Excel 810/ Fanuc OM-C Work Offset Discrepancy

Hello,

I have a 1994 Excel 810 running a Fanuc OM-C controller. I am having an issue where if I drill a hole(doesn't matter what size drill) The hole will be .010" off in the Y-axis from the called out position in the program. BUT if I do a milling operation or interpolate a hole they will be in the correct position. I have no idea what to do about this. I have checked the gibs in the machine and they are all within tolerance as far as I know (There is no good information for this machine that I have found) I have checked the ball screws for backlash and I only have about +/- .001 at best in all axis. The way we have dealt with this usually is to put a positive .010" in the work shift if we are only doing drilling operations but if there is both drilling and milling then we have position accuracy problems. I appreciate any help I can get.

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Originally Posted by Toms_Electric_Company

Hello,

I have a 1994 Excel 810 running a Fanuc OM-C controller. I am having an issue where if I drill a hole(doesn't matter what size drill) The hole will be .010" off in the Y-axis from the called out position in the program. BUT if I do a milling operation or interpolate a hole they will be in the correct position. I have no idea what to do about this. I have checked the gibs in the machine and they are all within tolerance as far as I know (There is no good information for this machine that I have found) I have checked the ball screws for backlash and I only have about +/- .001 at best in all axis. The way we have dealt with this usually is to put a positive .010" in the work shift if we are only doing drilling operations but if there is both drilling and milling then we have position accuracy problems. I appreciate any help I can get.

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Try using G53 block by block to cancel X and Y axis offsets. Drilling only needs a tool length.

Check X and Y axis reference points to the table centre zero point using centre bung or bore.

How about a little history of the machine and your ownership of it.

Are you brand new to running this machine?

Was it working before and now is acting up with the 10 thou discrepancy?

Any crashes you know of?

Show some of the G code being used.

@the_gentle giant and @servtech I posted this question over at CNCZone as well and it was suggested that I sweep/tram the head. I did and found that I had .005 variance on a 12" dia circle. I recently tightened the gibs that would control the tip of the Z head casting and found that they were both excessively worn and one was completely backed off to the point of not touching. I also happened to throw a level on the table as well and the machine is not level either. I believe this all explains my issues. We don't have time to fix this problem but to finally know what is wrong is a huge relief. Thank you so much for the help.