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Optimizing Your CAD Software for FDM 3D Printing

Whether
modeling in SOLIDWORKS, Creo, NX, or any other Computer Aided Design (CAD)
software, bringing your design to life is easy with a 3D Printer,  but it all starts with an STL file.  Here are some tips to consider for your next
design, to get the best possible 3D Print, while reducing material waste.
CAD
First, watch the walls. The
width of thin walls should be designed as a multiple of the filament bead
width, bearing in mind the number of perimeter toolpaths (aka “contours”).  For example, the standard configuration for
Stratasys professional 3D printers produces one 0.5mm perimeter bead (with
infill rasters in between).  Very thin
walls should be either 0.5mm OR 1mm wide.
Any width in between is likely to be undersized and/or inconsistent.
Next, mind the gaps. Most
machines (or slicing software) have a minimum size for infill rasters, which
might result in airgaps within thin walls.
For the example machine above, a 1.3mm wall isn’t quite wide enough to
infill, so it’ll print as two thin flimsy walls side by side.  In this case, a 1mm wall would be more rigid,
despite being narrower, because the two beads would be fused.
Also
be sure to remember that STL files (sometimes referred to as “Standard
Tessellation Language”)
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are faceted; meaning they contain no curves!  So, when sliced into layers, every 'circle'
is actually a polygon.  Thus, exterior
curves will always be slightly oversized and internal curves will be slightly
undersized.  The results can be improved
by tweaking the STL export settings in CAD (use the “fine” resolution or
better); just be consistent.  While
designing, consider defining custom oversized hole standards or undersized
library features, in order to get consistent fits for pins/holes.

 

Last
be sure to take into account orientation. Whenever possible, build cup-shaped
parts open-end-up, to avoid unnecessary support.  But when that that’s not possible, consider
that most machines can bridge short horizontal spans without building support
underneath.  To minimize use of support
material and speed up prints, stay out of the ‘support zone’ between 0°
(horizontal) and 45°.  Also include
chamfers or fillets to inside corners whenever possible, to reduce the length
of horizontal spans (and the likelihood they will require support).  For example, a 1” diameter cup printed
upside-down might result in a LOT of support material used.  But adding just a 1/8” chamfer reduces the
unsupported “ceiling” to just ¾”, and might eliminate the need for support
altogether.