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
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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