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 ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Register now and save $200. Hurry, offer ends at 11:59 p.m., Monday, April 7! Use priority code J8TLD2. 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
