PDA

View Full Version : Quick copper pipe question...



Liger Zero
03-04-2009, 03:32 PM
I got a small project to make some widgets out of copper pipe. Used to work copper at Spinco years ago but I've forgotten a few things.

I remember that you have to soften it between operations, heat it up then quench it... more or less take the "ring" out of it and replace it with a "meh" sound. :D

That's for forming operations which I'll be doing... I know we used to turn the stuff as well but I don't recall if we turned it hard or soft.

I'm thinking hard as the collets or chuck-jaw would crush soft material.

...what I'm going to do is reduce the outside diameter on one end with a carbide tool , form an internal pocket inside the part with my home-made "reach tool" (bastardized boring-bar) then "spin form" (expand!) the other end.

Got everything in place I'm just trying to work out the sequence of operations, I want to minimize running the torch as much as possible.

10KPete
03-04-2009, 04:19 PM
Annealing: Heat to dull red then cool. You don't need to quench it unless you're in a hurry.

Machining: Use razor sharp HSS tool bits and a bit of kerosene. Carbide will just mush it all up. Machine it in the hard state.

To remove the heat scale, dip the parts in diluted muriatic acid like for swimming pools.

Pete

Liger Zero
03-04-2009, 04:30 PM
Annealing: Heat to dull red then cool. You don't need to quench it unless you're in a hurry.


Right, that much I remember. I'll be quenching it because I don't have room for a half-dozen red-hot copper widgets in my workshop. :D



Machining: Use razor sharp HSS tool bits and a bit of kerosene. Carbide will just mush it all up. Machine it in the hard state.


Ok, that I didn't know. I had planed to use carbide, I can get a HSS tool quickly though. The internal pocket tool I made is HSS so that much is ok.



To remove the heat scale, dip the parts in diluted muriatic acid like for swimming pools.
Pete

Didn't know that. :confused: Next time, I got a small quantity of nitric acid in a carboy on standby for this project.

I've always used nitric acid for cleaning copper. Quick 30-second dip in dilute acid, followed by high-pressure rinse, followed by a 30-second dip in boiling water. Absolutely beautiful copper-colored copper parts. We called it "Brite Dip" at Spinco, I was the operator on that line and the annealer. I'd split my time on both lines every day, sometimes I'd run formers or spinners if needed.

Great job, sad to see them in such decline though. :(

oddball racing
03-04-2009, 05:26 PM
I've always used nitric acid for cleaning copper. Quick 30-second dip in dilute acid, followed by high-pressure rinse, followed by a 30-second dip in boiling water. Absolutely beautiful copper-colored copper parts. :(
Where would one find some nitric acid wash for such purpose?

10KPete
03-04-2009, 06:15 PM
Didn't know that. :confused: Next time, I got a small quantity of nitric acid in a carboy on standby for this project.

I've always used nitric acid for cleaning copper. Quick 30-second dip in dilute acid, followed by high-pressure rinse, followed by a 30-second dip in boiling water. Absolutely beautiful copper-colored copper parts. We called it "Brite Dip" at Spinco, I was the operator on that line and the annealer. I'd split my time on both lines every day, sometimes I'd run formers or spinners if needed.

Great job, sad to see them in such decline though. :(

Well, if you have access to nitric that's even better!! I mentioned the muriatic 'cause it's so readily available for most folks. But nitric is the 'right' stuff if you can get it.

I thought that "Brite Dip" was the chromic solution that followed the nitric bath??? I could easily have those two confused!

Pete

Liger Zero
03-04-2009, 06:22 PM
We discontinued the chromic trioxide solution because its so god-damn dangerous. Still had the tank but no material on site and no intention of getting more. Stuff is nasty, not a case of "might" cause cancer it WILL cause cancer! The nitric acid wash/rinse and boiling water bath do the same thing at less cost and less enviromental and health/safety cost as well.

As for nitric, I have a friend who purchases for a chemical plant he ordered me a jug... I have a large carboy I can dilute it in... plus access to the proper safety gear. Special long rubber gloves, full face shield, splash apron... I'm no stranger to chemical safety. :)

As for disposal, same friend at chemical plant will take it off my hands and run it through their disposal process.

10KPete
03-04-2009, 06:49 PM
Yeah, I know about the chromium tri-oxide thing. We had to quit using it back in the late 70's. And that's OK 'cause like you say it's bad stuff.

I haven't had the need for a lot of nitric; what little copper cleaning I've needed to do in the last 20 years I've been able to do with Zud or Lime-A-Way or dilute muriatic. Disposal is sorta simple around here, what with the big boat yard, 'cause they have a way to deal with heavy metal wastes and don't mind a guy with a cup full of stuff!

I seem to do a lot of paint prep on aluminum outdrive boat housings. Use the regular Alum-A-Prep solution and the Alodine after that. 5 gallon bucket stuff.

Pete

Liger Zero
03-04-2009, 06:56 PM
There is alot of neat nature-stuff around here that I try to preserve as much as possible. If it costs me $25 to dispose of a jug of acid after a project so be it. Its worth it to me when the luna and cecropia moths gather around the porch light. :)

Bob Ford
03-04-2009, 08:42 PM
Did you know that copper nitrate the residue from cleaning copper with nitric acid is explosive when dry.

Bob

Evan
03-04-2009, 08:53 PM
Something that a lot of machinists don't know about any more is carbon steel tooling instead of high speed steel. Nothing takes and holds a sharper edge than high carbon steel except perhaps diamond. The reason it isn't used any more is that it cannot withstand even fairly mild heating or it will lose it's temper. That isn't an issue when turning copper because copper is such a good conductor of heat. Most types of high carbon steel can be used to make turning tools but it takes practice and experience to learn how to heat treat some of those steels. The easiest steels to use are the non alloyed carbon steels such as anything that has more than about 0.4 percent carbon. That includes right up to music wire which is close to 1 percent. These steels may be water quenched after heating and the temper drawn down in an ordinary kitchen oven or even with careful use of a propane torch.

You have to be careful when handling these tools because if properly sharpened thay are as sharp as a razor blade which are also made from high carbon steel.

Liger Zero
03-05-2009, 10:40 AM
Did you know that copper nitrate the residue from cleaning copper with nitric acid is explosive when dry.

Bob

Yes, and you can make thermite with a grinding wheel and some aluminum and iron scrap. :p