On Saturday 07 March 2020 00:13:38 Gene Heskett wrote: > On Friday 06 March 2020 21:50:15 Jon Elson wrote: > > On 03/06/2020 05:38 PM, Gene Heskett wrote: > > > I have now put 2 ATD667LSG's on this block and have failed to get > > > a working index pulse into linuxcnc thru the encoder index pin of > > > a 7i76D. > > > > Note these sensors are open-collector, so need a pull-up > > resistor. > > > > > I've mounted it branded face against a block of alu, with a green > > > 3 pin socket to allow unplugging it quickly, and I jbwelded a > > > piece of a nail to the side of the drawbar cap/bolt retainer at > > > the top of the spindle, but I can't get a false out of it at any > > > orientation of the nail or a tool waved past it. > > > > The sensor is on the end where the leads come out of the > > package, but at right angles to the > > leads. That's the "branded face". So, it sounds like you > > have them mounted backwards. > > That cross patterned face is then a target to be machined into the > mount to locate it more precisely? I'm in the house but I now seem to > recall that its the smooth side that's facing the gear in the lathe. > Duh. It takes a 16mm projector lens and damned strong light to read > the text printed on the "branded face". What the hell were they > thinking? > > You're saying that the depressed cross in the 5% smaller face is not > the sensed face? That the crossed pattern should be the face glued to > the mount? In that event I also have them wired reversed polarity. > Which shouldn't hurt them as they are rated for up to 18 volts of > reversed voltage. But by now, I'll have to do some chisel work to > remove and likely wreck a 2nd one. Sigh. This is what they mean when > they say an education costs money... I only bought 6, paying about $2 > more from digikey because all the $6 ebay ones were in the middle of > the virus in china and 6 weeks away. > > Thats also an excellent example of a piss-poor 14 page document they > supply. That cross grooved face is much easier to identify. And mount > to the smooth face, the jbweld oozing out can also cause lead shorts > much easier. > > > The gear tooth needs to wipe sideways across the sensor to > > be registered. So, a gear > > tooth that is parallel to the leads will be sensed as it > > wipes across the face of the sensor. > > Or in this case, 1/2" of a 2" nail, jbwelded to the outside of the > drawbar retainer cap which will swipe across the smooth face as the > spindle rotates. > > Now I am pissed at me. > > > Motion of the tooth will be at right angles to the leads. > > > > Check if the sensor +5 V is drawing any current (should be > > about 7 mA). Are you sure you have not > > connected to the "test" output (pin 3)? They don't say what > > this pin does, just tell you "tie to ground or > > leave open". > > Which I've always clipped off... > > > Jon > > Thank you Jon. > Now, it looks to me that the only non-ambiguous drawing in that whole document is the one on the lower left on page 8.
But read the text. It seems to me that the rotation reversal is going to diddle the vertical positioning if there is any encoder counter reset allowed while the locked condition is in effect. It doesn't give me any confidence that the vertical positioning will be error free at all. What I do know for sure is that if because the tap is too big to pull in one g33.1 pass due to lack of motor power and I have close to 2hp I can surge it to, and I write the rigid tap routine to peck the operation by driveing the tap only 1/4 to 1/2 a turn per "Peck" until the depth has been obtained, that the repeated passes give me an obviously loose fit to a bolt, which I have until now blamed on a backlash take-up error. What I haven't done is played with the backlash to see if the somewhat sloppy thread obtained by peck tapping can be improved. But I also don't know if a counter reset is done anyplace but at the instant the down-stroke is started. But that text tends to tell me that since the pulse polarity depends on the rotational direction, then the phasing relationship is going to be diddled by quite a few counts at the bottom of the hole when the turnaround and backout move is begun. How can one determine if thats the case? Its going to be very hard to see on the halscope unless a 50 u-s base thread just to run the halscope is setup, something I don't have now. This is, I think. probably in the 5i25 firmware and I'm not qualified to troll thru that. I can't even imagine how that might be alleviated, even by an automatic edge detector. Even if the polarity is reversed with the direction of rotation, it has to be reset probably several counts ahead of the true zero point as the nail crosses over the hall effects gap, before it can send that edge again on the next rotation. So which edge do we use to get the least error? Seems to me the first edge should be ignored because that would be the reset edge to be thrown away. Given that my encoder count per revolution is something north of a scale setting of 14,000 when the head is in low gear, a 5 degree error because its triggering on the first edge, can be quite a few counts difference depending on the direction. So the second edge as its "tooth" sweeps across the gap, would be far more accurate. Some sort of logic to control which edge is used, controlled by the instant state of the a/b detectors direction output. Can you shine any light on this, Peter? Or am I years late to this discussion? 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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
