FIGURE 68: Sample prints from a FormLabs printer. These objects were printed separately and then hand-assembled.
SOFTWARE: SLICERS FOR RESIN PRINTING
Because the printing process using SLA printers can be affected by many factors, many printer manu-
facturers have created their own software to manage the print process. Typically, that software is tuned
to print with a specific formulation of resin, and if you use third-party resin, you may run into issues. This
is especially true with all laser-based resin printers, because the software understands how to move the
laser in different directions to cure the layers calibrated to their resin.
Some proprietary software will allow you to tweak settings like exposure time or layer separation time,
allowing for other resins to be used, but some software slicers do not open those capabilities to you. As
mentioned before, check with the specific printer manufacturer you are researching to see how well it wel-
comes experimentation from its printer owners.
Conversely, having an all-in-one software system for resin printing can be a benefit. The FormLabs printers
use proprietary software called “PreForm” that functions as a slicer for their resin printers. This software
makes the preparation of models straightforward and does a great job at creating support structures for
the prints while offering convenient presets for FormLabs resins.
Slicers for other resin printers work a little more simply than having to create pathways for lasers to trace.
As you read earlier, these types of 3D printers shine a pattern on the build plate. Technically these patterns
are just a series of black and white images. For DLP printers, the white areas are the places where the
bright light is shining. For mSLA printers, the “white” color is where the LCD is disabled, and the black color
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is where the LCD is to turn opaque. In Figure 6-9 you see a typical set of layers that would be projected on
the build plate, one at a time, to form an object.
THERE ARE BOTH FREE AND PAID GOOD SLICING PROGRAMS FOR DLP AND MSLA PRINTERS, WHILE ALL
SLA PRINTERS COME WITH THEIR OWN SOFTWARE. A LIST OF POPULAR OPTIONS:
Lychee Slicer (free and paid): https://mango3d.io/lychee-slicer-3-for-sla-3d-printers/
Chitubox (free): https://www.chitubox.com/
Prusa slicer (free): https://www.prusa3d.com/prusaslicer/
(A note on PrusaSlicer...this software works with Prusa FDM printers, and the Prusa SL1, an mSLA
printer. Many people like the support structures created by PrusaSlicer and create the 3D models
in PrusaSlicer, and then export the 3D model (including support structures) then use one of the
options above to do the actual slicing)
Slic3r (free): https://slic3r.org/
FIGURE 69: A succession of layers that would be projected, one by one, on the build plate to create a 3D object
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is where the LCD is to turn opaque. In Figure 6-9 you see a typical set of layers that would be projected on
the build plate, one at a time, to form an object.
THERE ARE BOTH FREE AND PAID GOOD SLICING PROGRAMS FOR DLP AND MSLA PRINTERS, WHILE ALL
SLA PRINTERS COME WITH THEIR OWN SOFTWARE. A LIST OF POPULAR OPTIONS:
Lychee Slicer (free and paid): https://mango3d.io/lychee-slicer-3-for-sla-3d-printers/
Chitubox (free): https://www.chitubox.com/
Prusa slicer (free): https://www.prusa3d.com/prusaslicer/
(A note on PrusaSlicer...this software works with Prusa FDM printers, and the Prusa SL1, an mSLA
printer. Many people like the support structures created by PrusaSlicer and create the 3D models
in PrusaSlicer, and then export the 3D model (including support structures) then use one of the
options above to do the actual slicing)
Slic3r (free): https://slic3r.org/
Each one of these slicers takes the 3D model, adds supports to the model, for areas that need it, and then
outputs a machine-specific file that gets loaded into the printer. Sometimes these printers exist on the network,
but more often they get their printing orders from an SD-card that has the machine-specific file copied onto it.
Figure 6-10 shows a screenshot from Lychee Slicer with a nice little sitting chicken model on the build
plate. This model has been hollowed and has small lattice supports on the inside of the model to help with
FIGURE 610: A model in Lychee slicer with the cross section view turned on, hollowing enabled, and a 5% infill added.
FIGURE 69: A succession of layers that would be projected, one by one, on the build plate to create a 3D object
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structural rigidity. If you look closely, you can also see small grey drain holes have been added to each foot.
In the final print, these holes would also be printed, glued back into the model using some more resin which
is then cured, and then sanded to be seamlessly unnoticeable.
SUPPORT STRUCTURES FOR SLA PRINTING
Most SLA printers slowly pull an object, upside down, out of a vat of liquid resin. There are differences that
need to be taken into consideration for the creation of support structures using this technology versus FDM
technology.
THE THREE MAIN DIFFERENCES ARE:
The model is being printed upside down, so the effects of gravity on your model’s overhangs (com-
pared to FDM) will be reversed (Figure 6-11).
SLA printers can print much more accurately than FDM printers, and so the support structures
tend to be much more delicate and thin.
All SLA prints experience adhesion between the newly cured layer touching the bottom of the vat
and the build plate, or previously printed layers. In between actual printing, the printer will “rip
the print off of the bottom of the vat by moving upward, and then move downward again for the
next layer to be cured. Figure 6-11 shows the difference between SLA and PLA support structures,
including the first layer of supports seen in SLA prints.
Prints for resin printers want to reduce, as much as possible, the “cross section” of any given layer.
A thicker cross section rips off of the plate with more force, and can introduce print irregularities.
Printing many models at a 45 degree angle is often performed to reduce that cross section (but
this is very dependent on the model being printed).
You will want to hollow very thick models to both save on resin cost, as well as to reduce the cross
section of your printed model.
If a model has a large hollow area, and with thin walls, the “suction force” created by the build
plate “ripping” the newly cured layer off will stress those thin walls as that hollow grows. Think
of trying to drink a milkshake through a small straw...it is very difficult, and the walls of the straw
collapse inwards...the same thing happens with resin prints. Therefore, long/large hollows
usually have drain holes added near, and perpendicular to, the build plate to allow an “air gap” to
exist, eliminating suction pressure.
RESIN PRINTERS CONCLUSION
Resin printers require more discipline in order to get to a final print, but for many the process is worth it. Cer-
tainly, for those printing with castable resins in the jewelry industry, or who are printing gaming miniatures,
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FIGURE 611: Differences in support structures generated in Meshmixer with the same overhang settings for an FDM printer (left) and
SLA printer (right)
the benefits of a resin printer cannot be overstated. Due to the level of detail, SLA prints are immediately more
acceptable as finished products for most people.
You’ve now learned about FDM and SLA printers. The next chapter discusses the pros and cons of owning a
3D printer versus outsourcing the actual 3D printing to a service.
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