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Large thin-walled print becomes badly warped, possible fixes?

Posted by HugoW 
Large thin-walled print becomes badly warped, possible fixes?
January 02, 2018 06:27AM
Hi,

I am working on an RC truck project and yesterday I printed the hood of the truck. Or I tried. The part is 270 mm wide (y direction on the bed) about 140 mm high (x direction on the bed) and 150 mm long (z direction on the bed). The walls are 1mm thick. When it prints, it only prints two 0.4 mm wide walls parallel, no infill. The result is ugly. Print pics:















And the print was not finished. It flexed too much and couldn’t print nicely anymore about 125 mm into the print (z direction). I have printed 2 mm walls successfully, it then prints 2 layers width outer walls and inner walls, so together 1.6 mm wide, and hardly any infill in the 0.4 mm gap. But those surfaces were not so large, only 200 (x or y) x 50 (z) mm or so. The easiest fix would be thicker walls, I know. But is there a way to make this work with other settings? I am considering to try 1.2 mm thick walls and 100% infill, effectively printing three layers wide. Or 0.8 mm wide, with the two walls touching so it is more strong / stable. Or is the temperature or speed at fault, I am printing this in PLA at 200° C at 50 mm/s.

Any advice is welcome,
Cheers,

Hugo
Re: Large thin-walled print becomes badly warped, possible fixes?
January 02, 2018 06:33AM
No clue why the pics don't load, if I click on the link it does show. Does it show for you?
Re: Large thin-walled print becomes badly warped, possible fixes?
January 02, 2018 06:36AM
It says Permission Denied. Did you put the pics in your private folder?



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Large thin-walled print becomes badly warped, possible fixes?
January 02, 2018 06:44AM
Fixed it, sorry, my bad... Pics should be visible now. If you tried before just refresh (F5) to load the pics.

Hugo
Re: Large thin-walled print becomes badly warped, possible fixes?
January 02, 2018 07:14AM
Do you have a print cooling fan on the hot end? If so, how effective is it, and which way does it face?



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Large thin-walled print becomes badly warped, possible fixes?
January 02, 2018 07:29AM
2 things:
- smaller nozzle (0.3mm) and 0.33mm extrusion width (which will give you 3 lines for a 1mm wall)
- use a part cooling fan
Re: Large thin-walled print becomes badly warped, possible fixes?
January 02, 2018 02:17PM
If you've got 1mm walls printed as two unconnected 0.4mm perimeter lines, something this size is going to be hopelessly floppy. Firstly, you need to fix your slicer settings - either specify a 0.5mm line width so that the two perimeters merge into a solid thin wall, reduce the minimum infill parameters so you is tries to infill the small gap, or use a slicer like Simplify3D that can produce variable line widths to make sure thin walls like this are completely filled.

Even with solid walls, 1mm thick sections on something as large as this are going to move around some as you print and give you a rippled surface finish. It'd be best if you could design in some break-away ribs on the inside to stabilize the walls as it prints.
Re: Large thin-walled print becomes badly warped, possible fixes?
January 02, 2018 02:18PM
I don't have a part cooling fan, yet, but I guess that is required now. I might go for 1.2 mm walls, keep the 0.4 mm nozzle on. How do you set extrusion width? Is this something I should measure and teach Cura, or do you set it in Cura?

Cheers,

Hugo
Re: Large thin-walled print becomes badly warped, possible fixes?
January 02, 2018 02:34PM
Quote
HugoW
How do you set extrusion width? Is this something I should measure and teach Cura, or do you set it in Cura?

I don't use Cura, but I believe it simply selects a line width equal to the nozzle diameter, so you could just set the nozzle diameter to 0.5mm. (Note that the nozzle diameter is not used in calculating how much material is extruded - it is really only used for establishing minimum and maximum allowable line widths.) In general, I'd suggest using a slicer like Slic3r or Simplify3D that gives you much more control over thin wall print settings.
Re: Large thin-walled print becomes badly warped, possible fixes?
January 02, 2018 03:03PM
if using cura, change shell thickness to be thicker. this will make the walls thick enough to touch each other. you want them to bond to each other, if too thick cura won't lay down inner shell. adjust thickness, and watch preview of part. (view mode:layers)
Re: Large thin-walled print becomes badly warped, possible fixes?
January 03, 2018 03:43PM
Thanks. Zooming in on the layers view in Cura (I just figured out I could zoom in), I can actually see it prints two walls that don't touch. And that is indeed what it does, not only in the simulation:



So I need to make the drawing such that the walls are 1.2 or 1.6 width. I can do that. Maybe even overextrude a little bit to make the walls glue together better. And I made a make-shift product cooler tonight:



It seems a bit weird to cool the hotend this way, too, a bit, but it is a constant cooling so the hot-end should cope. Although I am looking into some form of insulation, cann't be bad to shield the hotend from external influences. By the way, the nose of the cooler is 0.8 mm wide wall, it indeed prints two layers that touch. They cohere nicely and the part seems quite strong.

Cheers,

Hugo
Re: Large thin-walled print becomes badly warped, possible fixes?
April 20, 2018 05:12PM
Hey Hugo out of curiosity where did you get throes stl files from to me it looks like a rc semi I would really like to build one myself what's the chances off getting them from you thank you
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