"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 3.70...
"PrecisionmachinisT" fired this volley in
news:jsGdnfYr1aSnbp3TnZ2dnUVZ_rudnZ2d@scnresearch. com:

On a rocking ship, a level.is more useless than a lawnmower.


OhhhKay... I guess I wasn't referring to "level", but how to keep a lathe
true on a deck that might bend under it.


Sorry, but I couldn't resist..


I don't know, but they might've even trucked those lathes into the
maintenance bay pre-mounted AND pre-trued on those big slabs. For sure,
they won't warp before they break.

Actual _level_ isn't all that important unless you're turning really
heavy work with a long overhang. Close is good on leveling, truing must
be perfect.


When you think about it, the machine that ground the ways would have had to
be perfectly "earth level" in order for it to be able to grind ways that
would end up being "earth level"...and so on...

The reality is, "earth level" is nothing more than a good reference point
that you can always to go back to if things seem to be getting worse instead
of better after you've started into fiddling around with the jackscrews.

That said, where you have a vertical column bed mill with 4 or 6 leveling
jacks, you most certainly can obtain better z axis perpendicularity by
taking it slightly off-level.....

....BUT...

--You still need to insure that there is roughly equal weight being borne by
ALL of the feet or else you are going to find that the bed will have warped
and the whole works is messed up probably even worse than before after just
a few days have passed.