Threads on copper rod

[PeterSibley]

I've been running threads on 5/8" copper rod , using a Whitworth die nut and holder and I'm not happy with the results.Some sections of the thread are tearing out.Should I be using a particular lubicant...I've been using very light oil and its not very effective.Any suggestions ?

[Nicholas Carey]

YOu should be using cutting oil (http://www.wurth.com.au/catalogueview.asp?pdf=M02_0911.pdf) (PDF).

It's specifically designed to cool and lubricate taps and dies when cutting thread. Tell the supplier it's intended for hand-cut thread (as opposed to machine-cut).

Use lots.

[PeterSibley]

Thank you Nicholas...will do .

[Allen Foote]

would it make a difference, with copper being so soft, if you are tapping course threads -VS- fine threads?

[Gary E]

Peter,

You say you are using a "die nut"... if this is what looks like a nut, it may be what we in the US call a re-threading die, they are ment to clean up allready threaded areas, not to cut new threads from the solid bar.

If this is what it is, I sugest a better Die, and yes, use some cutting oil, not lubricating oil.

G

[Leon m]

Yep,deffinately use course thread for copper,
a good cutting oil,and as Gary said make sure
it is an actual die and not a "thread chaser".

[Ian Wright]

Originally posted by Gary E:
Peter,

You say you are using a "die nut"... if this is what looks like a nut, it may be what we in the US call a re-threading die, they are ment to clean up allready threaded areas, not to cut new threads from the solid bar.

If this is what it is, I sugest a better Die, and yes, use some cutting oil, not lubricating oil.

GWhat Gary said, you need a proper die, not a die nut and the correct lube imo is red cutting GREASE. Reverse the direction ie back up every turn or less. Pure copper is very soft, what's the application?

IanW

[PeterSibley]

Ian,
bolting together the backbone of my boat,and before you say it copper is normal usage here in Australia, the normal sizes in a 45'fishing boat would be 5/8" in the backbone ,1/2" elsewhere. Just getting in early smile.gif Bolt lengths around 14".
The set I have is an old American tap and die set ....1/4" to 7/8", old but still sharp .It works beautifully on mild steel, its just the copper that is a problem. Thanks for the suggestions.
So which is it :
Red cutting grease
or
Cutting oil ?

[Andrew Craig-Bennett]

In Britain copper bolts would also be used for the backbone but they would usually be clenched on rings, rather than threaded and set up with nuts. The clenching process draws the bolt up a bit, just like it does with copper nails and roves.

[Gary E]

Peter,

If you can get to a machine shop, they would probably have cutting oil, sulphurized if you have a choise. I would prefer the oil over a grease because the chips will cling to the grease and clog up the die. Oil will allow the chips to fall away.

G

[PeterSibley]

Andrew, I'm not confident of my ability to sufficiently peen a 5/8" rod in some of the places I have to work.The thread works well.I had fifty or so gun metal nuts cast at my nearest foundry, I'm boring and tapping them to either 5/8" or 1/2" as required .

Gary, I visited a machinist friend today and "borrowed" a jar of cutting oil and also a sample of graphite grease.....I'll try both tomorrow.I agree with you regarding the free fall of chips, the copper is gummy enough already !

Thanks to everyone for their advice.

[Andrew Craig-Bennett]

Peter I think you have a very good solution - almost certainly better than peening the ends. I was just commenting that the use of copper bar in this situation is orthodox - it goes back to before Nelson's time - there are miles of thick copper bar in HMS Victory!

[PeterSibley]

Cutting oil !! Very nice thank you ,clean threads , very little galling.It's lathe cutting oil ,not the proper stuff but it works just fine !
Thanks all smile.gif

[mic]

Hi guys, sorry to bring this one back again but i'm just about to do what Peter has done. I've just gone and bought some copper rod, 1/2",3/8" and 5/8" and some corosponding hexagonal bar to make nuts out of. Now i'm a wood butcher and this is the first time i'm going to make my own bolts, i keep hearing this word peening, what does this mean?

[Ken Hutchins]

Peening is a hammering process, done with a peening hammer, the most common of which is the ball peen hammer. It is best accomplished with many lighter hits of the hammer. It's most common use is for peening the ends of rivets to change the shape from cylinder of the body of the rivet to the desired head shape which locks the rivet in place.

[mic]

Ahhhh, now i understand. I was thinking of threading both sides of the rod, one side just enough to get a nut on with the thread sticking out perhaps 1/2" and then smacking the top of the rod down on the nut, ya reckon this is gonna be good enough? It'd be a pain in the ass to have to peen 70-100 bolts :eek:

[PeterSibley]

Well thats what I do...a short thread one end, as you say about 1/2", then a longer one at the other to give a bit of slack to draw things up and allow for my mismeasurements ! smile.gif

[formerlyknownasprince]

Sorry, I missed this earlier, but there is no need to peen the bolts, which is what we did last time we made some bolts. We used a cheap flaring tool, held in a Triton Superjaws and peened them all by hand. This time we made up a device out of steel and simply pressed them

http://www.imagestation.com/picture/sraid101/p6a4a969b0ba8eaba9a9529ca6aab44d7/f9d62018.jpg

We made 28 of these then turned the threads on a lathe. Piece of cake. The only issues we had were the bending of the bolts, so we made a sleeve to go over the bolt shank while they were being pressed and a slight thickening of the bolt near the head - only from about 12.5mm (ie 1/2 inch) to 13mm which didn't cause any major problems for us and is easily fixed if needed.

I wrote this up about a month back - under "Making copper bolts"

Ian

Ian