Peening copper rod

[glynn]

This is probably obvious to those of you who do it regularly, but...

I have to fix two sheets of bronze to a block of teak for my anchor fitting, and the plans call for 3/8ths copper rod peened over at both ends.
My questions are:

How much longer do I leave the rod before attacking it with a hammer, and
How do I keep everything tight while I beat the second end?

Thanks again in advance,

Glynn

[JimL]

This should be staight forward as long as you have some good G clamps and can hold all the parts very securely.
1. First anneal (heat to cherry red and cool or quench) your rod to make it workable when cold. You are basically following the noble art of riveting.
2. Allow no less than one and a half (1.5) times the thickness of the bronze plate for peening (riveting) over. More if you want to have a raised head. Countersink the holes before peening if you want the peened heads smoother or slightly flush, you do need some raised head for strength.
3. Securely clamp the assembly together including the rod with a series of washers or a spacer to hold the rod the required extent while you peen the first side. You may need an assistant to hold a "dolly" against the rod on the opposite side while you do the riveting on your side.
4. Use a large ball pane (Peen) engineers hammer say 2lb and by using the ball gradually peen around the circumference. You will get the idea. Try a dummy run with some scrap first. Happy riveting, I have to go sailing......

[glynn]

Thanks for the tips. I knew some-one here would know.
I used to go sailing 'til I decided to build a boat!!!
Glynn

[JimL]

Hi Glyn, How did you get on with the peening?riveting of the rod? Hope it went well. Cheers Jim.

[glynn]

Hi Jim,

I think the best I could say is that it's done now, and once on deck hopefully no-one will notice all the dents in the lovely bronze plate!!
As is usually the case, the practice run went really well, and the head formed easily. Then I started on the important bit and whether I hadn't heated the rod as well or eight were just too many to do at once , but I had to beat that copper rod with all my might, and left marks on the sheet to remind me forever.

I can see the peice from here and still cringe, but I now find I have to do the same on the rudder, for all the fittings, so only another forty to do. As the designer keeps telling me, by the time I have finished I'll be good at all sorts of things.

Perhaps I need a more gutsy blow torch, rather than using the one from the kitchen that we use for trendy puddings.

Glynn

[benz]

Don't feel bad about the dings in the bronze, Glynn. If I could post a picture I'd show you how my recent gudgeon-riveting job went, where it seemed I hit the gudgeon more than the actual head of the rivet. Fortunately it will be underwater practically forever.
Ben

[JimL]

I think I may have an answer to the problem and I appologise if I have caused any confusion.
When I said anneal, that means to heat the rod up to cherry red and then let cool. When the flame is off the copper it looks a dark red and when the flame is on the rod it has a shiny appearance. You can let the rod cool down slowly or quench it in water to cool it quickly. It will not effect your material.

Because it is non ferrous i.e. copper or bronze it will work harden as you form it.
When it work hardens, then you need to anneal it, again. It is not necessary to have the rod red hot when peening. Now if it was a steel rivet, that would be different.

Steel rivets were/ are heated to near 'white hot', not to be easy to form over, but to ensure that the shank of the rivet fully fills the hole. You can actually knock a 0.75" rivet head down cold but it will never be tight in the hole.

Let me know how the rudder goes