Re: [CAD_CAM_EDM_DRO] CNC edgefinding/touch probe update

On Mon, 2004-02-09 at 12:25, Dave Dillabough wrote:
> Is the acu-rite probe magnetic? I have had occasional repeatability
> problems with a regular edge finder and a slightly magnetic work piece. A
> wipe with isopropyl alcohol should solve the cleaning issue. Watch out for
> burrs.
>
> At 08:52 AM 2004/02/09 -0700, Kim Lux wrote:
> >I ordered and received the edgefinding touch probe that I spoke of last
> >week. Specifically, we purchased an Acu-rite 38-80-00-155, which is an
> >electrical contact type probe (ie between the probe stylus and the
> >workpiece). The probe is self centering, with a 0.5" shank (ie works
> >with R8 collet mills...) and a 0.2" diameter tip. The stylus has about
> >1/2" of movement in each direction in case of over run. THe probe cost
> >$250, plus shipping. I have no affiliation with Acu-rite.
> >
> >There are less expensive touch probes on the market, but:
> >
> >a) they are usually battery powered and visual, ie they light an LED.
> >b) they don't readily tie into a CNC controller, although they could be
> >made to...
> >c) most have a 1" shank, ie they won't fit an R8 mill.
> >d) most have a 0.4" sensing ball, which is too large for a lot of holes.
> >e) most don't do Z axis touches. The Acu-rite does.
> >f) most have limited over travel capability.
> >
> >We mounted the the touch probe in our CNC mill, which is running
> >TurboCNC as the controller. TurboCNC had a G50 command for center
> >finding a hole. The G50 routine had a few bugs, which I fixed. I also
> >added a G51 routine for center finding on a protruding shaft and a G52
> >routine for edge finding on an ... edge !
> >
> >I've got mixed feelings about the performance of this setup. First, the
> >Acu-rite touch probe itself works well, ie it centers itself well, has
> >good over travel capabilities, etc. No problems there.
> >
> >The issue I have with this setup is that it utilizes an electrical
> >connection between the workpiece and the probe to sense when the edge is
> >"touched". In my (limited) experience, one must have perfectly clean
> >parts in order to get repeatable results. One can get Total Indicated
> >Runout measurements of 0.0004" on a hole, but it might also take 3 or 4
> >centering efforts to achieve that.
> >
> >I'll continue to refine our edge finding efforts. If anyone has any
> >advice, I'm all ears.
> >
> >--
> >Kim Lux <lux@...>
> >
> >
> >
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> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
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> Yahoo! Groups Links
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--
Kim Lux <lux@...>