On Monday 28 December 2020 04:21:37 andrew beck wrote: > Just another little update. > > Got the spindle running. > > Then connected the existing spindle encoder up and can't see any > counting of pulses in the 7i77 encoder raw counts. > I _think_ the 7i77 has the same encoder facilities as the 7i76 has, and the 7i76D has 3 flea clip jumpers to switch it from TTL signals to differential signals.
The differential is quite low voltage and not sufficient to be seen by an input expecting to see a single ended TTL signal. So double-check your wiring and the 7i77 for missplaced jumpers. > Would love to have a List of reasons why not. Just so I can trouble > shoot it. You will probably need an o-scope to confirm what you have. > Things I know. > > It is a 5v differential encoder. Meaning its outputs are about 100 millivolts of change, centered on a 2.5 volt bias. > With A B Z channels. > > I think it is 1024 ppr. > > Wires are all pretty clearly marked. > I think I got it all right. Though I had to run it through a plug and > transfer cable signals to other colors so could have made a mistake. Another possibility. But diff encoders cables are both well shielded and generally long enough. I just bought another 1024 ppr Omron because the one on my G0704's spindle motor was getting flaky and that cable is a tad over 6 feet long. I wasn't aware when I bought the original, that it was a diff version. But a pair of $2 rs485 to TTL adapters fixed that up perfectly once they were jumper-ed as rx only. But I took the original apart to see what was wrong a few months back, but it looked ok internally, so put it back together, which fixed it and its still working fine. But on the back of that motor, its being spun at least 2x its rated max speed. Pretty decent for a $21 encoder. > https://youtu.be/kV4vqhOgjcc > > > Regards > > Andrew > > On Mon, Dec 28, 2020, 1:00 PM andrew beck <[email protected]> wrote: > > Hey everyone just read all the replies. > > > > Definitely food for thought. > > > > Andy I currently do almost exactly what you do with the e stop in my > > mill. > > > > I'll do something similar with the enables tying in a relay to > > bypass them with the e stop and then letting linuxcnc know about it > > > > On Sun, Dec 27, 2020, 3:17 AM Gene Heskett <[email protected]> wrote: > >> On Saturday 26 December 2020 04:57:38 andrew beck wrote: > >> > hey everyone > >> > > >> > just for your interest here is a cnc lathe I am retrofitting here > >> > in NZ > >> > > >> > link to video on youtube > >> > <https://www.youtube.com/watch?v=TphcwK45zyc> > >> > > >> > still got a whole lot of work and need to sort out analog servo > >> > drive stuff tomorrow but thought I would send a email anyway > >> > > >> > also what do people do for E stop circuits with analog systems? I > >> > have only used a step direction system before this > >> > > >> > the servo drive has a "servo on input) that allows power to > >> > motor. I think the enable input from 7i77 should trigger this on > >> > and off. I want my big estop to also cut power too though so > >> > that I am not relying on software as that is not safe. current > >> > plan is to just put a relay in the servo enable circuit from 7i77 > >> > to servo drive. which gets cut by the Estop switch circuit. > >> > seems simple enough > >> > > >> > would love any ideas though > >> > > >> > and any things to watch out for. > >> > > >> > I know about checking encoder direction first and leaving motors > >> > on bench at first and all that sort of stuff. I will just take > >> > it easy > >> > > >> > regards > >> > >> Wow, Andrew. That is a lot more machine than anything I've got. > >> And separate e-stop circuits are something that I have been lacking > >> in doing. I have tended to make all that stuff as slaves to the > >> motion enable signal, controlled by the F2 key on the keyboard, > >> which in turn controls all other machine power, and has worked > >> flawlessly. But it is not a guard against a computer crash which > >> really needs an independent way to shut down the power. I've > >> considered a multipole relay which would be in series with the > >> enable signal, which could shut off all power to the machine > >> independent of the computer, and I bought several of the latching > >> switches from the mini-lathe parts list, but haven't found that > >> famous round tuit yet. But I think that idea has the best merit, > >> bypassing, and over-riding anything the computer might decide to > >> make the machine do. > >> > >> I did change the motors and drives on my Sheldon this fall, from > >> normal steppers to the newer 3 phase stepper/servo's and I am very > >> happy with the results of feeding the FAULT signals back into > >> LinuxCNC, effectively toggling the F2 button there. I traded a 1600 > >> oz/in nema 34 on the z screw for a 3NM nema-23, as much because the > >> 1600 shook tools off the whole machine, doubling my Z speed rapids, > >> and pulled a 270 oz/in nema-23 off the X in favor of a 2NM version > >> of the 3 phase drive. The whole machine now can move 2-3x faster, > >> and moves like casper the ghost. > >> > >> I haven't tested the X because the screw is so small and I might > >> damage it with the 2NM motor geared 2/1, but I can now mount a > >> carbide tool, position it to hit a chuck jaw, and drive it into the > >> chuck jaw at 2 ipm, from the Z, it detects the contact and faults, > >> with the Z bouncing back from jaw contact by about .010" as the > >> power goes off, without damage to the chuck jaw or to the carbide > >> chip in the tool. With a 25mm Z screw, that 1600 would have crushed > >> the chip and bent the tool if it were pinned to the carriage, which > >> it is not. > >> > >> That to me was worth the nominally $250 to swap the motors. And > >> although I've been warned that some have noted the stepper servos > >> can lose counts, the 3 phase drives I have used so far haven't lost > >> a step. I'd submit that those reporting such as problem have noise > >> in their systems or are pushing the step timing. > >> > >> Anyway, that's my take on it, but if anyone has a good pattern to > >> make round tuits that isn't already copyrighted, I'll make some for > >> my friends as several have lamented they haven't found one yet. > >> > >> That would be a piece of cake for my 6040 with its new 2.2kw > >> spindle. > >> > >> Now, lets all hope that 2021 will be a better year, 2020 was/is the > >> pits. > >> > >> > Andrew > >> > > >> > _______________________________________________ > >> > 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) > >> 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-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 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-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
