Same here,

Martin

________________________________
From: Mark Wendt

Link no worky.  Returns an error "The Request Entity is too Large".

Mark

On Thu, Mar 31, 2022 at 2:30 PM Lawrence Glaister <ve...@shaw.ca> wrote:

> Hi Andrew,
> It has been a few years since I added a spindle encoder to my lathe. I
> have a web page describing the gruesome details that might give you some
> ideas and some gcode to play with for cutting the disks. This encoder is
> still in operation with the data being fed into a parallel port on an
> older PIII 700Mhz Del box running ubuntu 10.4.
>
> https://ve7it.cowlug.org/spindle-encoder.html
>
> cheers
>
> Lawrence VE7IT
>
> On 2022-03-31 10:10, Chris Albertson wrote:
> > On Wed, Mar 30, 2022 at 11:18 PM andrew beck <andrewbeck0...@gmail.com>
> > wrote:
> >
> >> Hey guys will this work OK?
> >>
> >> I think it's the same as the one from amazon
> >>
> >> https://www.trademe.co.nz/3531064367
> >>
> >>
> >> And I'm thinking I may need two discs.  One above the other so I can
> use a
> >> index sensor on the top layer.   Or maybe stick a proxy sensor on it.
> >>
> >> Looks like they have a 6mm gap between the slots in the sensor.   Do you
> >> think a 1mm wide gap gap would be ok maybe in a 2 mm thick sheet?
> >
> >
> >
> > The link does not work for me.
> >
> > Ideally the slots and the space between the slots is the same.   But this
> > only really matters if
> > 1) you intend to double the resolution by looking at leading and trailing
> > edges.
> > 2) and when the spindle reverses direction there is a small error if the
> > geometry is asymmetric.  Maybe the error is too small to break a tap, I
> > don't know.
> >
> > If the plate is thinck relative to the slot width all that means is the
> > alignment most be good, with the IR beam exactly 90 degrees to the disk.
> > The Omron senors, when you look inside use a very thin disk, like brass
> > shim stock. This minimizes any error caused by misalignment.   The very
> > high-end sensor use glass disks with vapor deposited aluminum to block
> the
> > light.
> >
> > Don't bother with two disks, because alignment can never be 100% perfect.
> >   Simply drill a hole for the index or make one slot deeper.
> >
> > A trick used in automotive sensors is to have one missing slot.  Then
> > software resets the counter when the expected pulse does not happen  This
> > saves the cost of the third sensor but that only matters if you build a
> > million cars.  IR sensors cost only about $1.
> >
> >>
> >>
> >>
> >> On Mon, 28 Mar 2022, 07:35 Chris Albertson, <albertson.ch...@gmail.com>
> >> wrote:
> >>
> >>> Forgot to include a link.  You can buy the bare sensor but also you can
> >> buy
> >>> them on PCBs with connectors attached and ready to go.
> >>> amazon.com/Measuring-Optocoupler-Interrupter
> >>> <
> >>>
> >>
> https://www.amazon.com/Measuring-Optocoupler-Interrupter-Detection-Arduino%EF%BC%885pcs%EF%BC%89/dp/B08977QFK5/ref=sr_1_17?keywords=c+optical+sensor&qid=1648405019&sr=8-17
> >>>>
> >>>
> >>> Best to use a thin aluminum plate to make the interrupter disk.   Make
> >> the
> >>> slots 50% duty cycle,    You need three sensors for quadrature with
> >> index.
> >>>   The above sensor should directly interface to Measa or a parallel
> port
> >> or
> >>> some microcontroler.
> >>>
> >>>
> >>> On Sun, Mar 27, 2022 at 10:02 AM Chris Albertson <
> >>> albertson.ch...@gmail.com>
> >>> wrote:
> >>>
> >>>> THis goes to 10K RPM?   that is 167 revolutions per second.  400 slots
> >>>> means 70 KHz signal.
> >>>>
> >>>> Can you design an inductive sensor that does 70KHz but is also
> >> sensitive
> >>>> enough for near zero RPM?   Optical sensors can work up to 1MHz with
> no
> >>>> problem as they don't have any inductanve.    You can buy a "C" space
> >>>> sensor for a few dollars
> >>>>
> >>>> In either case, optical of inductive, you want a 50% "slot" where
> there
> >>> is
> >>>> as much metal left as cut away  Then the "edges" of the square wave
> are
> >>> the
> >>>> same in either direction.     The 50% duty cycle in effect doubles the
> >>>> sensor resolution.
> >>>>
> >>>> Why?  Think about the signal when the direction changes.     You have
> >> two
> >>>> sensors in quadrature and lets say one is being blocked and one is
> not,
> >>> I
> >>>> think you want the turnaround to take as long for each sensor.
> >>>>
> >>>>
> >>>> On Sun, Mar 27, 2022 at 2:22 AM Andy Pugh <bodge...@gmail.com> wrote:
> >>>>
> >>>>>
> >>>>>
> >>>>>> On 27 Mar 2022, at 08:09, andrew beck <andrewbeck0...@gmail.com>
> >>> wrote:
> >>>>>>
> >>>>>> And is bigger dia better for higher resolution?
> >>>>>
> >>>>> Probably not, as it will perhaps have more scope to oscillate at
> >> 10,000
> >>>>> rpm.
> >>>>>
> >>>>> Don’t neglect the purely mechanical design of this fast-spinning
> part.
> >>>>>
> >>>>> Have you considered optical sensors rather than inductive?
> >>>>>
> >>>>> What will be counting the pulses?
> >>>>>
> >>>>> LinuxCNC can lathe-thread with one sensor.
> >>>>> But rigid-tapping is different as it needs to accurately detect the
> >>>>> reversal point. So you need three channels for index and full
> >>> quadrature.
> >>>>>
> >>>>> Work out what error you can accept in the reversal point detection
> >> (as a
> >>>>> fraction of thread pitch) and you can get a feel for how many slots
> >> you
> >>>>> need.
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>> _______________________________________________
> >>>>> Emc-users mailing list
> >>>>> Emc-users@lists.sourceforge.net
> >>>>> https://lists.sourceforge.net/lists/listinfo/emc-users
> >>>>>
> >>>>
> >>>>
> >>>> --
> >>>>
> >>>> Chris Albertson
> >>>> Redondo Beach, California
> >>>>
> >>>
> >>>
> >>> --
> >>>
> >>> Chris Albertson
> >>> Redondo Beach, California
> >>>
> >>> _______________________________________________
> >>> Emc-users mailing list
> >>> Emc-users@lists.sourceforge.net
> >>> https://lists.sourceforge.net/lists/listinfo/emc-users
> >>>
> >>
> >> _______________________________________________
> >> Emc-users mailing list
> >> Emc-users@lists.sourceforge.net
> >> https://lists.sourceforge.net/lists/listinfo/emc-users
> >>
> >
> >
>
>
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