Making a metal cap for a wooden post

[Spamlet]

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Just reminded me of our old 'Ericson' tester: basically a metal ball pushed into sheet metal to test it's ductility. We had stacks of little domed plates... If you have a decent hydraulic jack or press and a metal ball and ring to push it through you might be able to cold form your shape. Be bold: you could even do something like jacking the car up with your plate and a former between. You could hollow a block of wood and use your fence post wooden ball, and the jack to push it in. Lots of uses for jacks...

If you are knocking up from scratch, the rim is the bit you are holding. Finish it last, then cut off the excess with snips (or snips, then finish: depending on how hard it gets). If memory serves that is...

S

[Spamlet]

Or just pour lead into and tip out when cool... Any non-melty bowl shape will do.

S

[Andy Dingley]

You don't desperately need either of these for this - work it with a mallet into a bag. This will also work-harden it adequately, so won't need a separate planishing step. As it's for outdoor use, not polishing, there's no need to plansih it for the benefit of the surface finish. Although you would need hammers for planishing, the shaping is best done with softer mallets.

[Andy Dingley]

Not the easiest job, to work stainless like that!

[Tim Downie]

In the end, I got some roofing lead and have battered it into shape. Apart freom needing a little trimming up, it doesn't look too bad. Now I need to make sure that it stays there on top of the post. (It will be accessible to the public). Any suggestions as to what kind of glue would be best?

Tim

[The Natural Philosopher]

no glue at all. Nail the side with galv roof nails or similar.

Very few glues work in regimes of vastly variable humidity. Those posts will MOVE.

Something rubbery and gap filling is possible, but that's about all.

Hot glue maybe.

[pete]

Most glues don't work with lead. The metal forms a layer of oxide which is not strongly bonded to the underlying metal. It may stick for a short time, but in due course it will come loose. Then you've got differential expansion - the metal will expand/contract due to temperature differences, more than the wood does. That puts more strain on the joint and will cause the glue to crack.

[Tim Downie]

I really would like to avoid nails. The domed cap is meant to be symbolic of a departed friend's bald head. Adding nails to it would lend it a certain "Frankenstein" air.

Is there no heavy duty flexible mastic/glue that might stick if I were to score the lead deeply on the underside?

Tim

[The Natural Philosopher]

mastic is a better bet than glue. I am trying to think of a rubbery type product that adheres well to metal and is gap filling too. silicone peels to easily from anything.

Maybe expanding foam would work..Hmm. That could be best of all. That's fairly flexible and sure fills gaps.

Not as rubbery as one would like, but its flexible enough, and it sticks like shit to everything.

[Andy Dingley]

None. Thermal expansion of the lead is a problem.

Best solution is to lead burn strips of lead onto the underneath, then nail those down with clouts. Then dress the dome back into place over them.

[Frank Erskine]

Car body filler.

[The Natural Philosopher]

Not flexible enough. It will crack off the wood.

[Huge]

I'd be inclined to try "Sticks Like Shit". It appears to do what it says on the tube.

[Tim Downie]

In the end, I decided that beating and shaping copper was beyond my skills so I went for lead. I started with a circle of roofers lead flashing and basically beat, pummelled and bent it into shape with a combination of wooden mallet and G-clamps. Pretty crude but it seems to have done the job.

advice, I have glued it with something called Stixall made by everbuild . Only time will tell how well it lasts but it's seems bl**dy well stuck on.

Just in case anyone was interested in what I did in the end...

Tim