Re: [CAD_CAM_EDM_DRO] differential threads for extreme precision movement

>
> << With such ratio's as these, there should be no requirement to use
> pulleys to increase leverage, so the motor can direct drive the shaft.
>
> There are of course some interesting "details", which I leave up to
> the "sufficiently curious".
> >>
>

One problem you may encounter is frictional resistance between the screw and
nut, which increases with the speed of the screw. Lead screws are designed
for boundary layer lubrication. To get reasonable rapid traverse with such
fine thread pitch you will cross the speed barrier from boundary lubrication
into the hydrodynamic lubrication region. The close tolerances you need to
minimize backlash are not favorable for this to occur. The result is that
the lubricant itself will cause frictional drag. This is the same thing
that causes an engine to overheat if you use a higher than recommended oil
viscosity.

You won't solve the problem with light viscosity lubricant either, as this
will not provide the boundary lubrication necessary to protect the screw and
nut.

Doug