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Support Settings for ABS cup with overhangs


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Posted · Support Settings for ABS cup with overhangs

Hi Everyone,

 

I've been trying to print this portafilter dosing cup model (for an espresso machine)

 

https://www.thingiverse.com/thing:4648455

 

And for the life of me, I've been having problems trying to support the small lip sticking out around the edges without causing issues with the surface quality on the outside of the cup.

I'm using Cura 4.6 and currently setup simple supports using the Cross type with walls to keep them from collapsing. The cross type creates four gaps in the support material to allow airflow between the outside walls and support walls. But when the part prints (I'm using ABS), the outside walls shielded by the support material look discolored and have some layer separation in spots (see pictures below).

 

139437114_740856326811383_27848270653030

 

139797737_740860803477602_10918732556535

 

139603379_740860823477600_64128102158301

 

I suspect that it is not being evenly heated because of the supports and am trying to find a simple way to redo the supports so they are not completely shielding the sides. Doe anyone have any ideas of how to best make supports for the lip around the outside of the cup? Ideally, I want to make them open so air can get to the sides.

 

This model was printed on an Airwolf3D AXIOM Dual Direct Drive Printer.

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    Posted · Support Settings for ABS cup with overhangs

    If you could redesign the overhanging rings to be at 45° or 60°, instead of 0° (where 0° is horizontal and 90° is vertical), they could print without supports. I don't know that machine, so I don't know if these rings are functionally required or not? Or if they could do with a shallower angle? That would seem the best option, if functionally possible, since you don't need supports then.

     

    If you do need the rings at 0°, and thus do want supports, but you don't want them to go all the way down, you could also design custom free hanging supports, like I did in these models. But test that on a small model first, because it will require some fine-tuning. They can easily be cut-off without doing much damage to the model, due to their tiny connection strands. Usually I make the connection strands ca. 0.5mm wide, 1mm long, and 0.2mm high (=2 layers of 0.1mm). In the bridge below they do touch the bridge's side panels. But in the slider-housing they are totally free-hanging, and are kept in place by the stringing of the filament, which makes them really easy to remove. But as said: test this on small models; it may require fine-tuning.

     

    overhangtest11c2.thumb.jpg.a46d23123127b77f81082a2efa4daa80.jpg

     

    overhangtest11e.thumb.jpg.1f92bf0e3eb064e1d9edbdf9edd16b3c.jpg

     

    DSCN5727b.jpg.8aeeef6796d24bf7adbbdaa5eb24f52a.jpg

     

    DSCN5751b.jpg.6fe2a62d2f784ac49dee578aca5c2479.jpg

     

    supporttest12b.thumb.png.504e11c4d360abd18960d889c271f2a4.png

     

    supporttest12c.thumb.png.a4bbb089d43486b97df974e68e645196.png

     

    supporttest12d.thumb.png.928a8b2050f412c67de15eea58791d75.png

     

     

    Further, acetone-smoothing the model might also be an option, after sanding to remove the biggest defects: that should fill the gaps and create a nice gloss.

     

    Apart from that, ABS is known to cause underextrusion problems, because its extrusion temp is very close to its decomposition temp, causing it to degrade in the nozzle and partially clog it, if I understood that well. That could also be a reason for temporary gaps in the side.

     

    I am not familiar with high-temp polyesters, so I can't give much recommendations about using them as alternative materials. Maybe other people here can? Standard PET probably won't go high enough, I think ca. 80°C?

     

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    Posted · Support Settings for ABS cup with overhangs

    Hi,

    the suggestions of @geert_2 are very sophisticated and always worth to be thought of.

    But you could just use "make overhang printable" in the "experimental" section in Cura. This will lead to a 45° "ramp" at the underside of the overhanging ring and making support obsolete. Just try and refer to preview.

    Regards

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    • 1 month later...
    Posted · Support Settings for ABS cup with overhangs

    Thank you both @geert_2 and @Enigma_M4 for the suggestions! These are both excellent! @geert_2, I currently created a revised 3D model of my part with the support structure you suggested and hope to try it out soon on my printer. I'm currently fighting a couple of other, more basic ABS profile optimization issues that I need to solve before I come back to this one (See my post here). I will update you here with my results once I have had a chance to try a test print of it.

     

    @Enigma_M4. I tried your suggestion, but unfortunately, for this part, the bottom of the lip has to be flat in order for it to sit on the grinder holder. However, this is a great trick to keep in mind for other parts which don't have this requirement.

     

    Thank you!

    Jason O

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