On Friday 14 December 2007, Drew Rogge wrote: >I've been using TurboCNC off an on for a few years now and >last night I ran into a problem with my gecko servo driver >faulting out. I think the problem is that I was running a >low feedrate, 2.25 IPM, and have a lot of backlash comp- >ensation, .005", configured. I'm pretty sure that the >drive was faulting when the X axis switched feed directions >and TCNC would issue a bunch of pulses to take out the back- >lash. I seem to recall that TCNC doesn't use any kind of an >acceleration curve or anything for these moves. > >So any way, do people feel that EMC2 does a good job of >dealing with large amounts of backlash? Has anyone had a >problem with drives faulting during backlash comp? > >Thanks, >Drew
I'm not a coder, just a user so I could be wrong here. I believe emc now uses the MAXACCEL & MAXVEL (I think that's the correct names) variables to profile the backlash moves since version 2.0.0 I believe, and I have used backlash settings up to 17 thou in my Z axis settings without a problem other than the head still rocks and a curve cut that involves a direction reversal of the Z at the top of the curve still leaves a visible artifact in the finish. I've since rebuilt my Z drive from scratch and now use about 2 thou of backlash comp. The drive is now in front of the post and much much stiffer. IMO EMC is doing a great job of handling that now. I recently cut some pockets for ball bearings that took some tweeking of the x & y backlash settings I had previously guessed at from watching a dial indicator, and by the time I reached the finished size of the pocket, the error from a perfect circle was not detectable by my cheap dial indicators, one mechanical, one digital. Driving the bearings in and back out to polish the high spots generally showed a pretty random contact pattern, and my new z axis drive is happy, that's where the bearing pockets were going to be used. Yeah I know, a micromill is a sows ear, but its what I could afford at the time. It doesn't much resemble the catalog picture now. :) -- 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) Please help keep the world clean: others may wish to use it. ------------------------------------------------------------------------- SF.Net email is sponsored by: Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
