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Nicolinux

Smooth walls

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So I have a thing with very faint issues - sorry for that :)

Many months ago I printed lots and lots of stretchy bracelets. I gifted most of them and wanted to print a few. Now I am unable to achieve the same print quality like before. The vertical walls are not smooth any more (I think this is related to this post):

Now

actual_1.thumb.jpg.4b2ad26cf8c34e88f61b35bc93b6e042.jpg

actual_2.thumb.jpg.1fa97be2a153f0391317db71e9c61144.jpg

Then

smooth_1.thumb.jpg.7ab8c3e0f6e6ab932a1b042fb67e2f2d.jpg

smooth_2.thumb.jpg.32466fa24e63677ee57026ce0170bb60.jpg

I am not only concerned with the inner walls. On the older bracelets the outer wall is completely smooth too (you only see some dents because the model was low poly):

smooth_3.thumb.jpg.50cddecdd0d597702b074d6cb1e94d7e.jpg

However, at first I thought the long belts were a bit too loose. I added this belt tensioner on all four of them but it does not make a difference.

um2_belt_tensioner.thumb.jpg.ac9eaf25e9418220d62ff6f7e6fe7cb3.jpg

I have also tightened all other pulleys a lot but still o difference. Z-screw is greased, heated bed does not wiggle. Pulleys do wobble but they always did... What could this be? Hardware issue? Filament?

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Did you completely wipe clean the z screw before regreasing, as tiny plastic dust tends to settle there, making sure the thread is clear? its the only thing i can think of, as just adding grease wont help as much, if bits are still in there.

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Alright checked everything you two mentioned. There is no play in the x/y gantry. The feeder motor is new (part of the Extrusion Upgrade Kit).

I have disassembled the z-nut/stage and completely cleaned the threaded rod. I noticed though that the z-nut has quite some play. Is this "normal"?

 

The z-stage without the rod moves fine and without resistance. The bearings are a bit loud but I guess that's fine.

 

After assembling everything again, I remembered this sound. Check out the video and turn the volume up. In the first few seconds when the z-stages moves there is some kind of crackling sound - like there is plastic foil trapped between the threads (which isn't the case...). It was always like this - since I've got the printer.

 

I am printing two test objects to see if something changed after cleaning the threaded rod.

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@nicolinux remember what I told you about the z layers on the octopus shoots you made?

Edit: https://ultimaker.com/en/community/11123-z-axis-layer-error?page=last#reply-130203

That z wooble and worse I found on one of my umo+ kit. I bough a 6€ nut from pololu and the difference it's quite amazing. If you want you could renew the linear bearings also for 6€ each from misumi (the cost effective range). It's quite smoooth the change. But the main part it's the nut.

Edited by Guest
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I also have a weird crackling sound like a packet of crisps mainly during retractions and the last move of he buildplate when its finished, but its intermitten and also much lighter sounding than yours, but time will tell i guess.

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Ok, I have assembled everything and printed a bracelet and an octopus. The bracelet doesn't look better, the octopus only slightly. The z-stage sounds weird now. Maybe I need even more grease...

not_smooth.thumb.jpg.074f2144190aaed6439c65d6f5a3baec.jpg

octo.thumb.jpg.2a7c99b1bd1b049e366bec6f43afebd1.jpg

I think I'll replace the bearings and the nut. The question is - where to get them? The bearings are here (although @neotko praised the Mitsumi thingies):

https://shop.stoutwind.de/Linearkugellager-mit-Flansch-LMK12LUU

not_smooth.thumb.jpg.074f2144190aaed6439c65d6f5a3baec.jpg

octo.thumb.jpg.2a7c99b1bd1b049e366bec6f43afebd1.jpg

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Misumi deliver quality at a price. All my umo+ has misumi shafts and they work work work :D The bearings are less problematic if the nut it's perfect. But if the nut has wooble the bearings can make that the bed stucks a bit on each z move.

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Alright, ordered the z-nut here. I installed it but sadly it has some play too :(

 

Round objects (the cute octopi for example) is a little better but straight walls like these on the stretchy bracelet are still bad :/

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I tested the old and the new one at different heights on the z-screw and there is play everywhere. So I guess not. The question is - is my z-screw thinner than the norm or are all z-nuts that I tried too big?

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I just solved some z ridging by printing hotter, I went up 10C.  It's an easy test to see if that helps you. it did for me (although I'm still trying to find a real fix for my issue, since printing hotter is a band aid not a fix)

here's the same print just changing the temp by 10C

5a331a472b094_zwaveTEMP-words.thumb.jpg.a3b6185a041265b3ef7e2b5d80003098.jpg

here's the on going testing.

5a331a472b094_zwaveTEMP-words.thumb.jpg.a3b6185a041265b3ef7e2b5d80003098.jpg

Edited by Guest

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Bad news everybody. I've swapped the linear bearings and smooth shafts with expensive ones from Misumi. I have also replaced the brass z-nut. The print quality didn't change at all :( :(

So it must be something else. D A M N!

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I recently also had a strong irregular banding. I ended up changing the glass filled teflon from Ultimaker to a TFT coupler from 3dSolex (both with an I2K disc), cleaning the whole hotend as I had some leaking before.

As I had to disassemble anyway the whole print head, I also exchanged the original 25W heater with a 35W heater. There I found that the copper grease I have used was completely dried up; it seems any contact fluid has to be renewed every few hundred printing hours. Maybe some of those things also help you...?

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Bad news everybody. I've swapped the linear bearings and smooth shafts with expensive ones from Misumi. I have also replaced the brass z-nut. The print quality didn't change at all :(:(

So it must be something else. D A M N!

So... You have changed in 6months:

- board

- um2+ kit

- x/y x4 shafts

- z nut

- reassembled almost all

Check the hotend assembly like foehnsturm says here https://ultimaker.com/en/community/20709-again-wallslayers-not-touching-advanced-question?page=last#reply-145078

Maybe it's just too much preassure on the hotend. Also check the copper grease like dim3nsioneer says.

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