Re: [CAD_CAM_EDM_DRO] Re: Rotary to linear translation AHHA! (plus an idea for backlash free gearing)
Posted by
Jon Elson
on 2000-04-12 13:00:51 UTC
Jon Anderson wrote:
debatable. I think
there is going to be some significant wear of the edges of the wheels,
andf maybe
the rod, as well. As the wheels wear, or the rod wears, bringing it in
contact with
a different part of the wheel, it is going to slowly change the
effective diameter of the
wheel. I am imagining wheels with semi-circular grooves in the edge, so
that the
shaft wedges into the groove a bit, drastically improving the friction.
I think you have
to apply the wheels to the rod with a substantial amount of force to
avoid slippage,
even with very low friction bearings on the wheels. It might be
possible, especially in
home shop use, to recalibrate the thing yearly or so with gauge blocks.
If most of the
wear is on the wheels, it should stay accurate. If the wear is on the
rod, too, then
the most used area will show more error, and it will get non-linear.
The more
worn-down rod will ride lower in the groove on the wheel, thereby
reducing the effective
diameter of the wheel.
Jon
> Using the opposed disks rolling against a hardened rod, everythingThe usefullness of this design for commercial applications is
> could
> be totally enclosed in a housing, the shaft sealed with standard shaft
>
> seals, and you have a reliable, backlash free, accurate position
> sensor.
> Heck, I think I'd try to patent the idea if I hadn't just made a
> public
> disclosure.
debatable. I think
there is going to be some significant wear of the edges of the wheels,
andf maybe
the rod, as well. As the wheels wear, or the rod wears, bringing it in
contact with
a different part of the wheel, it is going to slowly change the
effective diameter of the
wheel. I am imagining wheels with semi-circular grooves in the edge, so
that the
shaft wedges into the groove a bit, drastically improving the friction.
I think you have
to apply the wheels to the rod with a substantial amount of force to
avoid slippage,
even with very low friction bearings on the wheels. It might be
possible, especially in
home shop use, to recalibrate the thing yearly or so with gauge blocks.
If most of the
wear is on the wheels, it should stay accurate. If the wear is on the
rod, too, then
the most used area will show more error, and it will get non-linear.
The more
worn-down rod will ride lower in the groove on the wheel, thereby
reducing the effective
diameter of the wheel.
Jon