[M.RISHIKESH]

Dear Sirs

We have got a Nigata HMC with FS18i-MB. X axis is running with motor encoder (Linear scale for closed loop was bypassed about a year back)

Since last 3 days , we are finding that X axis is moving little excess that means, if we move X axis by 100 microns, it actually moves by 120microns and this is also not consistent that means sometimes it is consistently excess by say 20 microns and suddenly it exceeds 20 microns even

We tried in different places of Axes just to isolate issue related to LM Guide/Ballscrew in a particular area still readings are not consistent and it is always excess of what is commanded

No loose connection found in encoder and its cable (Motor and Drive end)

Please advice

[ifixcnc]

Motor to ballscrew coupling, ballscrew thrust bearings can cause that.
Best of luck.

[M.RISHIKESH]

Motor to ballscrew coupling, ballscrew thrust bearings can cause that.
Best of luck.

Sir

Thanks for your reply. Actually we have retightened Jib screw between Table and LM Guides of X axis, now found ok

We were wondering why we were not getting any error like excess error (Moving)/Stop although paramters for Excess Error(Moving) and Stop are intact as we received the machine about 7 years back , we have never changed these parameters- Please advice

Warm Regards,

[ifixcnc]

With Linear scale for closed loop was bypassed, the only feedback you have is from the encoder on the end of the motor. It can not see what the slide is doing, That is what the scale is for.