Uneven layers? Although I print at .1 mm I am still able to see every layer...help please

[Kwallnation 1]

This is most likely your Z stage.  It could be that your nozzle is varying by more than 10C in temperature slowly - so check that first as that's easy to test while printing.  and it could be filament that varies wildly in thickness.  But most likely it is the Z stage.  Probably the linear bearings and not the Z screw.  You want to keep those vertical rods very clean and no oil is needed - in fact it's better if there is some friction as the ball bearings like to roll and if they don't roll or get clogged with oil it can be a problem.

I recommend taking it apart and removing the 2 vertical bearings and cleaning it out very well with WD40 and drying it completely with rag or something similar and making sure they slide nicely and putting it back together.  Other people have had similar problems and fixed it by cleaning the 2 bearings.

 

I changed around the filament and it appears that the filament was defective because with a different spool it prints just fine. I will take a look at your solution though. Also, this is the second time that my Ultimaker filament has come defective, is there another brand that would work just as well? Preferably in the US?

[gr5 2,167]

In USA I recommend colorfabb from printedSolid.com.

[Kwallnation 1]

Thank you very much for your help. I will try it out.

[Kwallnation 1]

In USA I recommend colorfabb from printedSolid.com.

 

After using Colorfabb filament, print quality has improved but the problem is still there. We have just tried cleaning off the Z-screw as well as removing and trying to clean the bearings; however there is still some sticking as I move the build plate up and down. Any advice to fix?

[Labern 774]

When you had removed the bearings did you slide them up and down the shaft on their own to see if they stick? You cant really clean bearings. If there is a damaged ball or race then you need to replace it.

[Kwallnation 1]

Yes, I moved them up and down but if I raised the bearing to the top of the Z-guide rail and released it, it would tend to stick in some places and would not independently slide to the bottom of the shaft. Could this be a problem with the guide rods instead of with the bearings? If not, any ideas??

[Labern 774]

I would think its the bearing more them the rod. Can you see any wear marks on the rod? or you can measure it where its sticking.

[gr5 2,167]

If it's the rod it will stick in the same place and both bearings will stick in the same place on the same rod.

[Kwallnation 1]

Alright, thank you. I also just disassembled and cleaned out both the Bowden tube and the feeder. I am waiting on a test print to see how these changes affect the quality.

[gr5 2,167]

it would tend to stick in some places and would not independently slide to the bottom of the shaft.

 

It should be amazingly smooth. I don't see how cleaning bowden or feeder will help the Z bearings.

[gr5 2,167]

I have a question for you. I have a new theory that explains some things. I noticed it seems like lots of people have banding due to Z issues in the last few months. Also one guy with 3 UMO+ has the same problem on only one of his machines. He noticed that the machine that is different has a lot of play: when he lifts the bed it moves up and down about 1mm without the shaft having to rotate. This is not true of his other 2 machines. The UMO+ has similar and maybe identical Z nut as the UM2 printers.

I'm wondering if there is a new batch of Z nuts (or Z screws) that have more play than the older versions of the hardware. And this is creating Z banding for a number of people (say maybe 2%? Which is a lot when you are as big as Ultimaker).

@kwallnation - could you test this? lift the bed and release several times to see if it moves at all. Mine will not move even .01mm without the shaft turning.

[JohnFox 25]

Run your fingers over the rods and see if you can feel anything at all, they should be perfectly smooth. However, I strongly suspect the bearings, not the rods.

The bearings should slide up and down the rods without any hold up at all. Maybe the balls have got out of alignment, moving up and down with a bit of a twist should set them OK again.

Are the rods completely free of oil? I think this is quite important, I had a similar problem and it was caused by oil on the rods. Wipe the rods with some Kleenex and run the bearings up and down until they are free.

 

Yes, I moved them up and down but if I raised the bearing to the top of the Z-guide rail and released it, it would tend to stick in some places and would not independently slide to the bottom of the shaft. Could this be a problem with the guide rods instead of with the bearings? If not, any ideas??

 

[Kwallnation 1]

I have a question for you.  I have a new theory that explains some things.  I noticed it seems like lots of people have banding due to Z issues in the last few months.  Also one guy with 3 UMO+ has the same problem on only one of his machines.  He noticed that the machine that is different has a lot of play: when he lifts the bed it moves up and down about 1mm without the shaft having to rotate.  This is not true of his other 2 machines.  The UMO+ has similar and maybe identical Z nut as the UM2 printers.

I'm wondering if there is a new batch of Z nuts (or Z screws) that have more play than the older versions of the hardware.  And this is creating Z banding for a number of people (say maybe 2%?  Which is a lot when you are as big as Ultimaker).

@kwallnation - could you test this?  lift the bed and release several times to see if it moves at all.  Mine will not move even .01mm without the shaft turning.

 

Thats a very interesting theory! I will for sure try it and get back to you with the results. Thank you.

[Kwallnation 1]

I have a question for you.  I have a new theory that explains some things.  I noticed it seems like lots of people have banding due to Z issues in the last few months.  Also one guy with 3 UMO+ has the same problem on only one of his machines.  He noticed that the machine that is different has a lot of play: when he lifts the bed it moves up and down about 1mm without the shaft having to rotate.  This is not true of his other 2 machines.  The UMO+ has similar and maybe identical Z nut as the UM2 printers.

