Jeff Epler wrote: > It may be useful to refer to the docs, which I believe are up to date > http://linuxcnc.org/docs/devel/html/gcode_main.html#sec:G33,-G33.1:-Spindle-Synchronized > .. but perhaps this conversation can help improve the documentation. > > On Mon, Oct 15, 2007 at 11:33:27AM -0700, Kirk Wallace wrote: > >>- Can a K be applied to each axis? Such as G33 z1.0 k0.050 x0.100 >>k0.010. I suppose, I could just try it and see what happens. > > > No, there can be only one K-word. The K-word gives the distance moved > for each revolution of the spindle. For instance, if you are at X=0 Z=0 > and command > G33 X3 Z4 K.1 > then the move will be on a sloped line with a total length of 5 > (sqrt(3*3 + 4.4)). During that time, the spindle will turn 5/.1 = 50 > times. The first turn will be 1/50th of the total distance, which means > that the machine will reach X.06 Z.08 at that time. What? The pitch of the thread is relative to the actual line of movement, not the Z axis alone? I looked this up in the EIA-274-D, and it is a bit hard to understand, but they say " Lead in decimal inches (mm) per revolution parallel to the PRIMARY axes shall be addressed by I, J or K, respectively."
It isn't too clear what the "primary axes" means, but may me explained by what I have below. Looking at the ES274/NGC work in progress document from NIST, which was actually an Allen-Bradley manual that was hacked over with pencil, their definition of the G33 shows E or F was the lead specification for the axis with the largest distance to travel. E was in threads per unit, F was in units per thread. Mutually exclusive, of course. The K word is used in G34 to specify the change in thread lead per rev. > This little snippet from the threading program I've been using to test threading seems to work that way, too : g1x[#1 - #6] g33z[.1 + #7]k#4 (stay synchronized and exit at 45 degrees) g33x[.1 + #1 - #6]z#7k[sqrt[2]*[#4]] g0x[#1 + .2] I have no idea if this is common G-code practice, but I have not seen it before. Is there any definitive place we can check how most G-code interpretations handle this? (I'm awfully sure that standard practice, where the major movement is in the Z axis, have the pitch specification apply exclusively to the Z axis. (it gets harder to define at 45 degrees). Doing some googling, I didn't find a whole lot, but one note in CNCZone shows code for a Mitubishi control where F is the lead on a G76 command. Wayne Hill shows some code using G33, also F is the lead. He doesn't say what control that is for. DeskCNC uses P to set the "thread pitch", without defining it, but usually thread pitches are calculated directly along the thread axis. TurboCNC uses I, J, K to specify the lead for axes X, Y Z, respectively. It apparently allows you to specify a lead for more than one axis at a time, I can't imagine how they deal with that. They say "the lead and distance should work out to an equal number of revolutions for each. Machinery's Handbook was about as vague as the EIA-274-D standard, because they must have used that as their reference. Jon ------------------------------------------------------------------------- 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
