Andrew, What did you do to switch to 1/4 step mode. Was it within EMC or something on your controller? Is there a FAQ? I'd like to try that.
Thanks, Emory On Tue, Apr 8, 2008 at 8:08 PM, Andrew Ayre <[EMAIL PROTECTED]> wrote: > > John Kasunich wrote: > > Andrew Ayre wrote: > >> [EMAIL PROTECTED] wrote: > >>> --- [EMAIL PROTECTED] wrote: > >>> > >>> From: John Kasunich <[EMAIL PROTECTED]> > >>> To: "Enhanced Machine Controller (EMC)" <[email protected]> > >>> Subject: Re: [Emc-users] Newbie Help Needed - Losing Steps > >>> Date: Sun, 06 Apr 2008 19:46:09 -0400 > >>> > >>> Andrew Ayre wrote: > >>>> Hi, > >>>> > >>>> I have a gantry style machine with three axis. The X and Y axis have the > >>>> same motor and the same nut and lead screw on each). I am testing the > >>>> machine using manually entered commands into AXIS such as: > >>>> > >>>> G01 F80 X1 > >>>> G01 F80 X0 > >>>> > >>>> When manipulating one axis at a time (no cutting, just moving around) I > >>>> have found that I lose steps at different feed rates for each axis. > >>>> > >>>> X - lose steps at 148 ipm > >>>> Y - lose steps at 81 ipm > >>>> > >>> All those calculations are for theoretical limits to the step rate. But > >>> the reason you are losing steps is much less theoretical. You are > >>> probably running out of torque. When step motors go faster, the amount > >>> of torque that they can produce drops. When the load needs more torque > >>> than the motor can make, you lose steps. > >>> > >>> It does seem odd that the X can go faster than Y. X has to move more > >>> weight (I assume that X is the gantry, and Y moves a much smaller weight > >>> across the gantry). But something is making Y require more torque than > >>> X, so Y loses steps first. > >>> > >>> Regards, > >>> > >>> John Kasunich > >>> > >>> It looks to me like Andy is using full step motion. Probably what is > happening is that he's hitting resonant frequencies that are a bit different > for each axis. The extra weight of X might even work to advantage to help it > cross that zero torque spot. > >>> > >>> Rayh > >>> > >> Hi Ray, yes I'm using full stepping. My next step was to switch to 1/4 > >> or 1/8 microstepping. So could that actually help? I know that the > >> speeds overall will be reduced of course. > >> > > > > Micro-stepping will lower the theoretical speed, but as you've already > > calculated, the theoretical speed is pretty fast right now. On the good > > side, micro-stepping will mostly likely increase the torque somewhat, > > especially at certain speeds where full-stepping causes resonance and > > dramatically lowers torque. > > > > Regards, > > > > John Kasunich > > Update - I switched to 1/4 stepping mode. Movement is smoother and > quieter. The top speed of each axis is now limited by the speed of the > real time system on my PC, with no stalls. > > Thanks for the help. :) > > > Andy > > -- > Andy > PGP Key ID: 0xDC1B5864 > > ------------------------------------------------------------------------- > > 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 > -- Emory Smith [EMAIL PROTECTED] Website: http://stratcat50.googlepages.com Band: http://defoliants.googlepages.com Blog: http://stratcat50.blogspot.com/ ------------------------------------------------------------------------- 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
