Re: CNC edgefinding/touch probe update

Kim,

You might want to tap a hole for a "ground" lug in the machine vise
and/or table... (kinda like a welder does) That would make for a more
concise and probably more reliable probe circuit.

Hope this helps,

Ballendo

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Kim Lux <lux@d...> wrote:
> 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@a...
> > 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@y...]
> > > 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
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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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> --
> Kim Lux <lux@d...>