[TheForge] metal spinning

[terry l. ridder]

hello frosty;

thank you for the reply. i seriously
doubt that i would have the physical
stamina for metal spinning. i would
like to have a better understanding of
what is happening to the metal, by
what, and how. also to have contacts with
metal spinners in case i would need to refer
someone to one.

it appears that the metal is being deformed
, stretched in one location and compressed in
another location. given the starting shape of
a metal circular disk and the ending shape for
example a simple right circular cylinder. a
stock pot. there is some serious plastic
deformation occurring but i am not understanding
where and how. that is what i would like to
understand.

On Mon, 25 Feb 2008, Jerry Frost wrote:

> Terry:
>
> If you want to make an analog using clay,
> look to a potter's wheel. They not only
> look like the same process is going on,
> it is in large part the same process.
>
> As the tool is passing over the blank the
> metal is usually stretching to conform,
> however it can and must be upset as well
> to prevent failures.
>
> Rotation speed is determined by a number
> of variables: dia., material, thickness,
> shape of the finished part, type of tooling,
> (specifically, hand > vs. scissor tools)
> personal preference and skill among other
> lesser factors.
>
> Annealing may or may not be necessary depending
> on many of the same factors that determine
> rotation speed. Pure Al is generally easily
> spun without annealing as long as the shape
> isn't too extreme and the spinner's skill 
> level is decent. Most people are taught using
> Al as it's so easily spun. On the other hand
> the wrong type of Al can be a real PITA to spin,
> most of the AL we spun in Father's shop was far
> FAR from easy to spin. I thought SS was easier
> and most spinners look on SS with fear and dread.
>
> My personal favorite is mild steel, it likes to
> go fast, (high rpm) responds well to a sensitive
> touch and almost never fails catastrophically. (read 
> flying shrapnel) Brass is a PITA usually requiring
> multiple heat treats unless you're spinning a very
> simple shape or one you can really hog.
>
> Copper is like spinning taffy, requires little
> force and spins really well but work hardens
> suddenly so you have to be on your toes and
> have a good feel for it. Still, copper is good
> teaching material.
>
> I don't know of any good books that cover the
> kind of spinning we did in Father's shop; we
> were a production shop and used almost exclusively
> scissor tools. Most people spinning manually now
> use hand tools and I'm unfamiliar with the technique.
> I'll have to ask a couple of my old contacts and
> then get back with the name of decent books.
>
> However, on the practical side. Are you thinking
> of trying metal spinning Terry? If so you're not
> going to meet with much if any success, it's VERY 
> phisical and if you let it get away from you
> extremely dangerous. Think about a 6-9" diameter
> metal blank spinning maybe 3,000 rpm. coming out
> of the lathe and ripping it's way up your arm. A
> part can also explode if pushed too far or hard
> and the shrapnel can be almost impossible to avoid.
>
> I've personally practiced 1st. aid on the aftermath.
> On one occasion it took three of us to apply pressure
> to enough places to control the bleeding. 
> Though nobody died in Father's shop a number of guys
> lost fingers, the use there of and in one extreme
> case his entire hand. Dad's insurance paid for LOTS
> of stitches.
>
> Metal spinning can be very challenging, intensely
> satisfying, hypnotically beautiful to watch and
> cripplingly dangerous. It also takes a number of 
> specialty or specially modified machines.
>
> Frosty
>

-- 
terry l. ridder ><>