Re: VFD tachometer sanity check

Harbor Freight has some digital multimeters for $3 at the momont and
it occurred to me that at that price you could afford to hack one of
these up for a tachometer display. Andy

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "James Cullins"
<jcullins@c...> wrote:

> Jeff
> Ok, you are reading the RPM as a voltage of 0 to 10v and

converting it to

> RPM reading, should work fine, are you using a digital display?
> Jim
>
>
> Jim
> ----- Original Message -----
> From: "washcomp" <jeff@w...>
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Sent: Saturday, November 22, 2003 1:09 PM
> Subject: [CAD_CAM_EDM_DRO] Re: VFD tachometer sanity check
>
>
> > Jim:
> >
> > Yes. I was figuring on using the max RPM reading (on a voltmeter)
> > to be calibrated to 10 volts analog output which is linked to the
> > frequency.
> >
> > Jeff
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "James Cullins"
> > <jcullins@c...> wrote:
> > > Jeff
> > > I have been thinking about that myself. Wouldn't you need a

way

> > to set up
> > > the max RPM
> > > to indicate the RPM correctly?
> > > Thanks
> > > Jim
> > > ----- Original Message -----
> > > From: "washcomp" <jeff@w...>
> > > To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> > > Sent: Saturday, November 22, 2003 7:40 AM
> > > Subject: [CAD_CAM_EDM_DRO] VFD tachometer sanity check
> > >
> > >
> > > >
> > > > I'm thinking of buying a variable frequency drive for my
> > Bridgeport.
> > > >
> > > > The 10 Volts off the analog contacts of the VFD can be set to

be

> > > > proportional to the frequency.
> > > >
> > > > If the RPM is linear to the frequency (after slip has been

taken

> > > > into account), and if the voltage is linear to the frequency,
> > then
> > > > shouldn't the voltage be linear to the speed?
> > > >
> > > > If this is the case (the real question I'm asking), once the
> > setup
> > > > is calibrated, this should give the ability to have an

accurate

> > > > electronic analog tachometer on the control pendant I'm

designing

> > > > without resorting to an additional optical encoder.
> > > >
> > > > I figure a tachometer would be useful for "manual" machining

and

> > > > sanity checks on CNC milling.
> > > >
> > > > Any thoughts, comments or suggestions would be appreciated.
> > > >
> > > > Jeff
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
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> timg@k...
> > Moderator: pentam@c... indigo_red@q... [Moderators]
> > URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> >
> > 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
> >
> >
> >
> > Your use of Yahoo! Groups is subject to

http://docs.yahoo.com/info/terms/

> >
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> >