[TheForge] Bending steel

[Peter Fels & Phoebe Palmer]

Just for color, let me throw in old Dr Tinkerpaw's ( RIP) method.
First anneal the metal and remove sharp edges. Then dig a hole in 
leather hard clay soil of a slightly smaller diameter and greater depth 
than required. Place metal over hole.  Next load up your truck and drive 
back and forth over the piece annealing as necessary.  pf

Bob Ehrenberger wrote:
> Mark,
> 
> I make 18" bowls out of 16ga steel.  Which is about half what you are 
> looking to do.  The first one took over 5 hours and about killed me, but now 
> I can do one in under an hour.
> 
> My method is a bit crude but effective.  I use a truck tire rim as a sinking 
> form.  I get the steel hot in the forge lay it over the rim and wale at it 
> with a slege hammer until it starts to develope wrinkles. I then take it to 
> the swage block and hammer out the wrinkles with a rounding hammer. I get it 
> hot and repeat until it gets deep enough to where the handle on the sledge 
> hits the rim of the bowl, at that point I switch to a heavy sinking hammer 
> that will reach into the deep bowl. The deeper the bowl gets the less it 
> tends to wrinkle.
> 
> For something as big as you want, you may need to make a sinking hammer out 
> of one of those spike driving hammers you see at flea markets every now and 
> then.  It would have the weight and the reach needed for a big bowl/sphere.
> 
> PS: My portable forge is made from the end of a large LP tank which is a 2' 
> diamiter sphere. It would make a nice form if you can find one.
> 
> Robert Ehrenberger
> Shelbyville, Mo.
> eforge at centurytel.net
> 
> Date: Mon, 23 Feb 2009 17:34:33 -0800
> From: Mark Novak <mark at fireworkspdx.com>
> Subject: Re: [TheForge] Bending steel
> 
> I'm planning on cutting 1/8" sheet into irregular strips, likely 4-5"
> at widest, and then bending them and making them convex enough to
> ultimately come to a 3-4' sphere (though it will not be a complete
> sphere - there will be intentional gaps so that the object suspended
> in the middle of the sphere will be plainly visible).
> 
> I'm considering making a jig (like the large bowl of my swage block)
> that I can hammer it into hot, though I know there will be dents and
> distortion without some uniform press die... I'm hoping what ends up
> visible from the outside will either grind out or be attractive. :)
> 
> Since I have a tiny shop without any power hammers or presses, I'm
> hoping I can accomplish this with hand power or some jury-rigged press
> (thoughts on that?).  Thanks for your advice! Keep it coming, please.
> 
> Mark
> 
> 
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