The book "CNC Programming" by Peter Smid is frequently used for learning complicated CNC programming methods. It contains an easier to understand description of the Fanuc style cycles. Fanuc has implemented two versions, one called a "one block" format and the other called "double block" format. Both utilize the U and W words as you propose, so the issue of EMC handling those words differently in a G71 cycle still exists.
This book also describes a G72 cycle for use in facing cuts that is very similar to the G71 cycle. Regards, Steve Stallings > -----Original Message----- > From: Daniel Goller [mailto:[email protected]] > Sent: Tuesday, June 08, 2010 9:18 PM > To: [email protected] > Subject: [Emc-users] Preferred syntax of G71 > > I am planning on (slowly) implementing a G71 roughing cycle for EMC2. > > The syntax varies between manufacturers and i would like to > use this post to setup a syntax everyone can agree on. > I think the goal is easy, it has to work well within EMC2's > gcode and variable use, some may hope it's just like "their" > G71, but that might not happen, if the result is just like > you are used to, you are lucky :). > > We need a way to specify: > > Depth of cut: Word proposal: D > Retract: Word proposal: R > Stock allowance in X: Word proposal: U > Stock allowance in Z: Word proposal: W > First line of shape to rough: Word: P > Last line of shape to rough: Word: Q > > You may have followed link [1] already and wonder why i > started out saying that people probably won't get what they > are used to and now the proposal above is identical to Haas' > G71. I was already told using U and W could be a problem > since U and W are already in use for second turret motion of X and Z. > (Proposed) Example: > > G00 Z.1 > G00 X7. > G71 P10 Q20 D.250 U.02 W.005 R.050 F.010 N10 G0 X5. > N20 G1 Z-8. > G00 Z.1 > G28 X0. > G28 Z0. > > The above example would position to Z.1 and X7., the start > point from which to run the canned cycle. X7-X5 > 0 means we > are cutting an OD, we cut a stock of 7" down to 5.02" , > 7.995" long in .250" radial depth, retracting at the end of > the pass at 45deg. (think Z=Z+R > X=X+2*R) > (I am aware that this simplest use example could easily be > done in a o word loop, i've done it, it's a syntax example) > > If there is no way in EMC to differentiate between the use of > U and W for motion and U and W for a canned cycle setup, we > need other words to use in place of U and W, and to be > honest, the words used don't actually matter as long as they > don't interfere with anything else and are documented so it's > easy for new users to adapt to use this G71. > > The link [2] i think nicely illustrates the benefit of using > a simple canned cycle for roughing vs handcoding this line by > line. (I cheated and asked our CAM software to post without > canned cycles for the examples on that link.) Especially when > moving the same code between different size machines that can > deal with different depths of cut. No need to maintain > separate programs for different machines either. > I would like to propose a single line for a G71 like the way > Haas sets them up [1], unlike the double line G71 (some) > Fanuc controllers use [2]. > My current goal is to implement G71 in a way that it will not > consider undercuts, it is the safer of the two variants of > G71 cycles. And still a most useful tool. > > I am looking forward to hear your suggestions, > > Daniel > > [1] http://wiki.linuxcnc.org/emcinfo.pl?HaasRoughingFinishing > > [2] http://wiki.linuxcnc.org/emcinfo.pl?FanucRoughingCycleExamples > > -------------------------------------------------------------- > ---------------- > ThinkGeek and WIRED's GeekDad team up for the Ultimate > GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky > parental unit. See the prize list and enter to win: > http://p.sf.net/sfu/thinkgeek-promo > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
