Tracking time has challenged the human race for centuries, resulting in some of the finest mechanisms ever crafted. From sundials and hourglasses to pocket watches and atomic clocks, we have marked the passage of time with ever-increasing precision. Along the way, we became supremely skilled at creating the requisite gears and springs, as well as the machines to produce them. (If you have a deeper interest in measuring time, one must-read book is Longitude by Dava Sobel.)
This post, however, is about taking clock-making to a new dimension – three dimensions, in fact, using multiple 3D printers to generate not only the gears and structural components but even the watch-spring and winding-key, based on a mechanism called a Tourbillon. Invented around 1800 by Abraham-Louis Breguet, the Tourbillon concept compensates for the effects of gravity on delicate watch-springs when the watch is carried or laid down (varying its orientations), by employing multiple axes.
Depending on one’s donation amount, some or all of the intricate clock’s CAD files are downloadable. Recently Justin Baxter, PADT’s senior 3D Printing Service Engineer (with years of hobbyist clock-making under his belt), set out to reproduce the device with a twist. Why not take advantage of all the additive manufacturing systems in use by PADT’s Manufacturing Division, and print at least one component on each?
This approach spans the AM technologies of Fused Deposition Modeling (Stratasys FDM material extrusion), PolyJet (Stratasys material deposition), selective laser sintering (3D Systems SLS polymer powder bed fusion), direct metal laser sintering (EOS DMLS metal powder bed fusion), stereolithography (3D Systems and UnionTech vat SLA photopolymerization) and digital light processing (Stratasys Origin One DLP vat photopolymerization).
The Triple-Axis Tourbillon Mechanical Clock Design
Not all of the clock’s 230 components are 3D printed – metal screws, pins and ball bearings round out the assembly – but Justin is slowly printing all other parts spread across colors, materials and AM technologies. For starters, he has recreated the central first-axis mechanism called the Mini Mechanica; this subset serves well for new users to test out their own systems and parameters ensuring effective dimensional tolerances. The Mini Mechanica part files are also available as a separate free download.
Justin’s Mini Mechanica includes the following parts made of ABS (acrylonitrile-butadiene-styrene), each 3D printed on one of our two Stratasys F370 FDM systems:
When finished, here is how that subset will fit into the completed three-axis clock:
Note: the fully printed clock operates on a 90 minute run-time if a steel spring is employed, and 20 minute run time with a 3D printed (FDM) version. (We’ve seen suggestions for adding a battery.)
As the part-builds progress across our other printers and materials, we’ll post an update. Here are a few more components in progress, including the decorative base on the left, which was printed in Nylon 12GS on our SLS powder-bed printer.
PADT Inc. is a globally recognized provider of Numerical Simulation, Product Development and 3D Printing products and services. For more information on Stratasys polymer printers and materialsand EOS metal printers, contact us at email@example.com.
While many examples exist of impressive texturing done on 3D
printed StratasysPolyJet printed parts (some
wild examples are here), I
have to admit it took me a while to learn that true texturing can also be added
to Stratasys Fused Deposition Modeling (FDM) parts. This blog post
will walk you through adding texture to all faces or some faces of a solid
model, ready for FDM printing. You, too, may be surprised by the results.
I know that complex texturing is possible in a graphics
sense with such software packages as Rhino,
PhotoShop, Blender and more, but I’m going to show you
what you can achieve simply by working with SolidWorks, from Rev. 2019
onwards, as an easy starting point. From there, you can follow the same basic
steps but import your own texture files.
SolidWorks Texture Options
First off, let’s clarify some terms. Texture mapping has
existed for years and strictly speaking creates a 2D “texture” or pattern. If I
were to wrap that imagery around a 3D CAD model and print it on, say, a PolyJet
multi-color 3D printer, I’d get a 3D part with a flat or perhaps curved surface
decorated with a multi-color “picture” such as a map or a photo of leather. It
could conform, but it’s still basically a decal.
A 3D texture instead is more properly referred to as Bump
Mapping (not to be confused with …..too late….bit mapping). Bump mapping interprets
the color/contrast information of a 2D image such that it renders light and
shadow to give the illusion of a 3D part, while remaining in 2D. Taking this
concept one step further, 3D CAD software such as SolidWorks can apply rules
that convert white, black and grey shades into physical displacements,
producing a kind of tessellated topology mapping. This new information can be
saved as an STL
file and generate a 3D printed part that has physical, tactile variations in
material height across its surface. (For a detailed explanation and examples of
texture versus bump-mapping, see the GrabCAD Tutorial “Adding
Texture to 3D Models.”)
For FDM parts, you’ll get physical changes on the outer
surface of the part that appear as your choice of say, a checkerboard, an
arrangement of stars, a pebbly look or a series of waves. In the CAD software,
you have a number of options for editing that bump map to produce bigger or
smaller, higher or lower, finer or coarser variations of the original pattern,
prior to saving the model file as an STL file.
Stepping through SolidWorks 3D Texturing
The key to making this option work in SolidWorks 3D CAD
software (I’m using SolidWorks 2020), is in the Appearances tab. Here are the
steps I’ve taken, highlighting the variety of choices you can make. My example
is the Post-It Note holder I described in my PADT blog post about advanced
infill options in GrabCAD Print.
