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I want to print a thin and high cylinder (say, 1 or 2 mm radius and at least 2 cm high), and make it as strong as possible. Even with 100% infill, the layer-by-layer printing makes it rather weak. My idea is the following:

  • print the cylinder with 0% infill, only the walls
  • once this is done, place the nozzle on the top layer, right in the middle
  • let some filament flow inside the tube without moving the nozzle, until it's full

(for larger cylinders I would try some honeycomb pattern, and repeat the infill step until all cells are full)

My intuition is that, since the filament will end up in the direction of the cylinder, it should be much more resistant. Any thoughts? In particular:

  • Does this technique have a name? (Google isn't helpful without the right keyword)
  • Do Cura or others offer the option to do this automatically?
  • I can try to do it by hand with the G-code with some amount of trial and error... if anyone has any tips on the commands to use that would be helpful!
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  • $\begingroup$ If you want to print that small diameter pillars, you may want to look into buying plastic or aluminium rods, rather than printing them. It is very important to know waht the direction of the load on the pillars is. E.g. loading perpendicular to the height, or compressing or pilling along the length? Honeycomb in height direction is greaat for compression of the pillars, but of barely no use when bending the pillar. $\endgroup$
    – 0scar
    Commented May 15 at 14:44
  • $\begingroup$ It's mostly bending and torsion in my case, compression is not an issue. And yes an aluminium rod would be a good solution for strength, but in practice it's going to be a pain to find the perfect settings so that it fits nicely inside the pipe $\endgroup$
    – tarulen
    Commented May 16 at 7:33

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With one to two millimeter radius, two to four millimeter diameter, you're limited to the number of nozzle-widths when using a typical 0.4 nozzle. Two concentric circles generates a 0.8 mm cylinder, while better results may be had with five circles for a 2.0 mm cylinder.

Creating a cylinder and "filling" the 2 cm tall opening is not going to be practical, as the filament will cool before it reaches the bottom. Periodic filling is effectively the same as normal layer-by-layer printing.

Addressing your suggestion of custom g-code, you may find useful the FullControl GCODE designer, a free parametric creator program. One must have a solid grasp of some programming, in my opinion, as the parametric aspect requires, well, parameters to be entered to create the desired objects.

This software was used to create the pin test for 3D printers, an extremely narrow cylinder on which a sphere is generated. That code alone, the pin build, may be enlightening for your objective. One example can be found on Printables. The creator references a different website that is the same program. Image from Printables site:

3D printer pin test

I think it's important to note that regardless of the method used, you'll not get a particularly strong cylinder. In cases where I desired more strength, I flattened a portion of the cylinder along the length and printed it flat. In other cases, I split it in half and glued the pieces together. Those results were superior to vertical printing.

One last suggestion. If you create a vertical print, be advised that you'll get insufficient cooling if you are printing one item. Consider to create a toss-away model that takes two to four times the duration to print a layer as the original cylinder. This will give the objective time to cool and better accept the next layer. Another method is to print multiples of the small cylinder which accomplishes the same thing, as long as the alternating layers begin at the same location.

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  • $\begingroup$ Thanks for the advice! Yes horizontal printing is best obviously but then attaching parts together can pose other issues. (e.g.in the pin sample you gave, I'm not sure a dot of glue would be strong enough between the base and the pillar....?). I'll look into the gcode designer now:) $\endgroup$
    – tarulen
    Commented May 16 at 7:38

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