting fluid is the need for tools to be absolutely sharp!

 

Rake angle can also be a factor...less is better but only if the tool is dead sharp.

 

And small cuts....

[Jack12477]

Lard - I remember as a kid my Mom collected ALL the meat fat in empty metal coffee cans then put them once a week on the front porch stoop for some guy in a truck to collect the "lard" so they could make soap, lard, grease, and other things for the war effort - that's WW II - yes, I am that old.

[Jaager]

The fat from the beef is tallow.

Allergic to beef,  I discovered that some Mickey D add it to

the vegetable oil to flavor FF.  Never would have had a reason

to know about it otherwise.  I seem to recall from a school trip

to Colonial Williamsburg it was used for candles, but did not bother to 

know what it was.

 

Since you are likely to be inside your home and not

a dirt floor shed, you may wish to forego the animal fat and

try Mineral Oil from your pharmacy.  The spinning may spray

and a rancid streak on the wall behind your bench or ceiling

above may not be easily seen but still provide an unpleasant odor.

Sears used to sell quarts of light machine oil, can't find it now, so

I use MO instead.

 

[lmagna]

Tallow historically was more commonly used as a lubricant for steam engines than it probably was for candles. It was one of the few lubricants that handled the steam and heat well.

 

Lou

[wefalck]

To be honest, I never use any cutting fluids for turning model parts on the lathe. As pointed out by others, sharp tools are essential to avoid work-hardening. If any material starts to build up on the cutting edge, stop and remove the material or you may ruin your surfaces. Otherwise, I would not be too concerned about working with copper. You may have to try to optimise work-parameters for your special case, so be prepared that the first part may not turn out as desired.

[mtaylor]

On 4/27/2018 at 3:17 AM, wefalck said:

You may have to try to optimise work-parameters for your special case, so be prepared that the first part may not turn out as desired.

That seems to be my normal mode of operation.  Test, test, test, and maybe I get what I want.  If not, change parameters and try again.

[Gaetan Bordeleau]

When turning small jobs, small diameters I never use cutting fluids.

For milling, I always use cutting fluid, mainly to preserve the cutters life and over heating both the part and the cutter.

For drilling, especially deep holes, I always use cutting fluids for the same reasons. Also it is much easier to do the job with fluids.

 

In the old time, they were using all kinds of grease and fluids. These old tables that we see were made for LARGE parts turning not really for Hobby jobs.

Today, it is a lot easier, Only one solution for every thing. It look like oil, we add water to it and it turns white just like milk.I also tried other kind which turned blue.

 

For small diameters, it is not really necessary. The most difficult part I turned is a 2 inches rod of copper. Cutting fluid was a necessity to keep the part cool.I guess that if we put the part in the cooler it would help to begin the turning.

If nothing is use copper will become hot  and sticky very fast and it will be difficult to make clean cuts but this is for large diameters only.

 

[Bob Cleek]

When working to close tolerances, I'd hesitate to put a work piece in the freezer to "cool it down" before turning. Temperature dictates the size of the work piece.  When a "frozen" work piece warms back up, it will be larger than when it was cold.

 

A tool cutting a larger diameter work piece will heat up much faster than when reducing their respective diameters by the same amount because the tool has to remove a lot more material to turn a quarter inch off of a two inch diameter rod than off of a one inch diameter rod. When size matters, you can never have too much lubricant.

  

 

[jud]

Bacon Fat is Bacon Fat, not Lard, I save it for flavor when cooking. Lard is rendered from raw pork fat, not cured like bacon or Ham. Lard is rendered from the trimmings over low heat until a liquid, then filtered through layers of cheese cloth into storage container and allowed to cool and solidify, it will be white when set up. Straining the fat through cheese cloth removes any solids that will cause the Lard to go rancid and can be kept in a cool place for a very long time before use, it will be free of any salts, sugars and peppers used in curing meat.

jud

[wefalck]

A would go with Gaetan: I rarely, if ever, use any lubricant on my lathes - there are not set up for using coolants anyway. Yes, pieces and tools become warm sometimes, but if they get so hot that the workpiece or tool gets damaged, you are doing something wrong, i.e. perhaps the tool is blunt. In the model workshop one rarely takes off so much metal that heat generation is a problem.

 

There are some materials, copper may be one of them, that tend to stick on the top-edge of the cutting tool. In this case a bit of lubricant might help. Or a steeper top-rake of the tool.

 

When milling with a multi-tooth cutter, the situation is different. There you need a lubricant, at least for steel, and particularly when milling or sawing slots, as the mill or saw might get jammed otherwise in the slot. A blast with WD40 or similar also clears out chips.

 

The same applies to drilling: oil for steel and sometimes aluminium, when holes are deep; nothing for brass; copper may need a drop of oil.

 

I only have sewing-machine oil and WD40 (or similar) in my workshop. I don't mess around with the animal fats that old-time machinist used.

 

[Wacom]

Having turned copper I have found the most effective way to get a good clean cut leaving a nice finish is with Kroil used by gun gun users and as an anti seize medium.

[thibaultron]

On the stripe of oil on the wall behind the lathe. I bought a large piece of formica and leaned it behind my lathe, resting the bottom inside the chip pan.  This kept the residue from the wall. Eventually a little got on the ceiling but that was over a few years.

 

I use cutting oil for all my machining. There are various types for different metals, but the regular ones for steel work, if that is all you have. I never turned copper, so I do not know if there is s specific one for it.

[mnl]

Lard oil is pressed from lard. It has been the go to cutting fluid for copper for years beyond count. It sets up just below room temp so when the shop is cold in the winter it has to be warmed to liquify it. It will also get rancid, so keep cold when not in use. There are other fluids that work almost as well for copper, just don’t use anything with sulfur in it. It will turn everything black.