Open Post-It note CAD file, select Solid Bodies
(left menu) and select Appearances (in the right toolbar).
Expand Appearances and go all the way down to Miscellaneous, then click to open the 3D Textures folder.
Scroll down to choose one of the more than 50 (currently) available patterns. Here, I’ve chosen a 5-pointed star pattern.
I dragged and dropped that pattern onto the part body. A window opens up with several choices: the default is to apply the pattern to all faces:
However, you can mouse over within that pop-window to select
only a single face, like this:
When you’ve applied the pattern to either all faces or just one or two, you’ll see a new entry in the left window, Appearances, with the subheading: 5-pointed Star. Right-click on those words, and choose Edit Appearance:
Then the Appearances window expands as follows, opening by
default to the Color/Image tab:
In this pane, if desired, you could even Browse to switch to
a different pattern you have imported in a separate file.
Click on Mapping, and you’ll see a number of “thumb wheel” sliders for resizing the pattern either via the wheel, clicking the up/down arrows, or just entering a value.
Mapping: this moves the pattern – you can
see it march left or right, up or down. I used it to center the stars so there
aren’t any half-stars cut off at the edge.
Size/Orientation: You can also try “Fit width to selection” or “Fit height to selection,” or experiment with height and width yourself, and even tilt the pattern at an angle. (If you don’t like the results, click on Reset Scale.) Here, I’ve worked with it to have two rows of five stars.
Remember I said that you can also make the pattern higher or lower, like a change in elevation, so that it stands out a little or a lot. To make those choices, go to the Solid Bodies line in the Feature Manager tree, expand it, and click on the part name (mine is Champfer2).
In the fly-out window that appears,
click on the third icon in the top row, “3D Texture.” This opens up an expanded
window where you can refine the number of triangular facets that make up the
shape of the selected texture pattern. In case you are working with more than
one face and/or different patterns on each face, you would check the box under
Texture Settings for each face when you want to edit it.
Here is where you can flip the
pattern to extend outwards, or be recessed inwards, or, if you brought in a
black/white 2D pattern in the first place, you can use this to convert it to a
true 3D texture.
I’ll show you some variations of
offset distance, refinement and element size, with exaggerated results, so you
can see some of the possible effects:
In this first example, the only
change I made from the default was to increase the Texture Offset Distance from
0.010 to 0.200. The stars are extending out quite visibly.
Next, I changed Texture Refinement
from 0% to 66.7%, and now you can see the stars more distinctly, with better
Finally, I am going to change the
Element size from 0.128 to 0.180in. It made the star edges only slightly sharper,
though at the expense of increasing the number of facets from about 24,000 to
26,000; for large parts and highly detailed texturing, the increased file size
could slow down slicing time.
To make sure these textured areas print, you have to do one more special step: Convert to Mesh Body. Do this in the Feature Manager by right-clicking on the body, and selecting the second icon in the top row, “Convert to Mesh Body.” You can adjust some of these parameters, too, but I accepted the defaults.
Lastly, Save the file in STL format, as usual.
At my company, PADT, my favorite FDM printer is our F370, so I’m going to set this up in GrabCAD Print software, to print there in ABS, at 0.005in layers:
You can definitely see the stars popping out on the front
face; too bad you can also see two weird spikes part-way up, that are small
bits of a partial row of stars. That means I should have split the face before
I applied the texture, so that the upper portion was left plain. Well, next
Here’s the finished part, with its little spikes:
And here’s another example I did when I was first trying out a checkerboard pattern; I applied the texture to all faces, so it came out a bit interesting with the checkerboard on the top and bottom, too. Again, next time, I would be more selective to split up the model.
NOTE: It’s clear that texturing works much better on
vertical faces than horizontal, due to the nature of the FDM layering process –
just be sure to orient your parts to allow for this.
Commercial aircraft companies are already adding a pebble
texture to flight-approved cosmetic FDM parts, such as covers for brackets and
switches that keep them from being bumped. If you try this out, let us know
what texture you chose and send us a photo of your part.
PADT Inc. is a globally recognized provider of Numerical
Simulation, Product Development and 3D Printing products and services, and is
an authorized reseller of Stratasys products. For more information on Stratasys
printers and materials, contact us at firstname.lastname@example.org.
Much as we
all love and use websites, YouTube videos and blog posts (you’re reading this
one, right?), there are still times when there’s nothing like a book, even if
you read it on your phone or dedicated device. Books provide data, perspective
and pointers to other resources, in a convenient, all-in-one format. You can
dive deeply into a subject or get a fascinating overview of topics you may
never have known were connected.
AM-lover on your holiday shopping list, consider one of the following titles:
by Ian Gibson (Author), David Rosen
(Author), Brent Stucker (Author) | Nov. 2014
NOTE: this was the first book written about
the field that I could find, with its first edition in 2009. (If you know of
one pre-2009, I’d be interested to hear about it.) SME uses this book as the
reference guide for its Certification exams for AM Fundamentals and AM
definitely exist that have more of a hobbyist focus. This list comes from my
own research and opinions and is not intended to slight any other titles. I’d be
interested in expanding the list if you know of other titles with an industrial