Re: Help WHAT THE HELL IS A FLOATING NUT

San,

Start with a typical old-fashioned square nut (as opposed to the more
common hex). Find some material EXACTLY the same thickness as this
nut, but larger size overall. Put a rectangular hole in this
material, such that the rectangle is the same size as the nut one
dir, and bigger the other. Now make two "cover plates" with a round
hole a bit bigger than the leadscrew diameter. Time to assemble:

Rub the nut on some emery paper to VERY slightly reduce its thickness.
Put one of the covers on the rectangle-hole piece, with its leadscrew
hole in the middle of the rectangular "pocket" just created by
asssembling these two parts. Place the nut in this rectangular
recess; and close with the other cover plate. Hold the covers on with
screws,glue, or whatever makes sense. The rectangular-holed part
mounts to your machine axis.

Can you see that the nut will be free to move one direction (because
of the rectangular recess it is in)? But also that it cannot move
axially along the screw(except for that little bit you sanded off to
make sure it was free "floating" in the rectangular recess)? AND,
that the nut cannot turn, because the rectangular hole is the same
size as the nut in one direction? This is a floating nut.

To have it float in two directions will mean the introduction of some
backlash, as the nut "turns" in the recess until it hits a "wall" of
the recess provided to keep it from turning. And there will be the
backlash already mentioned from the requirement that the nut be
thinner than the pocket it sits in...

In short, this is one answer for a low-cost machine when there is an
expectation that the ends of the leadscrew will not be accurately
mounted in relation to the machine axis and/or structure. It also
allows for the generally poor concentricity of movement of hardware
store threaded rod...

However, it exchanges one set of problems for the others mentioned.
This is not in itself a bad thing; ALL cnc machines are compromises
in some ways. But for a higher quality machine, I would choose a
different technique; a different set of choices...

Hope this helps,

Ballendo

> --- In CAD_CAM_EDM_DRO@y..., "santorelli333" <san3@s...> wrote:
> > In other words, does anybody have a simple

illustration/explanation

> > of the woorking priciple
> >
> > San