On Thursday 24 April 2008, Gene Heskett wrote: >On Thursday 24 April 2008, [EMAIL PROTECTED] wrote: >>> Gene Heskett wrote: >>>> A bit rough on an obvious newbie, John. In this case, and reading >>>> between the >>>> lines, I'm guessing that the terminology and format of the questions >>>> stepconf >>>> is asking are in effect, swahili to the OP, they are quite concise >>>> because of >>>> the gui's limits. When I ran it the first time, there were several items >>>> I >>>> didn't get right as the wording was somewhat ambiguous. >>> >>> I'll admit I was a bit rough, and I apologize. But... >>> >>>> He will in time learn, if we are willing to help, but first we need to >>>> know >>>> which question the OP is attempting to derive the answer to. >>> >>> EXACTLY! >>> >>> He didn't say "I've done steps 1, 2, and 3, but I'm stuck on step 4". >>> He said "give me the numbers". And when John Thornton asked him "Which >>> number", he said "all of them". >>> >>> I am more than willing to try to help. But the person asking for help >>> has to put in some effort too. >>> >>> Regards, >>> >>> John Kasunich >>> >>> ------------------------------------------------------------------------- >>> This SF.net email is sponsored by the 2008 JavaOne(SM) Conference >>> Don't miss this year's exciting event. There's still time to save $100. >>> Use priority code J8TL2D2. >>> http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/ja >>>v aone _______________________________________________ >>> Emc-users mailing list >>> [email protected] >>> https://lists.sourceforge.net/lists/listinfo/emc-users >> >>I've tried putting numbers in like 400 steps per rev .5 micro stepping >>and the machine only travels half the distance that you tell it to. Also >>the Y and Z axes run backwords and I can't figure out where to go from >>here. any help would be greatly appreciated. > >If they are running backwards, you can use a minus sign in front of the > scale value, or you can interchange the ends of one winding only either at > the motor or at the terminals of the driver package. > >I don't recall now if you stated what driver package is used, and I'm not >familiar enough with the Sherline to know that. If they were xylotex > drives, they are setup to default to 8 microsteps, others may be more, or > less. > >This all goes into figuring out the scale value to be used, and it sounds > like the driver is set for twice as many microsteps as the software is. > The more microsteps, the smoother the motor will move, particularly in its > self resonant range, it can make a huge diff in the working torque at those > speeds, in favor of the microstepped motor. > > >Here are some 'rules of thumb' >1. 99% of the stepper motors used for this need 200 full steps for one >revolution. > >2. If the driver microsteps the motor by a factor of 8, then the motor will >need to see 200*8=1600 steps for a full turn. Scale this according to the >number of microsteps your driver is doing. > >3. If the motors are directly driving the screws, and I'm reasonably sure >Sherline is, then this 1600 needs to be multiplied by the number of threads >per _your_ unit of measure. Eg, if you are running in inches, and the >leadscrew in the mill is a 20 tpi screw, then 1200x20=32000 for the scale. > Damn typu's! 1600*20=32000 obviously.
>4. Then for MAXVEL, until you know what the machine can actually do, pick >something safe like maybe 3, and set a somewhat lower limit for MAXACCEL, 2, >2.5 maybe. Exercise that using the stepconf test facility by giving it a >range over which it is to move the motor, say 2" each way, and hit run. If >it moves ok, but seems slow and you can hear the motors slowing down and >winding up to speed at each end of the moves, increase MAXACCEL and MAXVEL > by half a point & retry. At some point the motor may freeze and buzz or > sing, if the move is well under way when this occurs, reduce MAXVEL by a > full point so you have a safety margin under load, but if it does this just > as its reversing, then MAXACCEL is too high, reduce it a full point, and > move on to do the same thing with the next axis. > >Practice may find that these will still need to be tweaked one way or the >other, but that should get you at least playing in the ballpark. > >I hope this helps. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Hedonist for hire... no job too easy! ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
