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
