Top Layers Are Shiny/Underextruding Towards Middle And Matte/Overextruding On Side
 

Top Layers Are Shiny/Underextruding Towards Middle And Matte/Overextruding On Side  

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graham.shotts
(@graham-shotts)
New Member

Hello!

This print came from a MK3S running the most recent firmware with G-Code generated from the most recent Prusaslicer. In the photo below, it looks like the outer edges of the top layer have signs of over extrusion, especially towards the top of the image where the surface is bumpy, while the middle seems to be slightly underextruded. The photo isn't the clearest (sorry!), but it pretty much looks like the lines are squished towards the outside and have more space towards the middle where it appears shiny. Typically this wouldn't be an issue, but this part is for an architectural lighting company, and I want to keep a consistent surface finish on the whole part.

Thanks for the help!

Posted : 06/06/2020 3:28 am
guy.k2
(@guy-k2)
Noble Member

For better top surface consistency, I would increase number of top layers to at least 4 and slow down speed by 25% for top layer.

Posted : 06/06/2020 6:59 am
m00dawg
(@m00dawg)
Eminent Member

I'm having a similar issue with my second MK3s. Same filament, same gcode, but my older printer prints the top layers beautifully without this odd issue. My new one doesn't. Trying to figure out why. Trying  test cube on my new one now at a much hotter temperature to see what that does.

Next thing is to try upgrading my old printer to the latest firmware (which my new printer is running) to see if that's the issue. If so, it makes me think it may be related to linear advance changes, and I might roll back to the firmware used by my old printer.

I make 3D printed negative carriers for darkroom enlargers. The top layer, as a result, is really important, both in looks and function.

Posted : 20/06/2020 12:13 am
m00dawg
(@m00dawg)
Eminent Member

Sorry for the self reply but I just finished a test cube using firmware 3.8.0 on my new printer (same firmware currently on my old one) and the cubes were virtually identical. My top surface finish is flat and shiny (whereas before with the new firmware on the new printer, it was matte and kinda chalky almost). My suspicion is still linear advance. Anyways Graham, you might try rolling your firmware back to 3.8.0 as well just to see what difference it makes (for me I didn't have to re-run calibration or anything like that so it's pretty easy to roll back and forward).

I'm about to start some real prints on both as a comparison beyond a cube so I'll try to share those results here soon.

Posted : 20/06/2020 1:33 am
peter.m26
(@peter-m26)
Honorable Member

Try higher temperature on the extruder.

Posted : 20/06/2020 4:14 pm
m00dawg
(@m00dawg)
Eminent Member
Posted by: @peter-m26

Try higher temperature on the extruder.

With the new firmware, that kinda of worked but the top layers of my test cube were still not nearly as smooth as with the previous 3.8.0 firmware. And I went from 215 to 240. That's a BIG jump. With 3.8.0 both printers produce nearly identical top layers (in both test cubes and real prints) which are shiny and smooth at 215C. Only difference seems to be the firmware. Now I haven't tried the new firmware on my old printer yet to see if it produces poor top layers like my new one did. I'll try to get to that, though trying to do that in between customer prints so hard to make the time for that.

Posted : 21/06/2020 3:40 am
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