Stuart Stevenson wrote: > Gentlemen, > I tried homing the machine using the new cycle available. I have > two marks on the machine. One mark on the moving element and one mark > on the stationary element. I position the machine with the marks in > alignment and push the home button. The axis moves .010/.020 and the > axis homes as expected. I then moved the machine to misalign the marks > by .030 in the direction opposite my homing direction. The machine > homed in a different spot about .010 from when I pushed the home > button. I moved the axis .030 again in the direction opposite my > homing direction. The machine homed in another spot about .010 from > where I pushed the home button. I took a cover off the side of the > axis drive to verify how much the motor moves per inch. The axis moves > .200 per revolution of the motor. The homing doesn't seem correct. I > believe it should home in a maximum of 6 positions per inch. (Just got back from a trip to a very wet Texas.)
I did quite a bit of homing on my minimill at the CNC workshop. I had a setup on the machine doing threading, and if the X axis was not homing repeatably, I would have known about it. I will update to the latest EMC2 from CVS and check it on the Bridgeport, which more closely resembles your setup. If it is homing to the index pulse, there should be a noticable click from the servos when the encoder count goes to zero. I am using the home sequence where the search for index is in the same direction as the search for home switch, ie. it goes past the point where the home switch trips to find the index pulse. I had some trouble getting other home sequences to work correctly, but there were problems in the driver at that time. You might try that homing sequence to see if it is more repeatable. I can't figure out how the homing could be so erratic if it is really seeking the index pulse to qualify the final home position. (Even microswitches should be more repeatable than your results.) Or, maybe there is a special case when you are homing from very close to the home position. I will try a number of things to see if this reproduces here, but I don't think it will. I haven't done a dial indicator test here on the Bridgeport, but I just have a feeling it will home repeatably. I'll let you know when I get a scientific test done. Jon ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
