Not a first print problem: Linear Bearing is scoring metal rod  

RE: Not a first print problem: Linear Bearing is scoring metal rod

Did you lubricate the bearings?

Posted by: @rob-w5

I've had my MK2.5s for a long time.  About a year and a half ago the right Y axis (the one closer to the user interface knob) got scored. I replaced the linear bearing with an LMU8 bearing as well as replacing the scored rod.  Well, guess what?  The very same rod is scored again!  Just feeling the score from front to back, it seems uniformly scored.  As in, it seems to be consistently off all the way from back to front.  And all three bearing columns are scoring.
When I run the calibration wizard I get high marks for alignment.  Is there some twist I can give the printer to stop this from happening?  Is this bad luck and I just happen to be putting defective bearings in the exact same place? Remember, the MK2 uses threaded rods instead of the extruded aluminum, so it would be easy to get this out of square.  I'm not sure what I can do to get this to stop happening.  It's not a serious problem, as I only use the MK2 when the MK3 is already busy.
A solution I have considered is to buy the extruded arms for the MK3 and see if I can modify the MK2 using them, getting rid of the threaded rods altogether.

Looking for ideas to try.

RE: Not a first print problem: Linear Bearing is scoring metal rod

Nope.  There are 10 sets of bearings in these printers.  I'm only having problems with the bearings in this one location.  I recall that when I replaced the bearing last time, tiny balls were all over the place.  I'll replace it again and this time will lube them.  May as well lube all 10 bearings.  20 if you count the other printer.

RE: Not a first print problem: Linear Bearing is scoring metal rod

For those of you who have been on pins and needles hoping for an answer to this, I got it solved.
The Inner dimension from Y Axis bar to bar on the front of the printer was 162.76mm, the back was 163.08.  After I scored yet another rod, I took the bed off, let everything relax, and measured the same dimension with the bard just connected to the linear bearings by themselves.  162.00 mm.  After playing around with the threaded rod nuts, I got within .05mm of 162, which I hope is good enough to keep the rods from scoring again.  I'm not sure if I'm amazed that the printer could go nearly a year before a linear bearing gave out from the lateral force, or that such a small distance (~1mm) was able to make tiny ball bearings scratch stainless steel rods.
While I was at it, I put an MK3+ Bearing clip set on the printbed, and caused a problem I'm resolving as I type this.  The Bearing Clip metal is interfering with the Aft Port (for lack of a better location descriptor) right angle bracket, preventing the end stop switch from making contact.  So I'll have to put the old U bolt back on that.  I can leave the Bearing Clip Set on the other two linear bearings.
I hope this works!  And I'm also losing hope that I'll be able to use the spare parts from the MK3S+ ->MK4 upgrade to turn this MK2.5 into a hodgepodge MK3.  It may be that a Bear Upgrade is in this printer's future.