Resin printers create 3D objects by curing liquid resin layer by layer. The print bed plunged into the resin tank, creating the object upside down. After each layer is cured, the print bed is raised strong so that the resin fills the space between the print and the FEP film, and the next layer begins to cure.
Almost all types of objects can be printed on a 3D resin printer. However, hollow objects should be avoided, as they can cause infections and tear the FEP filter (flexible membrane found at the bottom of the resin tank). To print hollow objects, the walls of the object must be thicker to be resistant (never below 1.5-2mm), and the object must have one or more holes to drain the liquid resin that may be inside.
Resin-based 3D printers have different safety concerns than filament-based 3D printers. Resin is a dangerous and toxic chemical, which must be handled with caution and care. There are people who are more and less sensitive to the resin (long exposure can create allergies due to the smell or contact with the skin). Symptoms of exposure to resin can be headaches, dizziness, difficulty breathing, muscle rash, among others.
For these reasons, it is advisable to always use proper PPE, such as latex or nitrile gloves, safety mask or respirators, and safety glasses. We also advise you to wear an apron, as the resin can stain and damage clothing permanently.
Cleaning containers (where isopropyl alcohol or water is placed to clean printed parts) must not be used for any other purpose than cleaning resin parts. The printer and these containers must be in a ventilated area, out of direct sunlight.
Resin 3D printers must be in a ventilated space without direct sunlight. Direct sunlight can cause unwanted curing of the resin inside the tank or on the parts being printed. The same care is required when cleaning objects.
Photopolymer resin is not food safe. However, impressions can be used to create silicone molds or other similar processes for developing food-safe parts.
It is a slicing program that determines the curing time of printed objects. This time will be different depending on the type of resin and its technical characteristics, but the exposure time can be adjusted. Sometimes the first parties can have a longer exposure time to guarantee adherence to the printing table.
A typical exposure lasts between 10 and 15 seconds per layer. The lower the object, the faster it will print.
We recommend angles between 15º and 20º, depending on the object – larger angles can cause objects to deform. Avoid flat surfaces running parallel to the FEP film, as angled surfaces are easier to print and support, preventing parts from breaking and falling into the tank during printing.
Yes, we recommend always using a raft. The raft creates a unified area, adhered to the printing table, creating more stability for the supports. It facilitates the removal of models from the printing table, without damaging the object.
Resin 3D printing printers are mostly simpler than FDM printers. They are plug-and-play and only move in the Z axis. As a rule, printing problems are derived from the slicer settings and not the machine. However, resin 3D printing requires much more laborious post-processing, as well as handling liquids and exposure to toxic fumes. It is necessary to take the necessary safety precautions at the printing site and post-processing.
There are several types of resin on the market. The one we sell is a Water Washable Resin, which simplifies post-processing, as it is possible to use potable water instead of isopropyl alcohol. But there are standard resins, plant-based resins that contain less chemicals, stronger resins similar to ABS, flexible resin, resin, wax resin for creating transparent molds, and so on.
When using a new resin, it is necessary to investigate the specifications of each one, such as curing time between layers and other necessary adjustments.
Any resin that comes into contact with the skin must be removed as quickly as possible. First, the excess must be removed with a paper towel or cloth, and then wash the area with soap. If the resin gets into your eyes, rinse with plenty of water and visit a doctor to rule out any serious injury.
First, it is necessary to shake the resin bottle for a few minutes. This step is necessary as the resin has a tendency to separate if left undisturbed for some time. Resin tanks have a line printed on the inside, which shows the maximum fill volume. Care must be taken not to let the resin fall out of the tank, as if it gets between the FEP and the LED screen, it could damage it and prevent future prints.
When you put the resin in the tank, it sometimes bubbles from being mixed. We must, with the plastic spatula, move the surface of the resin away from the bubbles until they disappear. If we proceed with these bubbles still on the resin, it could cause problems with adhesion to the printing table.
Yes, it is possible to fill the tank during printing, but we must take some care to do so. It is preferable to pause printing so that the resin can be mixed after addition. It may also be necessary to slightly heat the resin to be added, so as not to cause thermal shocks and possible defects in the print.
We have a video on how to replace the FEP film step by step, which you can watch here.
A print can fail in several ways: through the media; non-adherence to the printing table; parts that do not print; part shifting; between others.
We must remove the object from the printing table. Then check with the plastic spatula if there is any piece of cured resin stuck to the FEP film.
It is advised that the resin is filtered after each print, to prevent any cured pieces that are not attached to the print bed from remaining in the tank, contaminating the resin, and causing problems on the next print – damaging the FEP, the LED screen, between others.
When the object is attached to the FEP and not to the supports, it means that these were not strong enough to hold the object when it detaches from the FEP film. In this case, more supports, more contact depth, slower table elevation speed, or all of the above may be required. Even a thick support that has a small joint to the object may not be able to guarantee adherence to the object.
When we print in resin, the printing is done inside out. This means that the printing table will be moving up and down between layers to ensure the necessary liquid resin is present between the already made printing layer and the FEP film. Sometimes this sound happens because there is a suction force that holds the printed layer to the FEP, which when released causes the FEP film to hit the LED screen as if it were the membrane of a battery. We just have to be careful because if this suction force is too great, it can tear the FEP film.
These lines between layers are called layer offset, and it means that the new layer is not aligned with the previous one. Sometimes it can be a support problem, that is, they were not holding the object in the correct place with the necessary force. It can also happen because the printing table is not properly tightened/leveled, machine or surface movements during printing, incorrectly adding resin, among others.
Using the metal scraper, we must place it between the raft and the printing table to detach the object, being careful not to damage either the table or the printing.
After removing the object from the printing table, we must place it in a container with isopropyl alcohol or, in the case of resins washable in water, with water and a little washing up liquid. After a few minutes, the impression must be removed from the liquid and checked. If it’s a print with a lot of detail, you can use a soft brush dipped in the liquid to help get to all the corners. To check if it’s clean, you should let the object dry a little (with the help of a fan or kitchen towel). Well-cleaned resin will have an opaque/matte appearance, while poorly cleaned parts will be shiny. Repeat the process until the object is completely opaque.
Supports must always be removed before curing the printed object. It is advisable that the supports are removed with the help of needle nose pliers and tweezers. Thin supports on small prints can be easily removed with your fingers. It is necessary to remove the supports carefully, as incorrect removal can damage the printed object. We must clean the piece again in isopropyl alcohol/water after removing the supports, as resin residues may remain in the surrounding areas. Do not forget to use nitrile gloves during this process.
The curing of the objects must be controlled, and for that we suggest using UV light machines with a timer. If this is not possible, they can be cured in the sun, but with care to be exposed at different angles for a controlled time.
If the printed object is still sticky after curing, it means that it was not cleaned well and liquid resin residue clinging to the object was cured in the UV light.
A 3D resin print is made in layers, and sometimes we can see them on some surfaces, especially on round ones, or straight walls printed at 45º angles. The way to avoid or correct these lines is to lower the layer height, change the printing angle, or sand.
Unlike filaments, which are thermoplastics that melt at high temperatures, photopolymer resin does not melt/cure when exposed to heat, but heat can influence print strength and integrity.
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