Disappointing second print with UM3E, stringing

[chhu79 0]

After unboxing and setup I tried the first print with a very simple box design and everything looked fantastic. Now I was going for a more challenging print and tried the Earth, with very disappointing results (see picture). Any suggestions what could have gone wrong? The print was done with the spool in the package (350g silver PLA) and default "fine" settings in cura, only adjustment was 5% infill, no support.

 

Thanks,

Chris

[Job_van_gennip 23]

If you print at high overhang angles as you do with this print without using support you will get problems with stringing no matter what you do. You could fight it a little bit by lowering the temperature of you print head a little bit and turning on the retraction. However in prints with this much overhang you will always have this problem a bit. 

 

Kind regards,
Job van Gennip

[SandervG 1,518]

Hi @chhu79, welcome to the Ultimaker community.

 

You have chosen a challenging print for your second 3D print. But the Ultimaker 3 should be able to do it with no problems. 

Unfortunately, even the Ultimaker 3 is subjective to external forces like gravity. This globe has quite a steep overhang, and your print would look much better if you would print it with

a support material like PVA. This would allow the layers at the bottom of the curvature to rest on the support and come out nicer. 

 

Not entirely sure by the look of the photo, but it looks like most strings appear where the land is extruded, with the overhang in mind they were expected to hang there mid-air. 

 

Another thing you can take into account is that the heat of your build plate radiates. Depending on how high you set it, this may keep the bottom layers of your print warm, which makes it even more sensitive to overhangs. 

 

And finally, when you have selected a profile, go to layer view in Cura and see if there are any red or difficult areas. There is also a print simulation in the latest Cura. 

This allows you to catch any errors before you have started your print Good luck! There is a lot of expertise in our community, feel free to make it your own! 

 

[DidierKlein 729]

Indeed, it's not really stringing but more related to the steep overhangs you are printing, this particular print probably won't give perfect results without supports

[chhu79 0]

Hmm, maybe you are right, but I am not entirely convinced that it is an overhang issue. I'll let it print and will post a picture again tomorrow evening. If you are right the upper hemisphere should look fine. The Makerbot Z18 had no (big) problems with the overhang but had of course many other faults... I'll keep you updated!

 

Best,

Chris

 

 

[SandervG 1,518]

The Z18 does not have a heated bed does it? If not, it would have no radiation of the heat and it would be slightly more forgiving towards overhangs. Downside; anything except PLA would be much more cumbersome to print with. You could also try to print such a model without the heat of your heated bed, use an alternative adhesive, and see how that goes. 

[kmanstudios 1,120]

15 minutes ago, chhu79 said:

Hmm, maybe you are right, but I am not entirely convinced that it is an overhang issue. I'll let it print and will post a picture again tomorrow evening. If you are right the upper hemisphere should look fine. The Makerbot Z18 had no (big) problems with the overhang but had of course many other faults... I'll keep you updated!

 

Best,

Chris

 

 

One aspect to keep in mind when comparing things is to not use a false equivalency. In this instance, unless you printed the same model at the same size (Though not the same settings as that would need to vary) you really cannot compare the two machines.

 

But, If you look at your pic, you will see that the strings are the worst at the most parallel part of the model to the build plate and progressively diminish as it becomes more perpendicular to the build plate.

 

Adding to that, the raised geographical areas with teeny weeny lil' points is the point of most contention.

 

I would like to see the final print. Especially at  the top when the inverse issue is at hand: the top parts that become more parallel to the buildplate will want to sink into the surace opposite of wanting to hang from the surface as on bottom.

 

I can generally get a clean 65° underside of an overhang with no issues. Anything more than that and it starts to get messy on bottom. I have gotten a clean top at 85° overhang, but an atrocious underside. I found this by printing overhang tests from around the interwebby.

[neotko 1,417]

Indeed it doesn’t seem an overhang issue indeed. Even less at High very slow default quality. That model doesn’t have that hard overhangs for a um3 fan. I would like to see the gcode. Are you using latest cura version and the machine firmware is up to date?

