Emory, I changed the jumpers on my HobbyCNC board.
I then recalculated the number of steps to move one unit (one inch or one millimeter) then adjusted the INPUT_SCALE value in the EMC2 ini file to that amount. Basically going from full stepping to 1/4 stepping will quadruple the value for INPUT_SCALE, but if your lead screws are in inches and you are using EMC2 in mm, or vice versa, I would recalculate the INPUT_SCALE value from scratch to avoid any rounding problems. Andy Emory Smith wrote: > 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)" >> <emc-users@lists.sourceforge.net> >> >>> 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 >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > > > -- 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
