Printing Guide
Revision 1.3
Kudo3D Titan 1 – Printing Guide
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Copyright © 2015 by Kudo3D. This material may be distributed only subject to the terms and
conditions set forth in the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0
International License or later. The latest version is presently available at
http://creativecommons.org/licenses/by-nc-nd/4.0/.
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Version
Ver. 1.0
Ver. 1.1
Ver. 1.2
Ver. 1.3
Description
Initial version
Printing and Post-Printing Updates
Printing and Post-Printing Updates
Printing Updates
Date
12/20/2014
1/4/2015
1/12/2015
1/18/2015
Preparing a printable 3D stl file is vital to achieve a high quality 3D print. If you design
your own 3D models, you may skip step 1.
1. Locating 3D models online
There are many websites that provide a variety of 3D files that you can download for free.
If the file format is not an ‘stl’ file, please use a software to convert the model into an stl
format. Thingiverse (http://www.thingiverse.com/) is our preferred site because a
majority of the files are in stl format and are provided for free. We recommend 3D
models with higher resolutions to avoid limitations posed by the 3D image itself.
2. Diagnosing and repairing files
All downloaded 3D files need to be checked before hollowing or slicing. Some files may
even need to be repaired. Use netfabb Basic
(http://www.netfabb.com/downloadcenter.php?basic=1) to check your STL files ensuring
the following 3 factors:
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The surface of all objects maintains an “outside” orientation (facing/pointing
outwards).
The surface of all objects is fully closed. Every object is comprised of many
triangular surfaces. Sometimes there might be a triangular surface missing on
an object so the entire surface of the object is not fully closed.
It is best for objects to have as few shells as possible. The ideal situation is to
only have 1 shell. Multiple shells could result in a problematic model after
hollowing or slicing.
netfabb Basic ensures the integrity of the 3D models. Use netfabb Basic to view and
diagnose stl files for any errors. If problems are detected, please use netfabb Cloud.
netfabb Cloud can be used to repair stl files and is able to solve issues relating to the 3
factors mentioned above all at once. It repairs 3D models in order to have the right
orientation, to close the surface, and to minimize the number of shells. Please login to
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netfabb Cloud (https://netfabb.azurewebsites.net/) with your Microsoft account and
upload the stl that needs to be fixed.
Both netfabb Basic and netfabb Cloud services are provided for free.
3. Hollowing 3D models if necessary
Most 3D models require hollowing to save printing materials. In addition, hollowing
minimizes light exposure areas and greatly reduces layer separation force. The printing
time is thus shortened and the printing quality is enhanced.
Opening a venting hole at or close to the bottom of the hollowed model is required to
avoid vacuum force during printing. Make sure to minimize the number of shells in your
model with netfabb Cloud to ensure proper hollowing.
We use “Meshlab” to hollow our 3D models by building a smaller offset model with an
inverted surface. Meshlab provides many functions, but we recommend using it only to
hollow models. netfabb Basic also can be used to check if a model is hollow or mesh.
Please refer to the following link for more information on how to hollow a model:
https://sites.google.com/site/3dprintfaq/workflows/hollowing-a-model.
4. Arranging layouts
We recommend arranging layouts in “Creative workshop” (download link below);
however, you can use other free software for the same purpose. Layout in Creative
Workshop has a “3D view” tab. Within this tab, perform the following steps:
1. Import all models to be printed to “Creative workshop”. Multiple models can be
included to be printed at the same time.
2. Resize, reorient, mirror, and reposition the models within the build boundary.
3. Place the models on the floor if there is no need to add support.
4. If you need to add support, lift the models at least 2 mm (small prints) to 2.5 mm
(large prints) above the floor. Refer to step 5 for further information on adding
support.
5. Save the layout to a new file.
Note: Models cannot be edited at this stage.
Creative Workshop can be downloaded at http://www.envisionlabs.net/.
5. Adding support if necessary
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Adding support is subjective and discretionary. Some models may not require support if
they have a large flat bottom and no regions pointing downward. Others may require
different types of support to ensure model integrity during the printing process. Here are
some rules of thumb for adding support:
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Locate all surface areas with local minima (upside-down hills or tips).
Determine the number and location of supports that must be added on downsidefacing areas to maintain mechanical stability of partially printed models during
printing.
Determine which supports should be built from the floor or on the model itself.
If possible, add supports to areas that are not visibly important.
Add supports that are strong enough to ensure that they do not bend during
printing.
