Please Help, Fanuc 21 Alarm 411

[Dheimification]

Hey there guys,

I just purchased a Nardini Fast Trace with the Fanuc 21 control. I wired it up temporarily to be certain that it functions properly before I go nuts on setting it up (leveling, anchoring, and tool up). I ran it through a few cycles IE: Roughing, Grooving, Threading, Drilling.

I have aquired the alarm code 411 (details to follow as I left my manual at the shop), which I believe has to do with the Z servo either overshooting the target coordinate or being hindered from reaching the coordinate. Sorry that I dont know all the technical terms or data. The ball screw is in great condition as is the ways. so I dont think it is a block. I can rapid traverse the machine all day manually. It mainly only alarms out when running a drill cycle when the Z is moving from rapid out, back to rapid in. I have gotten it to also alarm out once while running a roughing cycle, and once during a thread cycle.

If anyone know of anything I should look into, please speak up. And please forgive me in advance for my lack of termonology and spelling LOL. Im hoping it is a simple parameter setting. I did call Fanuc and seem to be getting a run around

Thanks in advance, Doug

[memoryman]

this alarm is showing that the value set in parameter 1828 or 1829 has been exceeded.
Normally this is caused by the axis not moving at all, which could be caused by a mechanical problem or an electrical one such as blown fuse in axis drive, wiring issue etc.
When you reply, please indicate exactly which model 21 you have (a,b,c,ia,ib).

[Dheimification]

This is the Fanuc 20-T... Sorry now I feel stupid!

I was on the phone today with Fanuc and I was advised to disconnect the servo from the screw and re run where I was havving the alarm. I was advised to change parameter 2021 to a value of 0 when doing this. If I still got the alarm, It would be a servo or drive issue, If no alarm... then it was a mechanical problem ie: ball screw / nut, bearings and so on...

Well I got no alarm this time and I also noticed that there is a very small amount of slop between the screw and nut. Is it really this simple? The encoder is not attached to the ball screw. Its on the servo, so my question is How does the servo sense the slop in the nut?

Either way, looks like Im sending out the screw and nut for inspection and rebuild

[Dheimification]

Still need a hand here guys...

I had a company come up and remove the ball screw and nut. The balls were all replaced and the nut was packed. The screw and nut were professionally done and they installed new bearings all around. There is now most certianly no mechanical issue. Still have that damn alarm! Is there a chance that the previous owner changed some paramaters that need to be reset? The carrige hopps as well due to the servo compensating for somthing it seems comming off of the z rapid move. AHHH Im at my whits end!

[MysticMonkey]

run through this flow chart and see what you find

[sinha_nsit]

Does increasing the values in 1828/1829 a bit help?

[Dheimification]

Somewhat, but trhen I get a servo overload alarm.

I did lower the value of the Rapid move parameter from 7500 to 5000 and it helped a bit too. But now when running a semi finish or finish block, I get a 410 alarm at the end of the cycle.

The servo does not seem to ramp down properly and "hopps" at the end of the rapid return movment.