Chris just reading your email again and looks like the sensors you linked are good up to 1 mhz so I'm good to go.
How wide a slot do you think they need to read the light through? If they could read 0.5mm that would be great But I probably don't need that accuracy. I just want it as good as I can get as I know I'll be tapping several thousand holes. 400 PPR x4 is 1600 PPR. M12 tap pitch is 1.75mm 1.75/1600=0.001mm Which is plenty lol. Maybe I'll try this. Can I use halscope to check the sensors are making good quadrature On Mon, 28 Mar 2022, 06:06 Chris Albertson, <[email protected]> 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 <[email protected]> wrote: > > > > > > > > On 27 Mar 2022, at 08:09, andrew beck <[email protected]> > 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 > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > -- > > Chris Albertson > Redondo Beach, California > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
