2. AGENDA
1. Introduction on FDM and AM
2. Geometrical constraints
3. Support structures
• Avoiding support structures
• Working with support structures
4. Hollowed parts and infill
5. Printing text
6. Designing mechanisms
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3. FUSED DEPOSITION
MODELLING
• Additive Manufacturing (AM)
technologies build parts by
overlapping layers of
material
• Extrusion of melted material
through a nozzle on a build
plate
• Cartesian coordinates
• Tolerance (in vertical
direction) is determined by
the diameter of the nozzle
• Examples:
Stratasys, RepRap, Ultimake
r
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4. WORKFLOW
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Design a part Export to STL Check STL
• CAD program • All packages can • Netfabb
do it
6 5 4
Start printing! Upload Gcode Slice and
• Ultimaker’s to printer generate Gcode
controller • SD card • Cura
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5. MATERIAL PROPERTIES
• Ultimaker uses 3mm PLA
PLA filament Polymer
• Biodegradable Physical property
thermoplastic Specific Gravity [g/cm3] 1,25
Melt Index [g/10min]
• Highly anisotropic (190º/2,16kg)
4-8
mechanical properties
• Several colors available
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6. GEOMETRICAL
CONSTRAINTS
Minimum Wall thickness:
• Vertical and tilted walls:
• 2mm and above. Recommended
• Horizontal walls:
• 1mm and above is correct
Definition 0,5mm minimum details noticed
Accuracy 0,3% (min +/-0,3mm)
Avoid warping Large horizontal and thick surfaces are
likely to warp, skip using them if you can.
Overall maximum dimensions 150*150*150 mm (x*y*z)
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7. FACING GEOMETRICAL
CONSTRAINTS
• Scale parts
• After scaling check that your part meets the geometrical
constraints
• Notice that wall thicknesses will be scaled down as well, and
may not meet the requirements
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8. SUPPORT STRUCTURES
• Support structures are
features added below
part areas where
there’s nothing
• They prevent layers to
collapse during it’s
build up and allow
part manufacturability
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9. AVOIDING SUPPORT
STRUCTURES: PART ORIENTATION
• Part orientation is a key
factor to achieve a good
print
• In many cases we can
avoid or at least reduce
the amount of supports
required
• Resolution is better in the
z-axis faces (vertical) than
XY (horizontal)
stepping
• Mechanical properties are
better in the XY plane
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11. AVOIDING SUPPORT STRUCTURES:
SPLITTING PARTS
• Splitting parts is a good way
to avoid using supports
• Can be done after exporting
the CAD to STL by using
Netfabb
• To use in extreme causes
because:
• We’ll have to glue all the
parts after the print
• Tolerances will not be the
same
• We’ll see partition lines in
our part
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12. AVOIDING SUPPORT
STRUCTURES: MODIFY
OVERHANGING SURFACE
• The printer is able to print
overhanging surfaces
without support structures
from a minimum angle
α (>30º)
• We must do the
modifications before
exporting the STL file
• Small projections from the
walls (<1mm) can be
printed without problems
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14. AVOIDING SUPPORT
STRUCTURES: BRIDGES
• The printer is able to Bridge
print flat surfaces
without supports
between two walls
• Max distance between
walls: 20mm
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16. WORKING WITH
SUPPORT STRUCTURES
• Accessibility: We must be
able to remove SS easily
• Scaring: Avoid using them
in part characteristic
surfaces SS can
damage the finishing of
these surfaces and also
the tolerances
• Avoid using SS below thin
walls or slender and
fragile parts, they can
break easily while
removing them
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17. HOLLOWED PARTS AND
INFILL
• Hollow can be achieved when gcode is generated, by
changing parameters of Cura
• We can also choose how much infill (%) we want inside the
part, by default we use between 30% and 40%
• Design Tip: design always solid parts
Infill
Perimeters
Gcode Cura View
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18. HOLLOWED PARTS AND
INFILL
By reducing the infill:
• Build time decreases
• Used material decreases
• It helps to avoid warping
• Strength doesn’t decreases
that much
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19. PRINTING TEXT
• Text in vertical faces will be
more visible and accurate
• If it’s not possible, the text at
the bottom of the part (the
face that sticks to the building
platform), must be engraved.
• In the top face of the part, text
can be either
engraved/embossed
• It should be at least 0,8mm
high and 0,8mm wide to be
visible.
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20. PRINTING TEXT
Vertical embossed text
Horizontal engraved text
Vertical engraved text
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22. DESIGNING
MECHANISMS
Part orientation
• Try to print the areas of parts that has to fit
each other in the same orientation (different
orientations could have different
deviations/tolerances)
Integrated nut holders embossed is better
than engraved!
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