Re: [CAD_CAM_EDM_DRO] Re: Scanning with Touch Probe

Or perhaps we could arrange a probe to have a ball part way down as a
universal bearing and for its upper end to move around a glass disk with
fine concentric lines within a double quadrature head - two heads at right
angles. Jeez, isn't that difficult to describe concisely! What I'm really
trying to suggest is a system similar to a normal encoder system linked to a
lightly sprung probe. The position of the 'ball bearing' (which may be
better as gimbals) would allow for magnification of the movement and so the
reading. Thinking about it more, it may be possible or preferable to use two
short strips of regular encoder at right angles and allow for their vertical
displacement from one another (which will affect the readings shown) in
software. I have no idea how you would sort out the software but I'm sure
something could be done along the lines of 'detect the first change in
position of the probe, stop the machine, wait a fraction of a second for
things to settle, read the two quadrature scales and work out the probe tip
position.' This is probably way off the mark and the job can probably be
done much easier with a couple of capacitative or inductive sensors (voice
coils like in a CDRom laser head?) but I thought it may stimulate
conversation. Anyone have any other ideas?

Ian

--
Ian W. Wright
Sheffield UK

----- Original Message -----
From: Track Burner <Creative_Player@...>
> Although I haven't taken the time to figure it out yet, it seems like this
> system moved until the probe touched the surface of the object, then
> stopped, then separately measured the amount of travel of the spring
loaded
> fiber touch point.
> That way your system has some time to coast to a stop after each fast
move,
> without being afraid of crashing the probe or loosing accuracy from
> mechanical overshoot.
> An inductive, LVDT like probe for short travel would be fairly easy to
> construct and calibrate I would think.
> Maybe this is an idea?