Re: [CAD_CAM_EDM_DRO] Easy to make digitizer..(yeah sure)

I have an idea that "might" make a really simple way to digitize parts.

I remember back at school where we used a "home made" fixture and created a
"tracer mill" out of the bridgeport.

If the CNC machine still had the manual handles:

Set up the tracer mill fixture, install a part you want to copy, use all the
tools you would normally use and actually machine a part. While this is
being done, could the CNC system be set to read in all the moves you make by
hand?

The only thing you'd have to be sure to do here would be to set the tool(s)
to known dimension(s) so as to be able to repeat the cutting depths when
using CNC the next time.

Does this sound feasible?

Smoke
-----Original Message-----
From: dougrasmussen@... <dougrasmussen@...>
To: CAD_CAM_EDM_DRO@egroups.com <CAD_CAM_EDM_DRO@egroups.com>
Date: Wednesday, November 15, 2000 8:20 PM
Subject: [CAD_CAM_EDM_DRO] 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
>
>
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