Make sure the tip of the support is strong enough to prevent the printed model
detaching from the supports during printing. Longer supports may need to be
thicker while shorter supports can be thinner.
Make sure the tip of the support is not too large, which can leave scars after
removal.
When printing symmetric, thick objects, shrinkage of the resin may cause the
object to fall off the build platform. Using attachment layers and supports will help
the object stick to the build platform. There will still be shrinkage as the support
structures will be bent and squeezed; however, the printed object will stay
attached to the build platform.
There is no software that is intelligent enough to add automatic support without human
judgment. The only time that automatic support may work is if the print has a flat surface
or if the slope is very small.
We recommend using Creative Workshop (download link in step 4) to generate basic
manual supports. With Creative Workshop, you can specify position and the width of the
tip, middle, and bottom sections of each support. To create a new support, click Menu,
then Generate Support, and the next support structure will appear. Once the support is
selected, hold the Shift key, and use the cursor to move the support. The height of the
support will adjust automatically. In the 3D view, rotate the model to check if the
supports are in the right positions.
Occasionally, supports must stand on the surface of the printed model itself rather than
the floor. One example would be supports for the chins. Because Creative workshop
only allows users to generate support that touches the floor, you will need to export the
model with the supports from Creative workshop to an editor, such as “Blender”, to add
additional supports. Once the additional supports are added, export the revised model to
a new stl file and check the integrity of the revised STL file. Alternatively, you can
upload the model with supports to “netfabb Cloud” before slicing.
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6. Slicing
The principle of 3D printing is based on an additive process of building physical models
by attaching multiple thin layers. In order to generate those thin layers, the computer
generates 3D models that need to be sliced into layers of 2D images before printing.
Build area and the thickness of layers are two main parameters used to determine
printing resolution. You can set these parameters with any slicing program. Before
slicing, name your printable stl file in an “ABCD_1234.stl” fashion; other formats may not
be readable by the slicing program. Once the file is uploaded, specify the resolution
information using numbers.
After slicing, please open the folder that contains the saved 2D image files and check
the layer images for [insert]. For models with complicated surfaces, you might find
layers missing supports.
Supports may need to be added on local minima (upside-down hills or tips). Use the 3D
viewer to look for these local minima. You can find missing supports by reviewing the
slices layer by layer. Missing supports can be identified by white dots that are not
connected to any other slice. You can fix the slices with “Paint” directly. Alternatively,
you can fix the printable model with “Blender”, diagnose and debug the file with “netfabb
cloud”, and then slice it again. Zip all images files except for layer 0 to a zip file in the
“ABCD_1234.3dlp.zip” fashion.
7. Printing
To enhance the printing quality, increase the success rate of printing, and extend the
lifetime of the PSP resin container, it is helpful to understand the separation force of the
resin and try to reduce the force as much as possible. Please refer to the following tips
regarding separation force:
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Separation force is nonlinear and is higher in the beginning of the peeling
process. In other words, separation force is higher in the region closer to the
linear stage module.
Separation force increases as lifting speed increases.
For the first 1.2 mm of printing (using the large build platform with low viscosity
resins), the separation force is dominated by a vacuum force that pushes two
parallel plates together. The seperation force depends on the resin viscosity, the
size of the gap, and the area of the parallel plates.
Hollowed models must be vented with holes close to the base to prevent vacuum
force.
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Symmetric geometries usually have a higher separation force. If possible, please
break the symmetry by reorienting the model to be printed. Pick a direction to tilt
the model using Creative Workshop and add any necessary supports.
Repeated patterns (solid prints such as round or rectangular objects) may create
additional separation force due to semi-cured resins laying in the same place.
Reorienting and/or tilting the model can alleviate this effect.
Shrinkage may cause the cured layers to turn into a bowl-like shape that could
induce a suction cup effect. For example, if you print a flat disk, it might be
printed as a ball shape, because of shrinkage.
In general, layers with larger pattern area have higher separation force. Reorient
the model to reduce the pattern area.
Resins have a stronger bond the longer they are cured. We recommend curing
the first few layers longer (having longer exposure time) to ensure that the
printed model bonds to the build platform. We recommend lowering the exposure
time for subsequent layers. If the exposure time too long, the resin can stick to
the Teflon, which can drastically increase printing time.
Some resins have stronger adhesion to Teflon than others.
In addition, here are some general printing tips:
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Make sure the build platform is parallel with the resin container.
Make sure the zero position is where the build platform touches the resin
container without a gap.
