Martin H. Eastburn wrote:
One of the possibles - have the bolts in the floor - and through the
equipment with
nuts on - but not tightened onto the metal. e.g. trapped from walking
or bucking - e.g.
safe from problems - but not torking the frame out of shape as it flexes
in temperature
during a season or day.


That is a good idea Martin.

The room these machines are in is temperature controlled. Over a year it
does not vary much more than 10 degrees F. By my estimation the length
of the cabinet will vary by about 0.00584" for a temperature change of
20 degrees F. The cast iron lathe bed by about 0.00472" and the concrete
floor by about 0.0064" over the distance between mount points. The
difference in length change is greatest between the cabinet and the
bed... about twice that of cabinet and concrete. Naturally the actual
geometry of the interactions can make a much larger change in alignments.

The way the bed is mounted to the cabinet appears to be designed so
there can be some variation in the distances between mount points over
time and temperature. Each mount point has an externally threaded
bushing. The external thread on the bushing mates with internal threads
on the actual bed of the lathe. The threads on the bed of the lathe pass
right through to the underside of the bed. Then there are bolts that
pass through the top of the bushing, down through the bed, through the
cabinet top with nuts and lockwashers underneath. There is some
clearance around these bolts and the ID of the bushings they pass
through. The leveling of the bed is done by screwing the bushings up or
down as required.

The manual from the manufacturer for this lathe claims that alignment
was done at the factory before shipping by mounting and leveling the
cabinet properly and then leveling the bed.

The bolts I was intending to use for mounting the cabinet to the floor
will be smaller than the holes of the mounting tabs on the cabinet. 1/2"
holes and 3/8" bolts. I could use 1/2" bolts as the holes are slightly
larger than 1/2" some are even elongated but I don't think I can drill
the holes in the concrete that accurately.

Seems to me that experience, opinion, and practice is mixed on whether
to mount the lathe to the floor at all.
Personally, I want to do the method that gives me the most precision.
Practically, I have to do the method that I am required to do which is
bolt the machines down.
This isn't a home or privately owned shop.

Thanks again for your suggestion.

-DU-...etc...