On Thursday 29 November 2018 13:59:51 Chris Albertson wrote: > I bought a few inductive sensors on eBay. These are surprisingly > repeatable and very precise. They are cheap and easy to use. THe come > in different diameters. The one I like best has M12x1 threads on the > body. > > Here is an example: > ebay.com/itm/DC-3-Wire-6-36V-Inductive-Proximity-Sensor-Detection-Swit >ch-NPN-LJ12A3-4-Z-AX-US/ > <https://www.ebay.com/itm/DC-3-Wire-6-36V-Inductive-Proximity-Sensor-D >etection-Switch-NPN-LJ12A3-4-Z-AX-US/162683352852?hash=item25e0aef714:g >:ZqcAAOSw3GtZxVse:rk:2:pf:0> > > Place this so that it detects the steel set screw that holds the drive > gear to the spindle. If there is no such screw then find a place to > install a steel screw that sticks out about 5mm and have it pass close > to the sensor head. > > For experiments, I made e 3D printed plastic bracket that has M12x1 > internal threads. The supplied lock nut is too crude. A 20mm deep > threaded hole holds the sensor more securely. The sensor has very > clean output and measures distance, as well as the "good" quality > microswitches. Use the leading edge of the pulse is an "index" > > BTW these are not so good for sensing gear teeth,
I'd expect that to be a speed problem in the sensor, inherent in inductive sensors. Not fast enough when gear teeth are going by at good speeds. I have a quite nice quadrature encoder I built in my 11x36 Sheldon, with 2 ATS-667's sensing the 60 tooth bull gears teeth passing, and a third watching the end of a headless steel screw gooped to the side of a tooth of that same bull gear. These are hall effect devices with a bit of autocorrection for distants's, so they give about 55% duty cycle pulses even with a wee bit of runnout in the gears turning. I am not PIDing the motor speed since its a vfd which is - maybe 5% of commanded speed depending on load. Because of the ATD-667's distance auto correction, this would not be a good home sensor, for that the absolute distance of the inductive sensor would be more accurate. > A "bolt head sensor" > is what these are. THey would make a very nice home sensor for a > mill. because they are water and oil proff with no moving parts and > are "non-contact" > > On Thu, Nov 29, 2018 at 9:46 AM andy pugh <[email protected]> wrote: > > On Thu, 29 Nov 2018 at 17:16, David Berndt <[email protected]> > > wrote: > > > > Ok, thanks guys. I'll go with a seperate encoder to pickup a once > > per > > > > > rotation count. Are there any requirements about on/off span in > > > relation to A/B. > > > > No, any once-per-rev pulse will do. > > As has been mentioned, unless you want to do peck-tapping you can > > probably get away without an index. > > I think that even gear-hobbing would work fine. > > You would need a proper index for spindle orient if there is a tool > > changer. > > > > -- > > atp > > "A motorcycle is a bicycle with a pandemonium attachment and is > > designed for the especial use of mechanical geniuses, daredevils and > > lunatics." — George Fitch, Atlanta Constitution Newspaper, 1916 > > > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users -- Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
