Okuma LNC8 OSP5020L Replaced X Axis Encoder and cannot adjust Zero Offset
Replaced encoder based on Youtube videos by Precision Zone "How to remove and replace encoder ER-FC-2048D," and "How to Adjust Soft Limits on Okuma 5000 CNC." However, after completing the soft limits adjustment, the machine didn't update to correct position. Moving X axis approximately to zero, it showed "X -68.5284."
After re-reading most postings about this in the Forums, I saw several that caught my attention by Okumawiz. There he stated that one could use the PR Zero Offset for the X Axis (my case). One didn't have to change the + and - Stroke End Limits. Based on that, I proceeded to change the limits back to the previous values which are the same values shown in the Data Management Card in the back of the machine. I calculated the differene between my known position and positions displayed on RAPA X and was about 68.6322 which I entered into the PR Zero Offset of X and got the Alarm "Power On Effective Parameter set" just like Okumawiz said would happen. After waiting enough time for the change to get saved, I turned machine off, then back on but Position now was "X -137.1606." I tried a negative value to which I got an Overflow error. I added more and the value became even more negative moving even farther away from 0.
What am I doing wrong? Was the problem caused by the way I replaced the encoder? When I was trying to loosen the center bolt of encoder, motor shaft rotated (just like emxler's replacement years ago). I ended up using a piece of 2 by 4 to block the axis until I could remove the bolt. I replaced the encoder per the instructions in the video mentioned above. When I was trying to obtain the values per the "soft limits" video, I hit the + overtravel limit and couldn't move from there until I manually rotated the axis away by turning the encoder screw. Then, moving the axis slowly with another set of eyes looking I was able to get the new + and - stroke end limit numbers. Emxler mentioned that he had to change the stroke end limits but he "disabled" the overtravel switches to actually go past the hardware limits by 0.2", how do I do that?
If anybody can see what I did wrong and tell me how to undo it and complete the installation, I will really appreciate it.
Thanks in advance.
rlarios
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Re: Okuma LNC8 OSP5020L Replaced X Axis Encoder and cannot adjust Zero Offset
If the overflow occurs, you will need to remove the encoder and "spin" it to a new position if the PR Zero gives you an Overflow. One rev should equal about 1/2" unless there is some additional gearing. It's like an odometer but does have positive and negative limits to its reading range. Once you get it closer to target the PR Zero should be able to get you back to target perfectly without having to change anything else.
Experience is what you get just after you needed it.
Re: Okuma LNC8 OSP5020L Replaced X Axis Encoder and cannot adjust Zero Offset
OkumaWiz, You finally got here. Thank you!Originally Posted by OkumaWiz
I didn't know who to turn to so I asked Copilot and he gave me an answer that didn't work. However, I realized that I had to remove the encoder and spin it a few turns to see whether there would be changes, and there were changes! I ended up spinning the encoder like 152-ish turns, re-installed the encoder and voilá! I got a positive position of X = 3"-ish.
I made sure that +/- stroke end limits were exactly the same as before. The operator helped me to find position zero, I took the value out of RAPA, entered it into PR Zero Offset and, machine was again back in operation.
OkumaWiz, I couldn't have done it without your help based on your earlier postings.
Thank you! Ye da man !
rlarios
Re: Okuma LNC8 OSP5020L Replaced X Axis Encoder and cannot adjust Zero Offset
Glad to hear you got it all worked out!
Best regards,
Experience is what you get just after you needed it.
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