re:Re: cast iron (stress relieving)

--- In CAD_CAM_EDM_DRO@y..., ballendo@y... wrote:

> Dave,
>
> This is good news!
>
> The vibrator you spoke of-- How did it compare with a vibratory
> tumbler (in magnitude of shake)?
>
> I used to use one for "settling" poured concrete tiles. Is this the
> type of thing you're talking about?
>
> Thank you in advance.
>
> Ballendo
>
> P.S. What about putting them(castings) in the back of an old pickup
> and driving over rough roads? What I'm really asking here is: How do
> you know when you're "done"?
>
> > Thermal cycling, mechanical vibration, etc all will work, if you
> > move enough distance to slip the stresses out<snip>

Actually now that I think about it there were two different machines
that we used. One had a clamp on vibrator similar to the concrete
shaker, (it needed to make the iron "ring" so that's why it was used
at night...way in the back). The other was some kind of induction
device that pinged it with a magnetic pulse. Much gentler, but it
took up to a week to finish.

as to how to know when was enough. For the shaker, or pounding
method, One of the old guys would hit it with a hammer before we
started and listen to how it rang, and then after it was shaken for a
while, everyone would stand back and he would hit it again in the same
place. If the stresses were out it would ring at a lower frequency,
and he would decide if it was enough. (it just sounded like banging
to me, but we never had problems if he said it was good.)

The fancy electromagnetic device had a timer and some sensor in it to
tell when it was enough. Might have been eddy current but I never had
a chance to really investigate.

If you are on a budget, bouncing in a pickup should work just fine.
The idea is to make the metal ring until it relaxes. (and the tone
drops some)

Dave