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I am going to design and build a 3D printer. I want the highest quality and accuracy so nothing except that is important for me. Which cartesian design has the highest quality and accuracy? CoreXY, Prusa, or Gantry (Ultimaker)?

Also, is it better to have a nozzle that moves in just direction "X", directions "X and Y", or "X, Y and Z"?

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    $\begingroup$ Every kinematic system can reach any quality, provided you spend enough money. You should define what are the constraints: cost? size of the mechanism? speed? $\endgroup$ – FarO Aug 6 '20 at 13:08
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Just to clarify: Examples of kinematic systems would be Cartesian (which includes CoreXY), Delta, Scara, and Six-Axis. The quality of the system has less to do with the system and more to do with the implementation.

Furthermore, there are 2 main types of desktop/benchtop 3d printers that are commonly available: Fused Deposition Modelling (or fused filament fabrication depending on who you ask) and stereolithography; of which the latter, stereolithography, has better accuracy and quality.

In terms of FDM however, it can be easily argued that CoreXY cartesian printers offer the best quality and accuracy (both of which are subjective btw) than either delta or gantry designs (e.g. gantry would be the Prusa i3). The reason is that in order to get the CoreXY to work at all, the overall engineering and frame rigidity must be at a certain minimum. Once this minimum has been achieved, the quality of the prints typically meets or exceeds the quality/accuracy of even a well-tuned gantry printer; and you are going to see it in the cost of a CoreXY printer.

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  • $\begingroup$ Direct Ink Writing or Robocasting is also available in desktop units. $\endgroup$ – Davo Aug 5 '20 at 20:27
  • $\begingroup$ Gantry is the Ultimaker style, not the Prusa. $\endgroup$ – Mahan Lamee Aug 6 '20 at 6:08
  • $\begingroup$ @MahanLameie An Ultimaker is also a Cartesian printer! :-) $\endgroup$ – 0scar Aug 6 '20 at 7:21
  • $\begingroup$ I know but if Prusa i3 is gantry, what is Ultimaker system called? $\endgroup$ – Mahan Lamee Aug 6 '20 at 7:33
  • $\begingroup$ Ok, I have alternative names for the styles based on how the bed moves, perhaps I should introduce them: I call the Prusa i3 style travelling beds because it travels back and forth. I call the Ultimaker style and all CoreXYs for that matter floating beds because they move up and down. Lastly, there is the static bed type which doesn't move at all. $\endgroup$ – user77232 Aug 6 '20 at 13:40
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The tradeoffs in these systems are all about quality achievable at particular speed and acceleration profiles. If you really don't care about speed at all and want maximum accuracy, you probably want some type of Cartesian setup with no belts, only rigid lead screws which you can take to as fine a pitch as you like, and you can make all the parts as rigid as you like because mass doesn't matter (since acceleration doesn't).

Note however that extrusion accuracy is the limiting factor to quality and dimensional accuracy in even a half-decent printer. Rather than trying to design something with "perfect" spatial kinematics for quality from the outset, I think you should look at existing printers, figure out what about them isn't meeting your quality needs, and start from there to improve. You should also figure out what your speed constraints will be, even if they're only minimal.

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  • $\begingroup$ So you mean that if I use belts, there is no quality difference between corexy and cartesian. right? $\endgroup$ – Mahan Lamee Aug 5 '20 at 11:12
  • $\begingroup$ If you go slow enough, there should be little if any difference. Cartesian (with moving bed) has more momentum to deal with in the axis the bed moves on. I guess in theory corexy has more belt length for belt to stretch along. It's definitely better at high speed/acceleration though. $\endgroup$ – R.. GitHub STOP HELPING ICE Aug 5 '20 at 11:18
  • $\begingroup$ As I said is it good for the nozzle to also move in z-axis in addition to x and y in corexy? Does it increase or decrease print quality? $\endgroup$ – Mahan Lamee Aug 5 '20 at 11:20
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    $\begingroup$ @MahanLameie Please note, a CoreXY is also a Cartesian printer! $\endgroup$ – 0scar Aug 5 '20 at 13:09
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    $\begingroup$ I think terminology usage differs. To me Cartesian means each of the X, Y, and Z motors directly controls an orthogonal axis. This excludes corexy. $\endgroup$ – R.. GitHub STOP HELPING ICE Aug 5 '20 at 13:22

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