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 > >> > > > > > > > _______________________________________________ > 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 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users