On Tuesday 25 September 2012 23:23:36 Igor Chudov did opine: > I have a routine that lets me mill a deep circle in several passes, > typically to cutout circles from plates. > > Something strange is going on and the resulting shape is not exactly > round. It can be best described as a circle with humps. > > The routine is below. It is basically a while loop, milling > progressively deeper until Z reaches the required depth. Every loop > consists of two half circles milled helically, with the end mill going > down along a spiral. > > Any idea why the shape may not end up being circular? > > Thanks > > Routine attached. > > (Copyright - Igor Chudov, released under GNU Public License V3) > > O<circulargroove> sub (circular groove, good for milling through holes > too) #<xc> = #1 (X center) > #<yc> = #2 (Y center) > #<safez> = #3 (safe height) > #<depth> = #4 (depth of milling) > #<radius> = #5 (outside radius) > #<milld> = #6 (end mill diameter) > #<frate> = #7 (feed rate) > #<zstep> = #8 (z step, per circle, optional) > > O<if> if [ #<frate> NE 0 ] > F#<frate> > O<if> endif > > O<if> if [ #<zstep> EQ 0 ] > #<zstep> = [#<milld>/3] > O<if> endif > > #<z> = #<safez> > #<r> = [#<radius> - #<milld>/2] > > G0 Z#<safez> > G4 P0 > G0 X[#<xc> + #<r>] Y#<yc> > > O<loop> while [ 1 ] > > O<if> if [ #<z> - #<zstep> LT #<depth>] > #<zstep> = [#<z> - #<depth>] > O<if> endif > > G2 X[#<xc> - #<r>] Y#<yc> Z[#<z> - #<zstep>/2] R#<r> > G2 X[#<xc> + #<r>] Y#<yc> Z[#<z> - #<zstep>] R#<r> > > #<z> = [#<z> - #<zstep>] > > O<if> if [ #<z> LE #<depth> ] > O<loop> break > O<if> endif > > O<loop> endwhile > > G2 X[#<xc> - #<r>] Y#<yc> R#<r> > G2 X[#<xc> + #<r>] Y#<yc> R#<r> > > G0 Z#<safez> > > O<circulargroove> endsub > > M2
The first thing I'd check would be uncompensated backlash. Then it would go to damaged screws, like a highly used area wobbled out. Third would be scaling error on one axis, but thats fairly easy to check. 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) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! A penny saved has not been spent. ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
