Knocking sound during U3e print, possibly Z stepper motor?

[randyinla 12]

I've only printed a few things since receiving my U3e over the weekend, but I've noticed a distinct knocking sound that happens during printing.  It sounds like something metallic is loose somewhere inside the build area, causing a "tink, tink-tink-tink, tink, tink-tink" pseudo random pattern of tapping/knocking.  After some investigation, I noticed if I gently place a finger on the Z-screw, I can feel the tapping pattern.  The z-screw definitely is not rotating, but could the stepper motor be 'jolted' somehow as the other steppers are moving around?  Like, a surge of power in the current position that doesn't cause it to spin, but enough to cause it to make a noise?  It's really bizarre as I'm not used to this behavior with my U2 I've had for a few years.

I'll try to make an audio recording on my phone when I get home tonight and post it in a follow up comment.

Edited April 26, 2017 by Guest

[fbrc8-erin 220]

It sounds like it's your active leveling, which is a totally normal sound to hear on the UM3E, but definitely a bit unnerving if you're used to printing on a UM2. I keep meaning to make a video of noise for reference and comparison between the two machines.

The active leveling process makes tiny corrections as your printhead moves across the bed, for the first 20mm of printing height. This is caused by the Z-motor making lots of small movements.

[randyinla 12]

I thought active leveling was just the auto-level part it does before a print? So it actually adjusts the build plate height during the print?! Wow! Awesome! Thanks for the clarification.

[fbrc8-erin 220]

Glad I could help. :-)

The active leveling has 2 parts--it does do the leveling at the start of the print, which is useful, particularly if you're swapping between multiple pieces of glass, but it also corrects during the building. The first 10mm are corrections for the leveling/plate, and the second 10mm phase out those corrections so everything is totally level by the time the print is 20mm high.

[Croy9000 1]

I guess thats what this noise is?

[neotko 1,413]

I guess thats what this noise is?

 

Specially at the start of the video the Y angle smooth rod seems to wooble. I would make a closer video to the shaft entrance on the printhead (slowmotion iPhone can show wonders) and if it woobles I would ask to the reseller to fix that.

[Croy9000 1]

I will try to get another video when it gets to the top layer. Its not doing it in the middle section where there is no solid layer.

[kmanstudios 1,048]

Glad I could help. :-)

The active leveling has 2 parts--it does do the leveling at the start of the print, which is useful, particularly if you're swapping between multiple pieces of glass, but it also corrects during the building. The first 10mm are corrections for the leveling/plate, and the second 10mm phase out those corrections so everything is totally level by the time the print is 20mm high.

 

I did not know it operated on the buildplate during the printing process as well. I did adopt the active leveling at the beginning of the print since moving most prints to the Cura Connect. I used to do it manually, but it does make a difference when changing plates.

But, thanks for the additional info.