I'm working on a project where I have to design a Cartesian 3D concrete paste printer, in which I aim to make the build plate fixed with a 500 mm × 500 mm build area. But I'm confused as to how I should implement the motion of the Z-axis. I am thinking between:

  1. Using a Z-axis that moves the entire X and Y frame.
  2. Using an independent Z-axis that moves by itself only without the X and Y frame.

What are the differences between the two methods in terms of:

  1. Performance
  2. Ease of design & assembly
  3. Cost

What design is more reasonable from a mechanical design point of view?

An example of the first method is the TITANXY (Fixed Build Plate, Quad Z Screw, CoreXY)

An example of the second is the Maximus 3D Printer


1 Answer 1


Both are viable.

There are classic CoreXY printers where the extruder is moving along a gantry that slides along two rails which are moved up and down by four vertical lead screws in the corners. It's a lightweight construction suitable for very fast printers - with bowden tube feed (extruder far away from the hot end) the print head can be very light; some smart belt management allows to keep both X and Y motors only move up and down, which allows for extreme accelerations in X,Y directions, only Z is slow - and it rarely needs to be fast.

Then there's the design where a fixed gantry - be it a bridge over the table, or a beam moving on fixed rails up above the table - moves horizontally, and you have a carrier attached to it, which can move along the gantry, and move a Z slide - a vertical beam with the head at the end. This is used more frequently in CNC mills, as the construction can be made much more sturdy and rigid, but since the carrier hauls two stepper motors and a heavy spindle around, the accelerations achievable aren't as high.

The two are fairly similar in terms of ease of design and assembly. As for performance, the former performs great for lightweight, fast work. The latter is great where you need force, torque, e.g. you use a specialized material with a heavyweight extruder - like for the concrete paste maybe?


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