Ultimaker 2/cura - ugliness on right-front side of print

[andete 0]

Hey,

I'm trying to tune my still quite new Ultimaker 2 and am using this quite tricky item for it: https://www.thingiverse.com/make:61855 .

So far I've tried lowering speed, playing with different layer heights, slightly lowering the temperature, using support, and disabling "Combine Everything Type-A".

Plastic: Faberdashery black PLA. Printing at 210. 50mm/sec.

What I am seeing at all settings is ugliness on the front right sight of the print. I'm not sure whether this is a printer issue or a cura/slicing issue.

Picture of left side: http://damad.be/joost/attic/priv/um2_c_left.jpg

Picture of right side: http://damad.be/joost/attic/priv/um2_c_right.jpg

Do you have an idea what might be going wrong here? The left side clearly shows that the UM2 can print this properly without support, the right side on the other hand looks really ugly.

Thanks, Joost

 

[takei-naodar 0]

The Problem is the right side gets not cooled fast enough.

 

[andete 0]

Why is that the problem? Why is the left side cooling fast enough while the right side isn't?

 

[IRobertI 521]

Because of how the fans are arranged. If you look you'll notice that the right fan is further away from the nozzle. There's also a bit of metal in-between that can block air flow on small parts. On slightly larger parts this isn't a problem as the nozzle will move longer distances and allow both fans to hit the print (and it'll also take longer to print each layer so that it has more time to cool down). On small parts the head barely moves, so the right fan has a hard time getting in there to cool things off.

What you can do to help with this is to print more than one object at the same time, that way the head will jump between the two and each layer will get a chance to cool off a bit more.

Increasing the minimum layer time (within reason, too long and the nozzle will barely move thus dumping lots of heat into the print), printing colder, reducing bed temperature are other things that may improve the result.

 

[andete 0]

Thanks |Robert| :cool: That explanation makes a lot of sense. I'll try some of your suggested approaches, and be sure to report back!

 

[andete 0]

Ok, changing cool to 10 and setting the print temperature made a difference, but actually the real trick was just to turn the model 90 degrees. By moving the complexities to the front and back of the print it almost entirely removes the issue!

You can see some pictures of the final result printed at 0.08 at: my G+:

 

[gr5 2,265]

If you just print at 30mm/sec instead of 50mm/sec it will have much more time to cool between layers and it should help quite a bit. Also the pressures in the nozzle will be lower so it won't over/underextrude every time it speeds up and slows down.

Printing slower always improves quality. I usually prefer to print fast.

 

[andete 0]

Thanks gr5. What I mostly took away from this is that when printing smaller, print slower. Indeed on larger prints I'm not seeing the issues. I haven't tried printing faster then the defaults. Looking in the settings it should be possible to print quite a bit faster. Lots of cool things to try!