Re: cast iron and lurkers

I too have really enjoyed this long thread.

It was after reading about ageing cast iron for days, then watching a
show on PBS about world war II figher planes.

The extradinoray developemnt of technology in such a short time, from
bi-planes to jet fighters... OK, so back to cast iron.

Obviously there was absolutly no time to age an engine block for a
fighter plane or even the huge blocks for freighter ships and tank
engines. Many planes and ships were lost well before the engine
block even started to stress relieve itself from natural causes.

I know that we chase molecules for accuracy, but how bad was it in
those days? did they have head gasket leaks or siezed motors? or
just sloppy fits and let the grease and oil fill the gaps? We may
never know becasue this thread doesn't go back that far. :)

From what I've gathered, heat treating can do a goodly amount of
relieving the pressures, both crystiline and stress, and the aging
cycle does even more. Seems if I was to build a new machine, I'd be
too impatient to wait. If I had the funds, I'd get two castings.

I'm waiting for my 7x10 to arrive. HF, ordered in late Janurary,
already got my first notice it's B/O. :( I will be very careful to
inspect the linearity of the ways, and will put it on a surface plate
to check the parellel tolerance of them too.

I almost want to order a second, and leave it in the back yards for a
few years. If I went that far, I'd have to chrome the ways for
longevity.

This site is invaluable to someone like me. No experiance because
the lathe hasn't arrived yet, but I already know what to look for.

Thanks all.


Dave

--- In CAD_CAM_EDM_DRO@y..., "R. T. Robbins" <rtr@n...> wrote:
> This list has quality people - the regular contributors and the
lurkers.
> The regular contributors have great insights on a wide range of
relevant
> subjects. The lurkers add their considerable experience when
appropriate.
> It is silly to judge a list by the number of posts. The quality of
the
> posts is so good that strings like "cast iron" are a joy to all of
us.
>
> We are all busy people. Filling this list with garbage reduces the
> membership because we then have to wade through too much stuff that
isn't
> relevant to our interests, or to which we have nothing useful to
add.
> Twenty or 30 posts a day from this large list maintains high
quality. I
> know really good people have had to leave the list because they
don't have
> time to wade through 40 or more posts on a daily basis.
>
> On to CAST IRON! I have done substantial work in the plants of the
makers
> of large machine tools. I saw large, expensive castings rusting in
the
> snow and asked about the reasoning for tieing up the working
capital in
> castings aging in snowbanks. I was told that they (In agreement
with
> earlier postings.) had to cycle through long seasonal changes, and
that
> there wasn't enough temperature changes in the sunbelt.
>
> I suspect there are other historical reasons for machine tool
builders
> locating in less pleasant climates, but the argument for thick cross
> sections needing these long temperature cycles, sometimes lasting
more than
> a single year, is, in part, that this source of energy is cheap and
> effective. There is little invested in a raw casting sitting out
in the
> weather. During recessions, they just continue to sit outside,
consuming
> relatively little cost, but they are ready when orders pick up
again.