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I have an STL (Raspberry Pi 4 casing) that automatically places itself like below on the bed surface:

enter image description here

Would it be a better and more efficient print if I place it like this:

enter image description here

At first, I thought this is no-brainer, the bigger surface should be the bottom layer. However, the horizontal print might result a more efficient head movement.

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  • $\begingroup$ I do not understand the use of "However", at first you conclude to print the casing as in the second image to mention that the horizontal print (second image) may result in more efficient usage (didn't you mean vertical instead of horizontal). Could you elaborate on that part of the question by edit? $\endgroup$
    – 0scar
    Sep 23 at 8:20
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    $\begingroup$ @0scar - I think he means the vertical print (i.e. with the model standing on its end, rather than laying flat)... in that case, "however" makes sense. It's a strangely complex situation (i.e. the two different orientations) to clearly put into words... maybe "At first, I thought this is no-brainer, the bigger surface should be parallel with the X-Y plane. However, standing the print on its end (with the larger surface parallel with the Z axis) might result a more efficient head movement." is a better way of phrasing it..? Unless I have misunderstood the premise of the post. $\endgroup$
    – Greenonline
    Sep 23 at 15:13
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The second placement is a better choice from an overall standpoint. In the vertical placement, adhesion is going to be more critical, although Prusa printers have good bonding for PLA and ABS, from my direct experience.

The other aspect of more importance is that the holes are going to be distorted in the vertical arrangement. The cut-outs in the smaller portion will also "droop" unless otherwise supported. If supported, you'll have greater post-processing labor and unsightly surfaces.

The design is quite well done, as the corners have radii which allows for smoother carriage travel, rather than abrupt stops with direction changes at each end.

Importing the model and having the result appear as in the first image means that the designing software swaps the z-axis and the y-axis, which is relatively common.

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    $\begingroup$ The more overhang is eliminated the better the print. $\endgroup$
    – Perry Webb
    Sep 23 at 17:38
  • $\begingroup$ Distorted holes aren't always a problem: I've used the distortion to improve the grip of whatever's being put in the hole. $\endgroup$
    – Mark
    Sep 23 at 21:55
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You've already got the correct answer, but I want to address an additional misconception in your question: head movement efficiency. Most 3D print jobs are acceleration-bound, not top-speed-bound. Without really cranking up the acceleration limits (which requires Klipper and input shaper tuning), the head will only reach the requested speed on long linear moves.

The orientation lying flat has a lot of those: the 4 sides are all long, and the diagonal fill line are long.

The orientation with the part standing up on one end has very short lines, and a lot more of them.

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Long story short, laying the design horizontally is a lot less problematic when compared to laying it vertically. I'll explain:

[ Vertical ]

  • Bridging becomes more of an issue with the edge overhang. You'd need stilts to support the overhang which would fill the entire inside of your case.
  • Wear on the printer is a concern because of the short travel distance. You'd have to print along the grain which would result in a structurally weaker design.
  • Holes are very difficult to do vertically and may need to be cleaned up afterward.
  • Excess heat build-up from the printer head may be an issue due to it having to stay in the same area for longer, which may cause problems like melting or sharp hooks/spurs.
  • Vertical clipping is more of a concern as the printer head has more of a chance of knocking over the design (thus ruining the print and wasting time/materials). Also, less surface area for adhesion for the first layer means the design is more prone to falling over.

[ Horizontal ]

  • Bridging is a lot less of an issue other than the cable/power porthole on the side of the design.
  • Wear on the printer is a lot less of an issue because of the longer travel distance in either direction (printing with the grain or against)
  • Holes are much easier to create when laying horizontal.
  • Few changes to build up heat resulting in your print being more consistent, not warping or melting.
  • Low clearance and large base level surface area make it near impossible for the printer head to clip/catch and ruin the design.

In most cases, it's best to keep your design as low and spread out as possible, though I've had some prints where that wasn't an option.

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  • $\begingroup$ Welcome to 3D Printing SE and thank you for your contribution. When you get a chance, please take the tour to understand how the site works and how it is different than others. $\endgroup$
    – agarza
    Sep 23 at 16:43

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