3D printing is a topic that’s in the forefront every designer and engineers mind nowadays. The ever increasing array of technologies and cost effective solutions available on the market, mean that the option to use prototyping equipment to prove a design is more readily available to us than ever before. So once we`ve used SOLIDWORKS to finalise those last design details, how do we successfully make the transition from SOLIDWORKS to a 3D printed model?
From SOLIDWORKS to Prototype-
Preparing your model for 3D Printing
3D printing is a topic that’s in the forefront every
designer and engineers mind nowadays. The ever increasing array of technologies
and cost effective solutions available on the market, mean that the option to
use prototyping equipment to prove a design is more readily available to us
than ever before. So once we`ve used SOLIDWORKS to finalise those last design
details, how do we successfully make the transition from SOLIDWORKS to a 3D printed
model?
STL files
STL files are widely accepted as the industry standards when
it comes to rapid prototyping. It is the one single format that can be output
by most CAD programs that can be understood by the vast majority of prototyping
equipment.
So what is an STL
file?
STL or Standard tessellation/triangulation language is a 3D
file format which uses a series or triangles to describe the outer surfaces of
a 3D model. There is no colour, texture or additional attributes i.e. features.
How do I create an
STL file?
This is really easy. With your part (or assembly) opened
inside SOLIDWORKS simply click file>save as to open the usual save as
window. Then use the drop down to select .stl from the list.
This method of saving a .stl file will generate the file
with the default resolution settings. However these settings may not suitable
for your printer and could have a negative effect on the quality of your 3D
print, so you should consider if you need to make any changes to ensure you
have the correct settings.
What are these
settings and why do we need to control them?
I like to think of these settings as “resolution” or
“accuracy”. In simple terms, if you consider the idea of converting a perfectly
round sphere (which is your SOLIDWORKS model) to sphere constructed of
triangles (your .stl file). The bigger the triangles the coarser the resolution
of your .stl file and vice versa. We
have the ability to control how these triangles are created when the .stl file
is generated, so we choose how coarse or fine the model is. But why? There is one main reason why
we should think of controlling these settings, and this is because it can have
a direct effect on the quality of your printed 3D model. If your settings are
too course compared with the resolution of your 3D printer, then the printer
will be able to print the definition of the triangles and your model will
appear faceted, deviating away from the shape of your intended design. If you
set your model too fine, although you won’t suffer from poor quality models,
the likelihood is that you will have a large file that takes a long time to
process and can be more difficult to
handle.
So how do we control
these settings?
In the save as window, once you’ve selected .stl as the save
as type, an options box will become available. Click options to adjust the
settings
ASCII vs Binary
You have the option to save STL files in either binary or
ASCII format. Binary files are smaller (by a factor of 6!), so this format is
usually preferred. However, ASCII files can be visually read and checked.
Resolution settings
Within the resolution settings there are two default options
(coarse and fine) as well as a custom option. Depending on the printer
resolution, it may be the case that the coarse and fine options are too close
to either end of the scale to be practical. Choosing the custom option will
allow us to control the resolution to be exactly what we need.
We have the possibility to control both the deviation and
angle of the triangles during .stl conversion. Deviation is expressed as a
linear dimension and refers to the maximum distance that the facet of the .stl
file is permitted to be away from the original geometry. The angle setting
refers to the angular deviation allowed between adjacent triangles.
The image below illustrates how different resolution
settings can affect the converted model. Taking number 1 as the intended design
(SOLIDWORKS model) and number 3 as the best possible resolution 3D printed model.
Setting a coarse resolution (Number 2) will mean that the printer, having a
finer resolution will be able to physically print the facets, leaving you with
an un-accurate model with visible facets. Choosing a very fine resolution
(Number 4) means that the file may be overly large, difficult to handle and
will almost certainly take longer to process than necessary. Number 3 in this
case is the optimal resolution. The settings made in SOLIDWORKS match that of
the printer, meaning the best possible 3D printed model and the most efficient
in terms of file size, handling and processing.
Which settings should
you choose?
This all depends on the resolution of the printer you’re
using. Because there are so many printers to choose from these days, my best
advice would be to take a look on the manufacturer’s website where you can
normally find advice on the best resolution to choose.
Don’t forget with windows 8.1 and SOLIDWORKS we can now
print directly from SOLIDWORKS!
http://www.SOLIDWORKS.com/sw/products/3d-cad/print-directly-to-3d-printers-3mf-and-amf-formats.htm
Nick Jones
Applications Engineer