What Is A 3D Printing 'Slicer'?

Posted by ORD on 26th Jul 2017

Ok, so I'm going to write a series of articles about the differences of slicers. People ask me this all the time so I might as well write it down so it can be referenced easily. But before I get to comparing I'm going to answer the question that many of you have "What is a slicer?". 

Yes I know that many of you have experience with 3D printers and know what a slicer is but so many people are coming to our web site or meeting us a maker fairs or trade shows and have no idea about how 3D printing actually works or what the process flow is. So let's keep this short and sweet. 3D printing has these main steps:

  1. Get a 3D model. This can come from any 3D design program like Fusion 360, Sketchup, Solidworks, Maya, 3D Studio Max, etc.. You could also download a premade file from Grabcad or Thingiverse, or Conversly you could 3D scan an object and turn the point cloud into an stl file.
  2. Slice the part. (We'll come back to this).
  3. Send the slice layer-by-layer to the 3D printer.

    Here's a visual representation of the process:

From Design to Create - The steps of 3D printing
You will notice that Simplify3D is in the Slicing and the Interface software processes. This is because it has both functionality in it to create the tool path and to communicate with the printer unlike Slic3r which is a standalone application that can only create the tool path.

Now back to what a slicer is...You've got a 3D model Like this V8 Engine:

3d printed model of a V8 engine

It's a solid 3 dimensional shape but the printer can only print 1 layer at a time. We have to break the model down into 2D 'slices' so that each one can be printed in sequence. This is what a Slicer is all about. It slices the model into layers and records the path that the nozzle of the printer must follow while it lays down the molten plastic.

Here is the engine all sliced up. Looks a little different than the 3D model above right?

Bigger 3D model of V8 engine for 3D printing

Here is what one of the more exciting layers looks like:

2d layer slice of v8 engine for 3d printing

Finally watch this flip show of each of the 2D slices in sequence. It's kind-of like stop motion animation. Each image varies by only a small amount since each layer must be built on top of the last. You can imagine as each slice is built up in sequence by the printer it will create the final 3D shape of the model:

Animated 3d printed 2d slice flip book of V8 engine

That's a pretty good primer on the purpose and function of a slicer. Each different program has their own algorithm for creating the tool paths that the printer will use. They also vary greatly in there feature set, and speed.

Next time I will go over some specific differences between some of the available slicers.