On Saturday 06 July 2019 08:55:54 andrew beck wrote: > Hey guys. > > I will post this on the forum also... > > So I'm just setting up my cnc mill with Mesa cards and step/dir > > Using 5i25 and 7i76. > I'm using that combo, twice. One is driving a 6040 quite well, the other is moving a Grizzly G0704
> Chinese servos are working well. > > But I just spent most of my Saturday chasing this funny stepgen joint > error. Copy/paste it here please. > I am wanting a resolution of at least. 0.005 mm. And I want at least > 12 m per min rapid speed as I'm retrofitting a high speed linear rail > machine. The ballscrews are 16 mm pitch. 16mm pitch and .005mm resolution? Multistart screws I assume. Thats asking for vanishingly small backlash, maybe even dual nuts loaded against each other with preload springs. And better screws than any I've used which are usually C7, the cheapest. > Does anyone know why I get a stepgen joint error? And also when > moving at high speed Linux cnc rapids to about 3 mm of the end and > then it slowly inches up the last little bit. > That sounds an awful lot like a way to low 'accel' someplace in that control chain, so it thinks it will take a long time to get stopped. But if thats the case it should also be accompanied by a long rather leasurely accel to top speed too. OTOH from 12m a minute, 3mm doesn't sound like too long a distance to get stopped. Your creep could be a PID windup too, too much IGain? Something you may have to observe with the halscope while driving it back and forth with a siggen module. That, despite the very poor bandwidth of the halscope, can be quite educational. Search back thru the archive for a mention of disconnecting one of the axis feedback signals, ISTR there was a problem that sounded like that which popped up about the time the joint/axis merge was done around a year ago. > I don't think its a big problem and I'll go ahead and bolt the motors > to the machine. But would appreciate some help from people. Also, if thats a gantry style machine, the y moves the whole gantry, which is the most massive part, and will often need a few percent less in the accel dept. HTH. May not, it seems my wet ram is getting less attentive. Too many birthdays or something like that. :( > Regards > > 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
