Before printing anything you obviously need to design it. You have to draw/model a "solid". An enclosed "volume" (as if you were to pour resin in it). A single line or a basic surface "do not exist" (because they lack any thickness). Once your model is good - or you've downloaded a suitable model - you then move to the slicer.
A slicer will take the model (typically as an STL file which describes stuff a simple geometries) and slice it into many layers because that's how consumer 3D printers work (FDM). Lots of settings to tweak although most software have pre-sets that give good results.
At that point you can usually scale, mirror parts (or you could do it in you 3D modelling software before exporting to STL).
Then you have to decide how thick layers will be: 0.05 to 0.2mm. Thinner layers may give better details but will take much more time. Thicker layers can yield stronger parts.
Then you have to specify the "fill rate". Let's say you want to print a simple cube. Either you could tell the slicer to fill it 100%. Printer would then print layers after layers of plastic until you have a solid cube.
Or you could tell the slicer to fill it only 20-25%. Once a solid "floor" is printed (0.6-1mm) only a perimeter wall (0.8-1mm thick) will be printed and the void will have a simple grid or honeycomb "filling" that will save time, material and weight.
That's a 50mm cube. Layer height and print speed are the same. Printer head path is show in yellow. Both screenshots show the same layer (somewhere near the middle of the cube). First screenshot is with 100% fill rate (ie: "solid cube") while second screenshot show 20% density.
Not the difference in print duration and amount of material in the upper left corner. Significant !
Another important aspect is whether support structures are needed. As you know FDM printer is actually a pastry bag moved around by stepper motors.
This leads to an obvious issue: where does the icing go when there's no cupcake under it ? Or : how can I print a bridge or any other opening or cantilever in a model ?
Short answer is: you can't. That why you might sometimes need to add support. Some extra material added by the slicer to support the print and that will be discarded when the print is completed. You may rely on the slicer or on a different pre-processor.
Long answer is: depending on the material you can - to some extend - print in the void or at least "bridge" over a few millimeters or even a few centimeters. Some material are better than other (ie: material with a very fast "glass transition").
Changing the orientation of the model can help (printing sideways, upside down ...). But sometimes it is much more efficient to split your model in 2 or 3 pieces and glue them back together once printed. It is tempting to print a whole model at once but that's not always the best method.
Orientation will also dictate how the part perform strength-wise. 3D printed parts don't like shearing parallel to the layers (you might end up with delamination under stress). But if you know how the part will be stressed you can printed at the right angle so that pressure is applied 90° to the layers.
3D printing is still more akin to milling/machining. Quite a lot of settings to play with depending on the model, material ... ABS for instance tends to retract when cooling down. Parts tend to pop off the build plate and then warp. You sometimes have to add extra tabs/extra surface at the base to try and prevent this.
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Topic: My 1st 3D printer (Read 22375 times)