Ron Ginger wrote: >>I am a "servo bigot", and just don't want to do anything like >>machining metal while "flying blind", which is how I think of >>stepper systems. >> >>Jon > > > I cant let this pass without a comment. As someone said earlier this is > 'holy war #1' in the CNC hobby. > > It is a fact, not disputable, that thousands, maybe 10's of thousands, > of large, even Bridgeport machines use steppers. They make parts every > day, day after day and never loose a step. Yup, that's why I specifically CHOSE the word "bigot", to imply an element of non-rationality to it.
But, losing steps is not the ONLY reason for servos. There is also the speed range vs. resolution dilemma. If you want more resolution, you need to gear down the stepper. But, steppers are strongest at lower speeds, so gearing down cuts the high end speed. I have encoder resolution of 50 uInch on my Bridgeport, but can go to 120 IPM if needed. (I usually don't, as I tend to cause crashes.) This would be hard to do with stepper motors. Another thing is that axis alignment is preserved when you hit Estop or crash. That generally isn't the case with a stepper system. Jon ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
