On Sunday, March 18, 2012 10:56:07 AM Michael Haberler did opine: > Am 18.03.2012 um 13:36 schrieb Tony Zampini: > > ... > > > On a more general note, being able to "touch off after a tool change" > > seems to me to be a necessary function for any and every milling > > operation. Why doesn't EMC2 have this feature built-in? Or, to put it > > another way, how are users of EMC2 currently determining the new z > > offset after changing tools, assuming they don't use a probing > > feature? Just curious.
See below. > please see the example in > http://git.linuxcnc.org/gitweb?p=emc2.git;a=tree;f=configs/sim/remap/man > ual-toolchange-with-tool-length-switch;h=8c716f10d20a9f0722de83dda3fb393 > 087d94270;hb=10d8caf753ab0269f882d83b59a6c76e2e3ae28d > > this can easily be adapted to other forms of touchoff > > -m I am not aware to a method that doesn't at some point make use of the G38.2 function, which means there MUST be a probe of the tool. In my case, doing pcb work using eagle & pcb2gcode, I wrote some routines that assume the probing pin is connected to the pcb itself. In my case, the use of the routines requires that calls to the probe function be manually edited into the pcb-gcode output to command a move to a location that clears the work space for the tool change, and after each tool change call the subroutine to establish the offset. As I tend to run with rather leasurely accelerations, my probes are done relatively slowly so the tool doesn't overshoot and mark up the workpiece, so each probe adds about a minute to the production time. I also added a bit of a fudge factor so the 'etching' depth can be controlled without having to rerun pcb-gcode and then reinstall this stuff by editing in everything all over again. At my web page in the sig, add /Genes-os9-stf/eagle to the path and you can download the 3 files I use. tedautoz.ngc (tOPeTCHdRILL.ngc) bedautoz.ngc (bOTTOMeTCHdRILL.ngc) tholefinder.ngc PCB-Pallat.JPG tholefnder.ngc is written to use a short piece of tubing let into the pallet that holds the pcb for etching, and the offsets it develops as it runs set the left-right offsets in G55 and G56 modes so the top etch, top drill, matches up with the bottom etch and bottom drill files. PCB- Pallat.JPG shows fuzzily, what my pallet for that first board looks like. The grayer area in the center has been relieved another 25 thou so any machining burrs left from the etching and drilling of the first side do not prop the board up and mess up the bottom side by etching too deeply. tholefinder.ngc will of course need editing so that what it discovers will work for the pcb carrying pallet you'll need to make. I made mine from some 1/2" micarta I bought a couple slabs of from Highland Hardware in Hotlanta, intending to make zero clearance inserts for my BT-3000 Ryobi table saw, something that saw is very badly in need of since the plastic casting they sell comes out of the box sitting 50 thou too low all over, and over .1" low at the top center of the blade. I made 2 zero clearance inserts, and haven't damaged the first one yet. Piece of crap factory plastic I won't every buy again. The micarta works great. 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> Hanson's Treatment of Time: There are never enough hours in a day, but always too many days before Saturday. ------------------------------------------------------------------------------ This SF email is sponsosred by: Try Windows Azure free for 90 days Click Here http://p.sf.net/sfu/sfd2d-msazure _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
