Making a metal cap for a wooden post

In message , Tim Downie writes

You could go with the BT solution to telegraph pole tops and use an inverted V.

regards

Copper would be fairly easy, as long as you have a suitable wooden former. Wickes sell round balls for the top of newel posts that would be ideal, =A39 IIRC). You'd need to anneal the copper a few times so a blowtorch would be handy. Any model engineering supplier can sell you a suitable piece of copper.

Copper? You could solder/braze it.

buy an aluminium mixing bowl.

That sounds like a good idea. Ta.

Tim

Nah, for sentimental reasons it has to be domed.

Tim

Copper. Easiest to work, patinates nicely afterwards.

Tools are a variety of wooden, plastic or rubber mallets and also a mix of treestumps with hollows in, or else sand-filled bags. Most importantly, some sort of gas torch (or cooker) for annealing. You need something with these tools, but they're not fussy and it's easy to improvise. A cheap wooden egg mallet, or just a home made "lump on a stick".

Source metal is scrapyard immersion heaters, or other scrap copper.

Web searching should give you techniques, otherwise any '50s school metalwork handbook. Look for "sinking" and "doming"

Long time since school metalwork, but I would think making a ball from sheet would be v difficult. Think you would need to make two 'bowls' and solder them together. Also, the vandal and tea-leaf, dimension would mean that the post has to be away from anywhere it can be seen. Even then, leaving it hollow is inviting it to be squashed, however careful you try to be.

Using the wooden post top as a pattern, you might be able to cast one from solid lead if you have a safe spot.

Think we've covered post tops before. I made wooden caps for posts on a fence I made. Screwed them on with stainless. The local kids just split the wood off with a screwdriver. Didn't seem worth the bother of trying again.

here is a useful company to ask

But I'm not making a ball, I just want a metal covered domed top to the post, a hemisphere.

Well yes, but then I wasn't planning on leaving it hollow. As you say, it would make it too easy to dent.

Tim

Half a copper ball-c*ck ball?

Owain

Good bit of lateral thinking, bit big for a the top fo 4" post but

I agree, I'm no panel beater but just thinking about how a flat sheet of metal will need to stretch and bend to form a hemisphere is non-trivial. One might be able to get a half hemisphere without a skirt fairly easily but a full one which self forms to a skirt would be much harder.

The second link has 4.5"

It might be easier to change the size of the post ...

Owain

If its a 4x4 post, thats 5.6" diagonal

NT

I have a collection of chrome plated copper teapots that I bought for a couple of dollars each, since people don't like using copper teapots any more. Perhaps you can find something like that in junkshops. Or copper ornaments that you can chop up.

He needs an old hot water cylinder, lots of copper sheet. They can be found at scrap yards or where new combi-boilers are being fitted.

Get a stainless steel bowl of the right size and hammer into into the shape that you want.

You still need a good hard and smooth anvil of the right curvature to get a decent finish - and polish the face of the hammers first. It is not that difficult to form a bowl from sheet, but you need to soften the copper regularly with a torch, and have a sandbag or similar to get the initial shape with hard blows from a round headed wooden hammer. Then you have a long but satisfying bout of 'panishing' tapping to do, to get the final shape and hardness.