# My observations on machining copper---



## Brian Rupnow (Aug 10, 2008)

For the latest steam engine I am building, I needed a nice thick baseplate. I had a large peice of 3/4" copper left over from an automated welding cell, so decided to use it.---Now don't get me wrong---I had been warned by others on this board how nasty it was, before I even started. however, free is free, so I decided to go with it. Firstly, copper is much heavier than brass or aluminum, even slightly heavier than steel. It does cut okay on the bandsaw where I cut my aluminum. When you are machining it, it does not machine cleanly---rather it smears!!! If you are cleaning up the face with the end of a a rotary end mill, it will push a "bow wave" of uncut material ahead of the cutter, then grab, briefly try to stall the machine, then shear off, and keep repeating that action. cutting fluid helps a bit, but not a whole lot. Along machined edges, copper pulls up an incredible burr, that has to be filed off later. It seems to saw, drill, and tap okay, but is kind of a miserable pig to machine on a mill. This is the first time I have tried to machine copper, and I probably won't use it again, but I thought I would share my experience with you fellows.---Brian


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## Bogstandard (Aug 10, 2008)

Brian,

Try a bit of full cream cows milk as the lubricant, it seems that copper needs natural fatty oils to cut with any decency.

The correct thing to use is tallow, but because of the time of year, they are difficult to catch. Their legs fall of in the spring, so they cannot land, and they don't grow back until the autumn.

John


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## Lew Hartswick (Aug 10, 2008)

Bogstandard  said:
			
		

> The correct thing to use is tallow, but because of the time of year, they are difficult to catch. Their legs fall of in the spring, so they cannot land, and they don't grow back until the autumn.
> 
> John


Is this a Brit joke? I don't get it.
Pse. explain.
  ...lew...


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## Bogstandard (Aug 10, 2008)

Lew,

Sorry if my sense of humour is a bit over the top. Typical silly Brit humour.

Tallow is in fact the correct material to use, but is rather difficult to obtain nowadays.
I has been highly refined and used by electricians for cutting threads on conduit.

John


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## Mcgyver (Aug 10, 2008)

that's such a nice big hunk of copper and copper is so dear i wouldn't use it for anything but something that has to be copper....pick up a hunk of steel and tuck the copper away and one day you'll be glad you did. I've heard of using milk and such for machining copper, you're a brave man to try it, can't image what the shop would smell like in few days.


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## Metal Mickey (Aug 10, 2008)

It is well known that tallow is the staple food for Haggis. It only grows at a 45 degree angle to the ground which is why it is found in Scotland and always on hillsides of 45 degree or more. Haggis have their left legs (front and back!) longer than their right to enable a safe walk around hillsides.

In the depths of winter haggis searchers follow the haggis tracks in the snow. When they find them the Tallow is taken out of a velvet bag (red is best) and the lead the Haggis in the opposite direction. Gravity then takes over and they fall over and over down the hill where the Haggis gatherers pick up the dizzy dopes and put them into sacks ready to be hung ready for Burns night and all haggis hunters tack a sip of whisky and cry out.....


"Some hae meat and canna eat,
And some would eat that want it,
But we hae meat, and we can eat,
Sae let the Lord be thankit."​
I am trying to get a picture of the hunt but they are very secretive about locations........I will try though for our cousins over the water........


I found a picture of a hunt I was privalged to be allowed on about 8 years ago. I can't reveal the location but it was taken about 0300 hours.......








Best regards, and good luck for a tallow hunt but leave some for the Haggis hunters eh............


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## rake60 (Aug 10, 2008)

Cutting copper isn't all that complicated.
It does require very sharp, positive rake tooling!

I still remember the very first time I cut copper.

It was a 48" OD ring that was to be machined to become a communicator 
ring for a large electric motor. I used a standard right hand turning tool with
a .030" nose radius carbide insert in it.
Three seconds into the first cut a glob of material loaded up on the insert and the 
ring was ripped loose from the jaws. After slapping the E-Stop and checking my
pants to see if a change was in order, I replaced the insert with a sharp
positive rake tool. That actually cut the copper instead of trying to push the
material off as you would with steel.

Rick


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## David Morrow (Sep 10, 2008)

I have only cut copper on my little Sherline CNC mill. I used a small, very sharp end mill, speed set at 10,000 RPM, and set the feed at about 2 inches per minute. Make haste slowly. Time isn't an issue so I just went upstairs and watched a movie while it cut. I was cutting a plaque for my mum's final resting spot so it was important to do it right. It was about 4"x6"x.150" or so. I was very pleased with the result. I'm sure Mum is too.


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## Kludge (Sep 10, 2008)

Re: Haggis & Tallow ... 

Am I the only one who gets and enjoys Brit humor?

Kludge


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## baldrocker (Sep 10, 2008)

Kludge
There is nothing funny aboot haggis.
Despite being an extremely vicious creature
something akin to the Tasmanian Devil but ball shaped
they have been declared an ENDANGERED species by
the gnomes of Brussels
Typed with one hand
Baldrocker


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## Kludge (Sep 10, 2008)

baldrocker  said:
			
		

> There is nothing funny aboot haggis.



No, but the mention of red tallow was. We all know it requires a sober Irishman and orange tallow. 



> Despite being an extremely vicious creature something akin to the Tasmanian Devil but ball shaped



foot or rugby?



