RE: [CAD_CAM_EDM_DRO] Re: CNC edgefinding/touch probe update

I'm wondering if the "sense current" to the probe needs adjustment or if
we've got a decent electrical connection between the table slides and
the controller. (The table slides are part of the circuit...)

Right now the probe is connected directly to the parallel port of the
computer. A 2K ohm pull up resistor is used in conjunction with a 5V
supply.

Kim

On Mon, 2004-02-09 at 19:37, Adrian Teo wrote:
> I use a similar setup with a electronic touch probe connected to a
> solid state relay that's used to buffer the 24V "skip" signal on the
> IO board/backend of the Fanuc (16i-M controller). Some tuning was to
> be expected (the on-off response of the circuit is tunable within the
> CNC control).
>
> -AT
>
> --
> ----------------------------------------------------------------------
> Adrian W Teo e: adrian.teo@...
> Senior Support Systems Analyst p: 480.965.9411
> Information Technology Instruction Support f: 480.965.6317
> Arizona State University CPCOM 233
> ----------------------------------------------------------------------
>
>
>
> > -----Original Message-----
> > From: kdoney_63021 [mailto:kdoney_63021@...]
> > Sent: Monday, February 09, 2004 6:44 PM
> > To: CAD_CAM_EDM_DRO@yahoogroups.com
> > Subject: [CAD_CAM_EDM_DRO] Re: CNC edgefinding/touch probe update
> >
> >
> > This is the setup I'm trying to do with a mitutoyo touch signal
> > probe. Do you have the setup information. I tried to set it up
> > through pin 10 with a pullup transistor but was unable to get any
> > response. How are you feeding the signal to turbocnc?
> >
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, Kim Lux <lux@d...> 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@d...>
> >
> >
> >
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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........
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--
Kim Lux <lux@...>