Smooth walls

[Nicolinux 288]

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

Then

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):

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.

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?

[cloakfiend 995]

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.

[mastory 44]

Is there any play in the nozzle mounting to the XY gantry?

[cloakfiend 995]

Have you tried printing off the roll? maybe your feeder motor is getting tired? Worth a shot.

[Nicolinux 288]

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.

[neotko 1,417]

@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 March 22, 2016 by Guest

[neotko 1,417]

C-LHFSW12

https://ultimaker.com/en/community/18394-sounds-like-theres-sand-on-the-z-screw#reply-135067

Frb8 did send a misumi bed bearings to a customer. I bough x4 of the cost effect Ve range and not only they fit, they moove sooo smoothly (bed falls down by itself everytime).

[neotko 1,417]

@veedee made a printable nut and seems it works too

https://ultimaker.com/en/community/19321-random-z-layer-underextrusion-umo-with-hb-upgrade#reply-133434

Edited March 22, 2016 by Guest

[cloakfiend 995]

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.

[neotko 1,417]

Sound from bearings (like sand) it's perfectly normal. You are fine unless you have a woobly nut or bearings that get stuck (hard) on some points.

[Nicolinux 288]

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...

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

[neotko 1,417]

Misumi deliver quality at a price. All my umo+ has misumi shafts and they work work work 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.

[neotko 1,417]

The nut you can google the part number of the photo. I got them from a pololu reseller in uk

[Nicolinux 288]

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 :/

[neotko 1,417]

:S!

[Nicolinux 288]

I noticed they sell the entire stepper+z-screw+z-nut too:

https://www.pololu.com/product/2268

But I don't know if I want to shell out ~55€ for another test. I might be that the nut has some play there too.

Apparently @neotko got really lucky with his z-nut:

 

[neotko 1,417]

You could try, using a high preassure spring, and thenold nut, to make a antibacklast nut.

[neotko 1,417]

It's there any chance that tour z screw got damaged overtime? Does the nut has the same play along all the z screw?

[Nicolinux 288]

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?

[peggyb 171]

I bought 3 of them (for 2 printers) to have a spare one if tolerances where out of spec., but they were all great. Delivery costs are ok because you can ask for an untracked envelope.

http://www.technobotsonline.com/tr8x2-travelling-nut-for-threaded-rods.html

[Nicolinux 288]

Thanks Peggy. So I've either hit a bad batch or my z-screw is screw... bad. I wrote the exp-tech folks where I ordered my z-nuts and we'll see what they say.

[peetersm 124]

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

here's the on going testing.

Edited March 29, 2016 by Guest

[Nicolinux 288]

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!

[Dim3nsioneer 557]

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...?

[neotko 1,417]

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.