> they have been declared an ENDANGERED species by the gnomes of Brussels



What do those Brusselians know anyway? All they're really good at is getting into chocolate fights with the Dutch and French.



> Typed with one hand



I dare not ask what the other was doing.

Best regards,

Kludge


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## baldrocker (Sep 10, 2008)

Kludge
See my post in safety forum.
BR


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## Kludge (Sep 10, 2008)

baldrocker  said:
			
		

> See my post in safety forum.



See my replay, same place.

BEst regards,

Kludge


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## ianjkirby (Sep 11, 2008)

Kludge said;


> We all know it requires a sober Irishman



Haha! If anyone can find me a sober Irishman, I will give them all the tallow they want, of any colour, wrapped in haggis, and delivered by a Tasmanian devil.  
Regards, Ian.


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## Kludge (Sep 11, 2008)

ianjkirby  said:
			
		

> Haha! If anyone can find me a sober Irishman, I will give them all the tallow they want, of any colour, wrapped in haggis, and delivered by a Tasmanian devil.



Your tallow is quite safe. 

By the way, I guess you know that historically the English left the Scots alone during a haggis hunt. They invariably wound up in the wrong place which meant the haggis saw them and charged. The results were too horrible to describe. 

BEst regards,

Kludge


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## spuddevans (Sep 11, 2008)

ianjkirby  said:
			
		

> Haha! If anyone can find me a sober Irishman, I will give them all the tallow they want, of any colour, wrapped in haggis, and delivered by a Tasmanian devil.



Well, I dont know if I count, I'm sober, I was born and reared ( and fronted ;D ;D ) in Ireland (although of english parents :-\ ), and I'm sober, in fact I cant stand the stuff at all.


Tim


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## Bogstandard (Sep 11, 2008)

After all the silly Brit humour I will explain.

The correct lubrication for cutting copper is tallow.

http://en.wikipedia.org/wiki/Tallow

I think a name in the US would be a sort of Shortening, a fat used in cooking.

http://en.wikipedia.org/wiki/Shortening

Tallow, in a refined version is used by electricians for assisting them in cutting and threading steel conduit tubes.

http://www.tooled-up.com/MicroCategory.asp?MAN=Plumbers-Tallow&CID=9&SCID=556&MCID=2478

If this is not available, full cream cows milk does a reasonable job in stopping it grabbing.

All this was said before, but it seemed no-one believed it.

John


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## Kludge (Sep 11, 2008)

Bogstandard  said:
			
		

> All this was said before, but it seemed no-one believed it.



It was read and believed. The humor came in when you said about the tallows' legs falling off in the Spring. Everyone knows it's in the late Summer. 

Lard, which is the fat used in cooking in the US, is a whole different kettle of cholesterol. I don't know if it can be used like tallow but I guess it could be tried. Some homemade soaps use tallow, though, so that's a potential "emergency source."

Best regards,

Kludge


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## BillH (Dec 19, 2008)

No idea what Tallow or Haggis are?


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## Kermit (Dec 19, 2008)

Beef tallow is a whitish (beef tallow) or whitish to yellow (edible beef tallow) substance. It is solid at 20°C and gives off a mild odour. It is not water-soluble, but it is soluble in organic solvents. The main components in both fats are: oleic, palmitic, stearic, palmitoleic, linoleic and myristic acid. Other fatty acids account for <1% of the product.


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## shred (Dec 21, 2008)

FWIW, some generic foamy spray 'cutting oil, good for ferrous and non-ferrous' did ok for simple punching of an off-center hole in some copper pipe with a 1/4" end mill, but even then you could tell it wasn't very happy about the whole affair.


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## Maryak (Dec 22, 2008)

Maybe there is an animal fat storage facility near you. Go and ask if they have some tallowQA samples, about 1/2 lb plastic jars. All they do is throw them out after they are sure the QA is OK. (That's how I got my tallow).

Best Regards
Bob


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## compound driver 2 (Dec 22, 2008)

Just use milk its easy and works


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## deverett (Dec 22, 2008)

Kermit  said:
			
		

> Beef tallow is a whitish (beef tallow) or whitish to yellow (edible beef tallow) substance.



When I was an apprentice cadet at sea, many years ago, we used to carry latex from Malaya (as it was called in those days) to Australia in deep (bulk) tanks. The tanks were lined with tallow to prevent the latex sticking to the steel and it was the cadets' job to line the tanks with the stuff and to clean out the tanks after the discharge.

It was a filthy, smelly job.

We also used to carry tallow in bulk in the other direction up as far as India. It had to be heated by steam coils in the tanks to keep it liquid. The stench was unbelievable when the tanks were opened up after discharge and we went down to clean the tanks.

Dave
The Emerald Isle


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## deverett (Dec 22, 2008)

Metal Mickey  said:
			
		

> It is well known that tallow is the staple food for Haggis.



It is a fact that Scotch Eggs hatch out into Haggis.

Dave
The Emerald Isle


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## Kludge (Dec 22, 2008)

steamdave  said:
			
		

> It is a fact that Scotch Eggs hatch out into Haggis.


Huh, for real? I've always wondered about how Scots were born. :big: :big: :big:

Best regards,

Kludge (Part Scot)


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## compound driver 2 (Dec 22, 2008)

Penny to a pound most of the problems you guys are getting with copper can be put down to the wrong rake angle on tools and the wrong angle on drill bits. Copper will cut just fine of you use the correct tools for the job. Tallow or milk helps but wont cure poor tool choice.


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