I have a G540 that would not step slower than 150 Hz on the Y axis driver. 3 other drivers stepped as slowly as I cared to try. I originally had 2.6us step pulses obeying the data sheet requirement of 2us. Increasing pulse length to more than 5us fixed (or masked if you wish) this issue. The tool to use is "setp parport.0.reset-time 5000"
/Lars > -----Original Message----- > From: Igor Chudov [mailto:ichu...@gmail.com] > Sent: den 15 juli 2011 21:44 > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] erratic behaviour at low feed rates > > I had the same issue with erratic behavior, turned out to be a bad > amplifier. I replaced it. > > > On Fri, Jul 15, 2011 at 2:08 PM, gene heskett <ghesk...@wdtv.com> > wrote: > > > On Friday, July 15, 2011 02:55:36 PM Andy Howell did opine: > > > > > On 07/15/2011 09:40 AM, gene heskett wrote: > > > > On Friday, July 15, 2011 10:37:53 AM Daniel Rogge did opine: > > > >> If you swap the X and Y drivers it will be fairly easy to > determine > > > >> whether the problem is with the driver (as Gene suspects) or > with > > > >> friction or mechanical linkages (as Jan suspects). If the > problem > > > >> stays on Y after swapping drivers, then your driver is absolved, > > > >> leaving only mechanical or step signal generation problems as > > > >> possibilities. You can distinguish between these last two by > only > > > >> swapping the control leads between drivers while leaving the > motor > > > >> leads hooked up as they are now. > > > >> > > > >> Rogge > > > > > > > > And in any event, please do not silently fix it, the OP should > post > > > > what the OP did so that we'll have better info to refer to the > next > > > > time it happens. > > > > > > All, > > > > > > Thanks for all your pointers. I swapped the X and Y > connectors at > > the > > > Geckodrive controller and the problem rotated 90 degrees. > > > > Andy: This is pretty solid evidence that it is indeed the gecko, you > moved > > the problem amplifier to the other motor. Call Gecko for the next > step. > > They may be able to repair it at nominal cost. > > > > > I measured > > > about 0.0067 inches of backlash on the Y axis. I can turn the Y > shaft > > > about 10~15 degree with no movement, which agrees with calculated > value > > > of 12.06 degrees of backlash. ( 5 TPI screw ) > > > > Yikes! This is huge for a ball screw and I would measure it full > length to > > see if it is consistent from one end of the screw to the other. If > it > > differs by more than half a thou over the length, the screw is worn > and I > > would replace the whole assembly. EMC has backlash comp you can > adjust per > > axis, but its only good if all cuts are dig cuts, climb cuts will > pull the > > table ahead of the screw very easily, and you will not see that with > a pen > > in the quill. IOW, replace the whole screw. Being used, I would > suspect it > > may have lots of hours doing the same part in the same fixture and > the > > screw is just plain worn out in the most used portion. In fact, I > would, > > based on that, map all 3 screws at 1 cm or 1/2" intervals. > > > > > The X axis backlash is about 0.0005. Both shafts turn freely when > power > > > is not applied. I've found some reference on the Hossmachine site > that > > > the ballnut backlash can be improved by putting in larger bearings. > > > I'll try that. > > > > > > There seems to be another problem though. I see the X and Y DRO > values > > > changing sometimes without any motor movement. This only happens at > low > > > speeds. > > > > > > I'll investigate that further after I address the backlash issue. > > > > > > Thank all for your help. I will let the list know how this was > resolved. > > > > > > Regards, > > > > > > Andy > > > > > > ------------------------------------------------------------------- > ----- > > > ------ AppSumo Presents a FREE Video for the SourceForge Community > by > > > Eric Ries, the creator of the Lean Startup Methodology on "Lean > Startup > > > Secrets Revealed." This video shows you how to validate your ideas, > > > optimize your ideas and identify your business strategy. > > > http://p.sf.net/sfu/appsumosfdev2dev > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > 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) > > To any truly impartial person, it would be obvious that I am always > right. > > > > > > --------------------------------------------------------------------- > --------- > > AppSumo Presents a FREE Video for the SourceForge Community by Eric > > Ries, the creator of the Lean Startup Methodology on "Lean Startup > > Secrets Revealed." This video shows you how to validate your ideas, > > optimize your ideas and identify your business strategy. > > http://p.sf.net/sfu/appsumosfdev2dev > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > ----------------------------------------------------------------------- > ------- > AppSumo Presents a FREE Video for the SourceForge Community by Eric > Ries, the creator of the Lean Startup Methodology on "Lean Startup > Secrets Revealed." This video shows you how to validate your ideas, > optimize your ideas and identify your business strategy. > http://p.sf.net/sfu/appsumosfdev2dev > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ 10 Tips for Better Web Security Learn 10 ways to better secure your business today. Topics covered include: Web security, SSL, hacker attacks & Denial of Service (DoS), private keys, security Microsoft Exchange, secure Instant Messaging, and much more. http://www.accelacomm.com/jaw/sfnl/114/51426210/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
