Re: [CAD_CAM_EDM_DRO] screwless focuser was Re: re:Re: Re: Is this too nuts to consider ?

Ah...I can see that....band saw blades creep off center due to that
principle if not adjusted properly.

For the purpose intended, I still think it would be simpler and quicker to
just make a shallow thread manually and install a very light end force Vlier
plunger in the outer tube to ride in the thread. The spring in the plunger
would take up any depth variations in the thread.


Smoke,

>Imagine one end of a solid rod shaft supported by three bearings (the
>outside of each bearing "rides" against the shaft, like centerless
>grinding). The three bearings are radially spaced 120 degrees apart.
>Assuming the bearing axes are parallel to the shaft, spinning the
>shaft will work as expected (the shaft will be supported and spin
>freely, AND will not advance longitudinally).
>
>NOW imagine that one or more of the bearings' axes is NOT parallel to
>the shaft... As you spin the shaft, it WILL 'creep' longitudinally,
>and the amount it moves will be determined by the amount of the
>bearing(s) mis-alignment. Note that if the misalignment is not equal
>between ALL the bearings, there will be 'fighting' among the three
>bearings...
>