Easy to make digitizer..(yeah sure)

Group,

Here's my long un-acted upon method of building a mill type
digitizing unit.

First off, it requires a mill control with an M-code for activating
an external device. Sometimes that device might be an auxilary axis,
like a programmable index head. Most "professional" controls have
such an M-code, not sure about the "hobby" controllers. Wire that M-
code to a stand alone PC. The M-code is usually just a switch
closure in the CNC controller.

Use a digital dial indicator with data collection capability. Wire
the indicator to the stand alone PC via indicator's supplied data
collection cable. A program has to written in V-Basic or other to
control the data collection.

Put the indicator in a tool holder. Write a CNC program to increment
a set amount in the X axis, then downfeed the quill (indicator) a set
amount such that the indicator always makes contact with the item
being digitzed. (may need a long travel indicator) Once the quill
has reached it's downward travel issue the M-code. When the PC
receives the M-code signal it's program will cause the indicator to
send a data value which will be stored as a Z value. Note this is
only a Z value, the X Y values are assumed because we know the path
of the CNC.

After the Z value has been stored the PC can then signal back to the
CNC controller a completion signal for the M-code event. Then the
CNC goes on it's merry way repeating the above over the surface in
question as needed until the desired area has been digitized.

This method doesn't require any mods to an existing CNC controller
(provided it has an auxiliary axis M-code, which most do). It does
require some software writing for the stand alone PC. It also
requires user input to the PC software as to the exact X Y
cooordinates where readings will be taken since the reading is only a
Z value. By using an indicator tip matching a ball nose end mill the
data points could be fed into a cam program to duplicate the scanned
surface if that was the intention.

The worst part is digital indicators with data collection are kind of
pricey.


Make any sense?

thanks,

Doug