Re: Fred, Digitizing probe ??

--- In CAD_CAM_EDM_DRO@yahoogroups.com, R Rogers <rogersmach@y...>
wrote:

> Fred, I must not understand digitizing or have a misconception on

how it is performed. My understanding is, that a pattern is ran with
the X axis perhaps, back and forth, +/- with a stepover on each
pass. When the stylus is traveling along and a vertical surface is
encountered that is higher (Z+) than the present surface. What moves
the probe up to the higher surface? Or use a round stylus with a
radius greater then the height of the vertical surface? I can see
dropping off the vertical to a lower surface but, not the other way
around.

DeskCNC is directly controlling the machine while the probe is
scanning. Any "action" on the probe switch causes a reaction within
one step. That means either while the probe is traveling down to
contact a surface or when it is pulled up after contact, or
subsequently when it steps over to the next grid point.

If you watch the scan in progress, it appears to your eyes as if the
probe tip follows the curved surface up and down. If you were to
try to scan with a 1/8 stepover, you would be able to discern the
discrete moves. If the scan is done at say .005 inch in the along
direction, the probe tip path is very smooth.

If a vertical is encountered, the probe raises until it clears. We
have 3mm tips and 1/8 dia stylus extensions available which pretty
much eliminates the error that might be caused by the shank hitting
before the tip. The effect of this, even without using a 3 mm tip
is that the corner is about 1.5 mm radius instead of 1 mm. For
decorative/artsy type of workpieces this is well within the expected
tolerances for scanned items.

Fred Smith - IMService