1 Topic by Aldo

  • Aldo
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Topic: Layers jittered

Hello fellow Solidoodlers,

This is my problem:
http://i.imgur.com/zLm5OBM.jpg

What could be the problem here? The jittered layers always start at the same height, so I think my buildplatform is loose. I can't find any way to fix this by myself.

So please help?

2 Reply by 2n2r5

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Re: Layers jittered

Look up Z-wobble or banding. It is probably more of an issue with your 5/16 Z axis rod. It may be bent  or drilled off center.

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

2n2r5's Website

3 Reply by Aldo

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Re: Layers jittered

Thanks a lot.

I'm confused how it could happen. It stardet all of a sudden. Are there any screws which could be loose?

I think I will try a new firmware which allows me to calibrate the Z-Axis wobble. This will be some tedious work, I don't have a Z-Axis wobble for the entire rod. As far as I could see it would be good to run the whole measurement process in .1 steps for the entire build space.

Good thing I didn't have any other plans for this weekend.

Thanks again.

4 Reply by 2n2r5 (edited by 2n2r5 2013-10-26 14:41:02)

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Re: Layers jittered

if it happened all of the sudden then you might also want to check your belts. It wouldn't make sense that they only do that one you get to a certain layer.

You should also check your extruder calibrations. Band can come of over extruding but it doesn't usually look like that.

Try running the Z axis up and down its length. See if there is any wobble at the top of the rod and try to note what position the bed is in when it becomes noticeable.

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

2n2r5's Website

5 Reply by ronsii

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Re: Layers jittered

Hi Aldo, what other calibrations have you done? http://wiki.solidoodle.com/solidoodle-1 it is strange that this just started to happen... the bed leveling screws could possibly come loose but that would affect your first layer as well, filament diameter could have changed which would in turn change your extrusion rate and that can make layer banding more noticeable.

6 Reply by Aldo (edited by Aldo 2013-10-26 15:52:59)

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Re: Layers jittered

2n2r5 wrote:

if it happened all of the sudden then you might also want to check your belts. It wouldn't make sense that they only do that one you get to a certain layer.

I checked the belts. They are not damaged and the traction is okay. But the distance when the print is okay changes. The Z Wobble starts at 10 mm for small parts and decreases to 7 mm for bigger parts.

2n2r5 wrote:

You should also check your extruder calibrations. Band can come of over extruding but it doesn't usually look like that.

I tried different filament diameters and measured the filament. No change in diameter here. The extruder works great.

2n2r5 wrote:

Try running the Z axis up and down its length. See if there is any wobble at the top of the rod and try to note what position the bed is in when it becomes noticeable.

The wobble on top isn't really noticeable, but in the middle it definetly has a wobble. The top turns really nice. I has the shape of a bracket: (
Maybe I should replace the rod? I still can't think about any situation I could have damaged/bent the rod.. it seems to be the toughest part on the entire printer!

ronsii wrote:

Hi Aldo, what other calibrations have you done? http://wiki.solidoodle.com/solidoodle-1 it is strange that this just started to happen...

  Z Axis / Bed leveling / Extruder (filament) calibration. The dimension accuracy is higher than 90% so I'm pretty glad with that.

ronsii wrote:

the bed leveling screws could possibly come loose but that would affect your first layer as well, filament diameter could have changed which would in turn change your extrusion rate and that can make layer banding more noticeable.

The bed screws are tight and the bed is planar.


Edit: http://i.imgur.com/i0wqbnm.jpg

I compared the prints, the pattern has the same amplitude and frequency, I still don't think it's sine, but maybe with some fantasy it could be one. So it is predictable (yeah!). But,... how to calculate it out? It doesn't start at the same height! The size of the object matters!

7 Reply by Hazer

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Re: Layers jittered

Grease your Z rod.

Let me know.

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8 Reply by Aldo

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Re: Layers jittered

Hazer wrote:

Grease your Z rod.

Let me know.


I have greased my rod (badum tss), but the wobble still remains.

http://i.imgur.com/5iopzDx.jpg

The printing quality is in fact a little better than before, but I also tried the Z-Axis wobble M 97 G-Code. The result is a tiny wobble in the first 10 mm and a less visible wobble in the rest of the print. So it is still there, it is just "averaged" over the entire build height and hence, less noticeable.