I'm wondering if there is a new batch of Z nuts (or Z screws) that have more play than the older versions of the hardware.  And this is creating Z banding for a number of people (say maybe 2%?  Which is a lot when you are as big as Ultimaker).

@kwallnation - could you test this?  lift the bed and release several times to see if it moves at all.  Mine will not move even .01mm without the shaft turning.

 

@gr5: I moved the build plate up and down and there was no play in the Z-screw. I couldn't move it at all without the shaft turning. It appears that this is not the problem that is causing the Z-banding in my case.

[peggyb 169]

gr5: do you mean this? on my new UM2Go, I had banding from the start, after cleaning the rods it got a little better but there is still something at the same spot.

 

after cleaning the rods:

before cleaning the rods:

[JohnFox 25]

That looks like a lot of play on the print bed.

Can you raise the print bed and check the 4 bolts holding the Z nut. Wonder if they are slack.

 

gr5: do you mean this? on my new UM2Go, I had banding from the start, after cleaning the rods it got a little better but there is still something at the same spot.

 

after cleaning the rods:

before cleaning the rods:

 

[peggyb 169]

the play is in the z-nut on the bed. Did also try the advice on this page: https://ultimaker.com/en/community/11123-z-axis-layer-error?page=last#lastreply

to loosen the screws on the bottom, but that didn't do anything.

This is a combination of the play in the z-nut and some friction in the bearings. When the bed comes to a spot with friction it lifts the bed up until the play of the z-nut drops it again.

To proof this I put a weight of about 500 grams on the bed and printed the same file again.

right: without weight, left: with extra weight.

[JohnFox 25]

That all makes sense, those *&%@$£! Z bearings are causing a lot of problems recently. I suspect that their tolerances aren't compatible with the pillars.

 

the play is in the z-nut on the bed. Did also try the advice on this page: https://ultimaker.com/en/community/11123-z-axis-layer-error?page=last#lastreply

to loosen the screws on the bottom, but that didn't do anything.

This is a combination of the play in the z-nut and some friction in the bearings. When the bed comes to a spot with friction it lifts the bed up until the play of the z-nut drops it again.

To proof this I put a weight of about 500 grams on the bed and printed the same file again.

right: without weight, left: with extra weight.

 

[peggyb 169]

when I lift the bed up by hand you can hear a crunchy sound at a few places, like there is sand in between and harde to push...

I was looking to get them out, but that means getting the bed out.... and that means taking the whole thing apart?? Do the rods go out from underneath? Everything is soo tiny and close together on the UM2Go...

[Kwallnation 1]

when I lift the bed up by hand you can hear a crunchy sound at a few places, like there is sand in between and harde to push...

I was looking to get them out, but that means getting the bed out.... and that means taking the whole thing apart?? Do the rods go out from underneath? Everything is soo tiny and close together on the UM2Go...

 

peggyb: That is my problem too! When I lift my UM2 bed up by had I hear crunching noises in certain spots! I don't know how to solve this!

[peggyb 169]

I hope that replacing the bearings will solve this, because even with the weight on I can see a faint line at the same spot on all prints. And I don't want to carry that extra weight on a portable printer....

[neotko 1,417]

I tried:

- Taking out the shafts and inverting them. Didn't work.

- Chemical cleaning the linear bearings as I readed on a cnc forum. It didn't help.

- Did some measures on the z rod as instructed by the shop where I bought it and on the areas that it stuck there was a very 0.01-0.03 size difference. But I don't trust much this.

So to be sure Trideus it's sending me a complete z and bearings to change.

I had some free trade time yesterday and took out the nut of one of the working umo+ and the nut did wooble the same on the problematic umo+. So it might be a mix of stuff failing.

Could you check the z screw with a caliper gauge on the areas it jumps?

[peggyb 169]

in my case it is the bearings (I am sure). At certain spots they don't slide down by themselves, and because of the play in the z-nut, a few lines are printed on the same height, until the z-nut picks the bed up again. This results in a thicker rigs in the print followed by a thin sparse layer.

I could simulate this by pressing by hand under the bed during a print, simulating the obstruction of the bearing, the same ridge on the print appeared.

If your bearings are fine, the bed just slides normally down. On my 2 UMO's with heated bed there is also a little play in the z-nut, but the bearings are fine. On one UMO the bed slides down by it self, but the bed of an UMO2Go is much smaller and does not have the weight to slide down. I have to put a lot of force (close to the end of the bed) to get it up and down.

[neotko 1,417]

Yes I have the same exact issue. The bed moving by hand can't pass the problematic points without force and my nut has a good mm of play. I linked to trideus this and other posts and they insist on trying to change the z screw & nut and bearings to completely remove the problem.

I bough also an extra nut from pololu uk dealer but hasn't arrive yet. I plan to use the extra one to make a z nut dampener with some good springs from other proyect.

[peggyb 169]

hope this helps!