Printing a building plan 3D model made for VR

[JojoL 2]

Hi everyone.

I´m having some issues with a print that I´m supposed to do. It´s part of a model of a building (that´s actually being built right now) that was originally made for "walking" through the building in VR (so it´s a highly realistic model).

It all comes down to stubborn stringing issues I guess, but I wanted to get some second opinions.

Here´s a picture of the model, so you get an idea:

And here´s how the print turned out most of the time:

(sorry if this is not the best picture)

Alright, so I gave this several shots, these are the settings I used:

printer: Ultimaker 2+ (Ultimaker 2 with extrusion upgrade)

Nozzle: 0.25mm (!)

Layer height: 0.06mm

Print speed: 30mm/s

Travel speed: 120mm/s

Retraction: yes (standard settings at first, then up to 40 or 45mm/s IIRC, not sure about the distance anymore, but turned it up as well.)

Material: white PLA (material4print)

Temperature: 195°C (also tried 200°C at one point, was too much I think)

So a big problem that we´re facing is that some structures of the model (especially some wall parts) are too delicate to be printed correctly (or at all) resulting in a fairly crappy print. "Replacing" these missing structures with support structures only made the stringing worse.

These would be my next steps / ideas:

 

• reducing the temperature further, maybe also reducing printing speed
  
• increasing travel speed
  
• other filament color (as I have read that white PLA is the worst when it comes to stringing?)
  

 

Most importantly I guess we will try tweaking the model (increasing all the thin/small structures).

Am I going in the right direction here? Do you have any more / better ideas? Is the "small" 0.25mm-nozzle of the UM2+ especially prone to have these issues?

Thanks in advance!

[gr5 2,067]

I have no idea if .25mm nozzle strings more. White filament definitely strings more. I would do a few things.

UM2 can travel up to 300mm/sec. Try at least 200mm/sec. This helps to break the strings.

I'm pretty sure .06mm is worse for stringing. Try .15mm for .25mm nozzle or .2mm layers for .4mm nozzle.

There is a setting in cura - horizontal expansion? Something like that. It can compensate for all wall thicknesses without you having to modify your STL. It can make all walls thicker. You might have to enter a negative number. I forget what it's called but it's a fun parameter to play with.

Do not use any support.

Make sure fan is at 100%.

Cooler is better. 195C was smart. 180C smarter. But that might underextrude. You can play with temperature a bit.

Make sure retractions are at max - there is something like "minimum gap for retraction". Set that to 1mm - if the gap to traverse is less than this it won't retract. Also there is something like "minimum extrusion between retractions". If this is too low you can grind the filament but you should be okay. The default retraction is 4.5mm and if you set this to .45mm you will get no more than 10 retractions for every spot of filament. Maybe set this to .1mm so there are more retractions on your model.

Turn off infill. You don't need it and it just makes for more retractions.

[JojoL 2]

There is a setting in cura - horizontal expansion?  Something like that.  It can compensate for all wall thicknesses without you having to modify your STL.  It can make all walls thicker.  You might have to enter a negative number.  I forget what it's called but it's a fun parameter to play with.

 

Thanks a lot man, horizontal expansion was a game changer. Didn't know about this.

This is what it looks like now: