[TheForge] Re: Bending steel

[Mike Spencer]

> ...attempting to bend large, irregular strips of 1/8" mild steel
> into a shape suggesting a globe. Any thoughts on method and tools to
> do this bending/curving?

You don't say how big the "globe" is to be.  However...

I'm an indefatigable collector of "round things": pipe offcuts, rings,
tanks, etc. for use as uniform-diameter bending mandrels.  Especially
desirable are things with more or less spherical concave surfaces, for
just this purpose.  Making a wild-ass guess at the numbers, if the
width of your piece of 1/8" is less than about 2/3 of the radius of
curvature of the concave tool, you can get it nice and hot and hammer
it down into a concavity and onto a concave surface of (approximately)
the right diameter.

If this results in a rather bumpy, uneven surface on the workpiece,
you can planish it to get a nicely faired curve, (Not, obviously, with
a jeweler's 3 oz.n planishing hammer. :-)

Where to find the tool?  Cut-off end of a tank, steam-pipe pipe-cap,
steel or aluminum fishing buoy, unidentifiable cast iron object from
the junk yard.

You might also do this by cold sinking into a wood or lead block but
I'm a bit intimidated by your reference to "LARGE, irregular strips".
If these are a couple of feet wide and several feet long, I'm guessing
that cold sinking would take a couple of helpers and a *whole lot* of
tedious work.

Chris Ray like to use 10 ga. for his pieces and did a lot of compound
curved surface with stake raising and cold sinking.  I don't know as
he ever made complete, one-piece hemispheres of any size this way,
though.



FWIW,
- Mike

-- 
Michael Spencer                  Nova Scotia, Canada       .~. 
                                                           /V\ 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^