Thread: Squashed metal sphere

fireplaces are made from cast iron as other steel would overheat and melt.

im sure it would not work to make it out of plate otherwise it would be easy.

Originally Posted by weisyboy

fireplaces are made from cast iron as other steel would overheat and melt.

im sure it would not work to make it out of plate otherwise it would be easy.

what do they put in the water up there that could possibly make you think 3mm plate steel would melt in this particular application?

well not melt but u knwo wht i mean. (maby you dont) it would becoe red hot verry quickly.

I say 3mm plate because this is the actual specs from the US installation/compliance manual. The steel is coated with a 900deg resistant paint. Total weight (excluding the flue) is 97kg. The manufacturer also has some other designs that are made from 4.5mm.

I think it would have to be spun in two sections and then welded. The high temp coating applied afterwards, kind of like a weber bbq.

One thing though, while it looks great, it would be an unguarded accident waiting to happen. No way you'd have a party and a fire on the same day.

Greg

the bottom half at least is just like a disc plough dischttp://www.csn.com.au/series570.htm
lots of these have been used for bbq plates and will take years to wear out .Try john shearer for details

Originally Posted by gregoryq

I think it would have to be spun in two sections and then welded. The high temp coating applied afterwards, kind of like a weber bbq.

One thing though, while it looks great, it would be an unguarded accident waiting to happen. No way you'd have a party and a fire on the same day.

Greg

yeah thats my thought too. They can spin metal up to 3mm thick and 1200mm dia. Ultra cool, but yeah not the best for kids to be around. Still, whats the worst it can do? Give them a nasty burn, you can be sure as hell that they would never touch it again.

It appears to be fabricated from standard parts, called "dished heads" in the trade. Their most common application is for the ends of tank cars and trailers, but I've used them elsewhere. There are many sizes, shapes and configurations available, notably the vertical flange(s) at the periphery (see the weld bead inside at the far side), and the nozzle at the chimney. Any metal fabricator worth his salt should be able to make this for you; I doubt they would be willing to sell parts only, though. The supply pipeline is narrow.

If you say the magic words "dished head" in your enquiries, at least they'll know you've done your homework.

Cheers,
Joe

Hi
Joe is correct.Even here they are called dished ends.

The closest they appear to have off the shelf is a torispherical shape.
You can buy 2 and have the flange edge cut back and butt welded together.
You won't want the one in the picture ,but its an example of what you can go to.
or two

heres a link or two

http://www.dishedends.com.au/profile.htm

http://www.forbesaust.com.au/new/dishedends_pv.html


Grahame

Thanks all for the input.

Over the course of today I've learnt a lot about dished ends and how they are made. I've sent a couple of drawings off to some fabricators to see if they can do something like this. We'll see what the response is like.

I'm sure I can have something made for a cost somewhat less than the $18,000 (!) that this fireplace costs from the importer.

Cheers, peter

awesome, who'dve thunk.

So any idea what one of these dished ends would cost, say a 1200mm dia one? I'm thinkin they're prolly not cheap.

I reckon that $800/$900 each would not be too far off the mark.

I would also say the vendor could cut back the edges to your specs and provide weld prep.

There are concentric pipe reducer pieces that the funnel top could fabbed from

The cut for the open face may have to be done in another shop.

See the pic ,obviously the big diameter on the bottom and the small one to your pipe.Any competent pipe work boilermaker could handle it.
Dress the welds flat, sandblast and paint with heat proof. Even in 4mm its going to weigh a couple hundred kilos.

Grahame

Thanks for the links, Grahame.

Another term of art I've heard is "bumped" head or end. In the early 1980s, Lukens Steel in USA stopped publishing their catalog of shapes, to remove guidance for competitors, although it isn't exactly rocket science. High-volume production may be by pressing vs. spinning. IIRC, thicknesses up to 3/8" (9mm) were available.

Your best bet will be to provide a range of acceptable sizes and shapes, and let the fabricator suggest standard products, which might even be available from inventory. I have the impression that odd sizes might be spun or pressed to order, with longer lead time and expense, especially if dies have to be made.

Cheers,
Joe

I wouldn't go trying to sell these. They are a "design classic" aren't they? (Which is why they are $18,000. ) Or maybe you could. Call it a reproduction.