On Wednesday 10 October 2007, Chris Radek wrote: >On Wed, Oct 10, 2007 at 08:22:16AM -0400, Gene Heskett wrote: >> Which probably explains why I've never been able to make the I,J format >> work reliably here Jon. I'd always figured 3 places was close enough for >> the girls I go with. :) > >There's some good advice in the "Best Practices" section of the >manual: > >http://www.linuxcnc.org/docs/html/gcode/main/index.html#SECTION0080000000000 >0000000 > >It mentions precision for the arc checks. Also it says to prefer >center format (IJK) arcs. This is contrary to Jon's advice to use R >format. Jon is right that R format is less likely to give an error. >However, because of this it is also less likely to give you the arc >you want, especially if your arc is nearly a semicircle or nearly a >circle. > >IJK format, once you give correct precision for the points, is the >best way to exactly specify the arc you want (even if it's a full >circle). > Well, at the time I was carving bearing seats in 3.5" square alu blocks about 1.25 thick, and any inaccuracies in the math were totally hidden in the backlash and other mechanical errors in my micromill. But I did eventually get the job done well enough they were a push fit, and since the load was axial & the bearing was made for axial loading, it all worked out ok. Its in the z-axis of that mill now, and more accurate by a factor of 10 or so.
I did that in 90 degree segments, using the R word. >Chris > >------------------------------------------------------------------------- >This SF.net email is sponsored by: Splunk Inc. >Still grepping through log files to find problems? Stop. >Now Search log events and configuration files using AJAX and a browser. >Download your FREE copy of Splunk now >> http://get.splunk.com/ >_______________________________________________ >Emc-users mailing list >[email protected] >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) Martin was probably ripping them off. That's some family, isn't it? Incest, prostitution, fanaticism, software. -- Charles Willeford, "Miami Blues" ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