Inspect the bottom of the resin container and the projector lens surface. Use
cotton swaps or a dustless cloth with IPA (Isopropyl Alcohol) to clean up anything
that can block the optical path between resin container and resin container.
Calibrate the required focus and resolution (projected area) with the red
calibration grid.
Insert the lens stop and make sure the focus is not altered after inserting the lens
stop.
To print fine pillar structures, overexposure of resins is necessary to ensure that
the pillar is strong enough to resist separation force.
To print structures with tiny holes, resins with less viscosity are needed. Make
sure to not overexpose the resin.
We highly recommend including a large 0.3 to 0.4 mm attachment layer (base)
for all models to ensure the print adheres to the build platform. This thin base
can be added to the model before slicing. Alternatively, the first few sliced layers
can be replaced with large area rectangular layers. Exposure time for the first
attachment layer is usually 10 times the exposure time for the regular layers.
You can decrease the exposure time for the subsequent attachment layers. We
normally set the printing speed to 25 mm/min for the attachment layers. If
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you are using a very sticky resin, you may want to decrease the speed even
more.
Rings require multiple supports and attachment layers. The ring stands on the
supports and the supports stand on the attachment layer. For rings, import to
Creative Workshop and lift at least 2 mm (Z) above the floor.
Due to the limitations posed by the projector lamp and optics, the brightness and
resolution across projected images is not uniform. The intensity is slightly higher
in the center and the resolution is lower at the four corners. Therefore, if you
want to utilize the area close to the edge of the projected image, you would need
to overexpose the area to make sure there is enough curing.
To maximize the printing speed, exposure time and lifting height should be
minimized while lifting speed should be increased. However, the print will fail if
these parameters are overdone. Iterations of experiment are required to
optimize the printing parameters. Always start with a more conservative set of
parameters for the first print as a base line.
Please select an appropriate type of resin to fit your application.
Pour in at least 60 ml of resin into the resin container. If the solid volume of the
model is greater than 50 ml, you will need to add an additional 20% of the
required resin. Please check the volume of the model to be printed with “Netfabb
Basic” before pouring resin in the container. If the printer is not leveled, the
resin will tilt to one side and additional resin will need to be added.
Exposure time can be calculated and estimated using the projected area. The
bigger the projected area, the lower the intensity of the projected light. In addition,
exposure time needs to be increased in order to cure the projected area. As
projected area increases, exposure time will also need to increase.
For better resolution, it is recommended to minimize the projected area while
maintain an area larger than the printing area.
In general, Z layer thickness corresponds to the XY resolution.
If you are printing an extremely smooth slope and feature thickness, use a
smaller Z layer thickness than the XY resolution.
Please make sure the display is not disturbed during the printing process. Please
disable any potential interferences, such as antivirus scanning, screen savers,
and hibernation/sleep modes.
To tune the printing process, stop the print and modify the parameters. Press
“run” and set the “Begin Layer no.” to the next layer from where you left
off. Please remember to export the updated parameters to a new excel file for
future reference.
If the cured layers do not stick to the model and only one or two layers dropped
before you notice, stop the print immediately. You may be able to save the print
with a much longer exposure time for the next layer and also slightly increase the
exposure time for the rest of the layers.
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If the cured layer is separated and only one or two layers were printed before you
notice, stop the print immediately. You may be able to save the print with a much
longer exposure time for the next layer and increase the lifting height for layers
that may not have enough lifting height.
If the supports tend to break or bend during printing, increase the exposure time
for the supports. If this does not work, increase the diameter of the support.
Do not use a thick solid base since shrinkage may peel the model away from the
platform.
Do not print a big solid model as the model may crack.
Shrinkage is positively correlated to the bulk volume. Therefore, hollowing the
model will lower shrinkage while minimizing the exposure area with less
separation force. However, we recommend a minimum wall thickness of 1.5
mm.
If the resin container drops before reaching your programmed lifting height, you
can lower the lifting height to speed up the printing.
For high-resolution prints, the printer should sit on a sturdy table that does not
vibrate.
Hide venting holes for hollowed models in areas that are not visible. The holes
must have a minimum diameter of 2 mm. The number of holes depends on the
size of the model.
Printing is not sensitive to tiny dust particles. However, larger dust particles on
the lens and at the bottom of the container will need to be removed.
Please do not look into the projector lens directly.
Do not overfill the vat. During the early stage of printing, the suction force will
remain until the build platform is lifted above the liquid resin. The suction force
decreases as the gap between the build platform and the Teflon film increases.