 

Also and very important maybe is just no correctly calibrated on x/y plane. They do calibrate it before shipping it but maybe it just got decalibrated due traveling. Is a simple process and just will take 20-30minutes

 

Other problem maybe is because you changed the infill. Less infill gives less time to cooldown the printed pla, and with so little infill the perimeters might not have enough ‘grip’ with the inside and allow the overhang area to curve more, and more because the print doesn’t cool good enough layer after layer. 

Edited December 20, 2017 by neotko

[chhu79 0]

Thanks for the suggestions. I took some more pictures, we are half-way there. The globe has a diameter of 16cm. The Z18 has no heated print bed, so it might be the cause, but I see the same features on the infill, together with under-extrusion. As long as it stays in the interior, of course, I don't care too much. But it is worrisome... I also hear clicking noises when the extruder travels over the model, I guess it is hitting those small parts. Oh and firmware and Cura is up-to-date.

 

Best,

Chris

[DidierKlein 729]

Underextrusion in the infill is probably due to high infill speeds, i personnaly always reduce the infill speeds of the default profiles i find them a bit to extreme.

 

How is the outside doing? Still strings?

[gr5 2,026]

I would lower the temp by 10C.  You can do it live from the TUNE menu if you want.

[Labern 774]

Check your travel settings. you may have "avoid printed parts while traveling" turned on. Its set to a quite large distance by default and can increase travel distances dramatically causing a lot more oozing. Turning this off may help. Also turning off z hop. and reducing the temp like others said by about 10deg. You may need to reduce the infill speed a lot if you reduce the temp as it will under-extrude like crazy. 

Was this a dual extrusion print that you are just printing with one extruder? 

Edited December 22, 2017 by Labern

[chhu79 0]

Thanks for the many advices. In the end the middle and upper section looks fantastic, a lot of detail I've not seen before on the Z18 with the same layer height (0.1). The loose strings from the overhang break away nicely, so after a little touch-up its not a big issue anymore. However, I'll keep in mind to build a support structure with a little lower temperature. The print was done with 2 print cores as I could not figure out how to print with one. I even had to load material and each head was calibrating...  I hope the BB did not stay hot. On the negative side was the NFC stuff, extremely annoying with two spools a message popped up saying it could not read the code, after confirm it popped up again. Had to remove the spools and select manual. Where can I disable this feature?

 

Best,

Chris

 

[kmanstudios 1,120]

I am glad to hear the top worked out well.

 

You mentioned that you could not figure how to use just one print core. By default, when you put in a model(s), it will automatically select print core one. you have to tell it to use print core two either for a second AA core (Second color, usually) or the default BB core (PVA only).

 

Did your Cura do otherwise? That is a nice model though

[geert_2 556]

That is a really nice model. Where did you get that?

 

An alternative to printing the globe at once, with supports, might be to split the model along the equator, print both halves separately, and glue them together? But then you will need to post-process the seams. For good stability, I would make the shell thick enough, maybe 1.2mm?

[kmanstudios 1,120]

1 hour ago, geert_2 said:

That is a really nice model. Where did you get that?......

LOL....I had to go a'huntin' fer meself...LOL You do a general search and find a lot of variations at almost all download sites.

[chhu79 0]

Made this model myself from the ETOPO1 dataset. 30 times exaggerated and 1km bump for >0 elevation to make sea level visible. Projected and properly interpolated on divided icosahedron. The models you find online are all crappy with low-res. The one I printed is 1.2GB STL. I have a similar hires Mars that’s next. If I have some time I make them available on my server. Thingiverse limits at 150MB. Next is to modify the script for 2 color

[kmanstudios 1,120]

Would be nice if the ETOPO1 data set was a true height-field map and not a colored map. Or is there something I missed? I looked it up, but may have missed something.

[chhu79 0]

58 minutes ago, kmanstudios said:

Would be nice if the ETOPO1 data set was a true height-field map and not a colored map. Or is there something I missed? I looked it up, but may have missed something.

Look for geotiff. Topography is encoded in 16bit signed integers. Color is just for visualization. There is also a true height map that gives you the offset to a sphere, but forgot what this version of etopo1 was called.

 

ps: my mistake, stl file is 4gb...

[geert_2 556]

I think for 3D-printing it might be possible to reduce file size to a few 100MB, and still have good quality, as very fine details are lost anyway in a 3D-print?