Loud squeak when lowering build plate

[LloydXmas 0]

When I lower the build plate on my UM2+ after a print is done, there a semi-loud high pitched squeak as the plate starts to descend. I've used Magnalube on the lead screw and added a couple drops of sewing oil to the rods on either side of the lead screw, but the squeak persists. Does anyone have ideas of what may be causing this or what I could try doing to fix it? Thanks  

 

[gr5 1,436]

No ideas.

 

[ahoeben 1,008]

How loud is it? Do you hear the pitch of the squeek change at the start and end of the movement, as if it is accelerating and decelerating? Isn't it just the sound a stepper motor makes?

[fbrc8-erin 220]

Are you using the standard spool holder or a different one? I've seen a couple cases where third part spool holders were a little large on the interior of the printer and got caught when the bed was going down.

 

[LloydXmas 0]

Thanks for the help. The squeak isn't deafening, but it is loud and sharp enough to notice in another room. I am using the original spool holder. I've had the unit for a year and it started doing this about a month (or so) ago.  It only happens when the build plate is up (e.g. after a print is done) and I lower it. The sounds only seems to occur during the initial part of the descent. Here is clip I took with my mobile; the video doesn't really capture the loudness all that well.

 

 

[geert_2 427]

Sounds like it scrapes something somewhere? If you would have a small mirror, such as a dental mirror or hobby mirror, maybe you could look behind it when moving the plate up and down? Or if you move it up and down manually with power off, do you feel anything?

 

[fbrc8-erin 220]

When you lubricated the Z-screw, did you clean it first? I'm starting to wonder if maybe there's some debris in the threading.