When slicing models to 3D print, we have to balance two opposing factors: the speed of a print versus the quality of the finished part.

These factors are not always at odds; with advanced techniques, it is possible to reduce print time dramatically while still maintaining excellent quality.

In this blog, we will be using a pattern which might be used for sand casting or other molding applications.  These types of models are particularly well suited to FFF 3D printing, as draft angles and minimal overhangs make for trouble-free prints.

  1. Infill Percentage

I will start using the basic 3DP Workbench profile in Simplify3D and then explore techniques to optimize print time, starting with infill.

Print time on default profile (15% infill, .2mm layer height): 82 hours

We are all generally familiar with infill percentage (if not, check out Infill Percentage and Pattern Explained) , but may not be aware that infill may be kept very low, on the order of 10-15% for most common parts.  It can be tempting to bump up the infill percentage for a stronger part, however the benefit is minimal in most cases.

  1. Infill Pattern

The second setting to be aware of is infill pattern. There are several different infill pattern options, each with advantages and tradeoffs between print time, strength, and material usage. For example, Simplify3D provides six infill pattern options, including the most popular honeycomb and triangle infill patterns. The speed will vary only slightly, but honeycomb will save us a few minutes over Grid pattern.


  1. Layer Heights

The next step will maximize our time gains, if using small layer heights (.2mm with a .6 nozzle) we can direct our infill to print only every other layer (.4mm infill layer height).  This will cut our infill time in half, and will result in dramatic time gains for large parts like our test model. In the Infill tab of Simplify3D, change “Print sparse infill” to every two layers.


In the Infill tab of Simplify3D, change “Print sparse infill” to every two layers.


Notice how our infill (orange) is twice as thick as our perimeters (blue & light blue) This saves significant time; we are essentially cutting our infill time in half with no loss of surface finish.

  1. Maximum Allowable Speed

The final step toward optimizing infill is to ensure that the infill is running at the maximum allowable speed.  If we are using .4mm infill, we can run it safely at 70mm/sec.  Go to the “other” tab in Simplify3D, and set the infill speed to 100% (to match print speed of 70mm/sec).


set the infill speed to 100% (to match print speed of 70mm/sec).

Print time with infill optimized: 56 hours vs. 82 hours

  1. Multiple Processes

Once we have optimized our infill, we can leverage the power of multiple processes to change our settings as we build our part.

Set up two or more processes, in the Advanced tab, set process 1 to stop at a certain layer height, then process 2 to start at the same height.  After this initial setup, we can alter layer height and any other settings mid-way through a print.


set process 1 to stop at a certain layer height


process 2 to start at the same height

Once we have multiple processes set up, we can easily change the layer height and resolution of each process, optimizing speed for each area of the model. In our example, we print the base of the model with low resolution, fast layers.  When we reach our lettering we want a finer finish, so we drop the layer height down to .2.  The profile of the part when printed will look like this:


Notice how the layer height changes from .4mm to .2mm to preserve detail

In our mold example, we can print the base of the mold using thick, low-resolution layers without an issue, however when we get up to the text itself, we drop the layer height down to ensure our letters get a nice finish. Once the lettering is finished, we return to .4 layers for the remainder of the part.  This optimization takes a little time to set up, but it will save a good amount of machine time on larger prints.

Time of print with process optimization: 53 hours vs. 82 hours

There are innumerable tweaks we can make to our process settings, but starting with these two will result in significant time savings without any significant loss of detail.

save print time result

Source: 3DP Unlimited

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