I am trying to do what appears to be a simple operation in g code but it seems to be over my head. here's the setup: I am using xyza with rotary axis parallel to X. I am using an endmill in the spindle to cut a square thread in a round bar in the chuck of the a axis. to cut a 5 pitch thread of 2 inch length the primary command line is G1 X2 A3600. There is obviously more to the program(multiple cuts with incremented Z etc) but this is the basic command.
Here is the problem: When I finish the 10 revolutions along the 2 inch length I need to extract the tool and go back to where I started for the next cut. I can use G0 to extract the tool and bring it back to the beginning of the cut...But... If I use G0 A0 the darned thing sits there and "unwinds" the A axis 10 turns all the way back to 0 degrees. Since I went an integral multiplier of 360 degrees it is already sitting on "0" degrees of the part but EMC wants to "unwind" it back to 0 which is where it already is. What I would like: I would like to tell the controller "yeah, I know you think you are sitting on 3600 degrees but I'm telling you to forget that and from now 'til I tell you otherwise you are at 0 degrees which is home." Now I can increment the cut depth and repeat the process till the cut is done. I think what I am looking for is a way to "home" the axis with no movement. I tried G92 and G28 but they really don't Home the axis, they just store an offset in the .var file and offset the axis by that much on any move. The problem with that is that those offsets stay in the var file and when you bring up the controller the next time they are still there. So now every time I start EMC I have to remember to open the .var file and clean up all the junk BEFORE I start EMC. I know I could just increment the A command each time ...A3600 on pass one A7200 on pass two A9800 on pass three etc. but that seems like a workaround and besides when I finish the job I will have to "UNWIND" 30 revolutions or shut down EMC and start over. Bottom Line: Is there some G command that works like the "HOME" button in AXIS or TKEMC that simply "makes the present position HOME" ???? Without storing offsets in the .var file I know I am going to be embarrassed by how simple the solution is but it has evaded me for the last 3 days so I am asking for help. Thanks, Cecil ------------------------------------------------------------------------- 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
