re 1 - I guess feedrate modulation could work through feed override? re 2 - the simple solution is to make the reverse feed work only within the last two moves (backup doesnt work at the very start of a motion - to where?), and also the move must be longer than wire diameter. are these realistic restrictions?
re 3 - that's almost like a probe; the more I think of it you could probably do primitive EDM with probing moves (straight only); I'd probably latch the wire breakage point like in the probe run, plus a line number; the run-from-line would have to modify the current move to rapid to breakage point and feed from there re code - it's probably better just to have pin detection (backup and wire-ok) plus position latching in motion, and flush the interpolators on backup == 1; and have the rest handled in task -m Am 06.11.2011 um 17:44 schrieb Steve Stallings: > Some things to consider regarding wire EDM: > > 1) Feed rates are very slow, so feedhold can > be "almost" instant. Feedrate is modulated > by the cutting process much like torch height > is modulated in plasma cutting. > > 2) Reverse feed, for the purpose of controlling > the cut, will be less than the wire diameter. > This is used to clear shorts, and then resume > cutting. This is typically automatic. > > 3) Rethreading when the wire breaks is a consideration. > This may require something like: > a)jog to clear spot to rethread, might be all > the way back to the start in some cases > b)run from here - to reenter the path > c)run rapid to here - to get back to where the > wire broke > d)resume cutting > > 4) A wire EDM with four axes will need to be able > to interpolate an arc simultaneously in XY and UV. > Sometimes this is relegated to CAM, but this results > in huge files. > > Steve Stallings > > >> -----Original Message----- >> From: Michael Haberler [mailto:[email protected]] >> Sent: Sunday, November 06, 2011 11:10 AM >> To: EMC developers >> Subject: [Emc-developers] EDM: motion question - backing up moves >> >> out of todays IRC discussion - making motion usable for EDM >> (maybe other things like swarf removal): >> >> the idea came up for a motion pin 'backup' which would stop >> and revert the current move to its starting point; possibly >> several moves with a window. >> >> would the following approach be realistic: >> >> - a EMCMOT_SET_LINE or EMCMOT_SET_CIRCLE command would be >> added to the motion window of a given max window size (maybe >> just 1 to start with) >> - when during a coordinated move 'backup == 1' is seen: >> >> 1. motion would do the equivalent of feed hold but also flush >> the joint interpolators >> 2. looking at the current command, it would computer reverse >> kins from joint position, and generate a reverse move to the >> current commands starting postion, at feedrate (possibly >> corrected by a back-feedrate factor) >> 3. step back through the motion window until window size >> reached and stop until 'backup == 0' >> 4. from then replay the motion commands in window in forward >> direction until window exhausted >> - then start fetching motion commands again >> >> making any sense? >> >> what's unclear to me: >> >> - in 2, how to make sure joint motion has stopped - doing the >> feedhold equivalent doesnt necessarily imply instantaneous stop? >> - what the best place for keeping the motion window is: >> -- this could be either within motion, independent of task >> -- or within task, which would keep a window and possible >> could be told by a motion return code to 'step back in the >> window' which I think is more elegant; also error detection >> (eg steps which cant be (easily) reverted) would be at that level >> >> just a sunday afternoon idea >> >> -m >> -------------------------------------------------------------- >> ---------------- >> RSA(R) Conference 2012 >> Save $700 by Nov 18 >> Register now >> http://p.sf.net/sfu/rsa-sfdev2dev1 >> _______________________________________________ >> Emc-developers mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/emc-developers >> > > > ------------------------------------------------------------------------------ > RSA(R) Conference 2012 > Save $700 by Nov 18 > Register now > http://p.sf.net/sfu/rsa-sfdev2dev1 > _______________________________________________ > Emc-developers mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-developers ------------------------------------------------------------------------------ RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