Shrinkage depends on both the base resin and the pigment used. Therefore,
different colors might have different shrinkage rate.
If the base of your model has too much bulk shrinkage, the print might drop even
with full XY size attachment layers. The attachment layers start getting lifted off
from the side (usually the longer side) that is closest to the model. This usually
happens on larger prints with more bulk shrinkage. In case the detachment
happens, please add supports at the bottom of your print. Bulk shrinkage bends
the supports a little so the attachment layers will be intact. The supports are
acting like a buffer to isolate the shrinking force from the attachment layers.
WARNING: In case the print drops because of insufficient exposure or
shrinkage, please remove the failed print as soon as possible. If the failed print is left
on the resin container with subsequent exposures, the adhesion to Teflon film will
increase, and the failed part stick to the resin container. When removing the print,
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please use a thin plastic blade to open small gaps around the print. It is a must to
minimize the vertical pulling force; otherwise It is possible that you will pull the Teflon
film off. Even if the Teflon film is not pulled out, the film may get warped locally.
Please take your time to remove the print softly around the print. Do not apply too
much vertical force in the middle.
8. Post-Printing
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Remove the build platform without touching the big knob of the ball head (on the
side).
Tilt the build platform above the resin container to let the excess resin drip back
into the resin container.
Remove the resin container without contacting the top steel plate in order to
avoid any potential scratches.
While holding the build platform, soak the model in an IPA bath (container) for
one to two minutes. If you have fine dangling structures, do not shake the model.
When removing the resin container or build platform after printing, please cover
the venting holes on top of the printer to avoid dripping resin on the projector by
accident.
Allow the excess IPA to drip back to the IPA bath (container).
For smaller models, use the blade provided to remove the model from the
platform. For larger models, use the blade to detach a corner of the attachment
layer and then use the spatula provided to separate the whole model from the
platform.
Allow time for the model to dry.
Post-cure the model with the build platform to reduce the shrinkage impact. If the
model is curing under the sun, you will need to rotate the model freuqently. If you
are using our UV lamp, the curing process will be faster than sun curing and
rotating the model frequently will not be required.
The post-curing process only dries up the surface of the printed model and the
time required depends on the type of resin and the wall thickness of the model. It
will take a much longer time for a solid model in comparison to a hollow model to
be fully cured. Curing will continue for a long time following the initial curing
process.
Recycle the used resin with a funnel. You many need a fine strainer or filter to
remove any debris. Solid debris could damage the Teflon film during the next
print. Therefore, ensure that at least half of the resin used for printing is fresh,
otherwise calibrated printing parameters may not work.
Clean up the resin container with dish detergent each time after printing. Do not
rub the film at the bottom of the container with excess force and do not use
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abrasive cleaning supplies, which may damage the protective film. If needed,
use IPA to gently wipe the container.
Warning! Do not soak the resin container with IPA. The container could be
damaged. Don’t rub edges of the Teflon film and the four corners of the PSP
resin container. Don’t use paper towel, which will scratch the Teflon film easily.
Please use a lens cloth.
After cleaning the container, if there are a little grease-like spots in the film, it is
okay. To dry, please use another lens cloth. To further clean, use IPA with a lens
cloth.
Please make sure to dry the container with soft tissue or a lens cloth.
Warning! Depending on the type of resin you use, the lifetime of the container
could drop if you leave the resin in the container. Please remove the resin
immediately after printing.
If you wish to print with the same resin immediately after another print, there is no
need to clean the resin container right away. Prior to the next print, make sure
there is no debris that may have dropped in the resin during the last print. If there
is cured debris in the resin, the Teflon film could be damaged when the platform
touches the container. Place the platform back to its original location and lower it
gradually to Z-POS = 0. Load the model and print.
Use a tea strainer (not provided) on top of the funnel to filter out the debris in the
recycled resin. Make sure to remove debris before recycling.
If you are mixing recycled resin with fresh resin, we recommend filling at least
half of the bottle with fresh resin. Please use a bottle that blocks UV rays and is
chemically resistant.
When recycling resin, try to take turns using the 4 corners of the container to
pour the excess resin. This will help to extend the lifetime of the container. In
addition, make sure to clean the outside of the corner after pouring.
When the printer is not being used, please cover the venting area on top of
the printer to block dust.
We recommend keeping the protective film of the projector case. In case you
remove them, it is a good practice to cover the projector with PE, PP or PET
film.
Please do not clean your acrylic cover with alcohol since the cover might get
frosted.
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