Resin printers are devices that use photosensitive resins to create three-dimensional objects.
Unlike FDM (Fused Deposition Modeling) printers, which melt and extrude plastic filament, resin printers solidify layers of liquid resin using ultraviolet (UV) light.
Resin printers have gained great popularity in recent years, especially in applications requiring a high level of detail and precision.
This process allows for a level of detail and precision that is hard to match with other technologies.
Types of Resin Printers
Within the family of resin printers, there are different technologies. Some of them are:
SLA printers use a UV laser to cure the resin layer by layer. They are known for their high precision and are ideal for applications requiring extreme detail.
DLP printers use an LED screen or a projector to cure entire layers at once.
They are faster than SLA printers for small parts, but may have slightly lower resolution due to the pixelated nature of the projected light.
A modern variant of DLP, MSLA printers use an LCD screen as a mask to control UV light.
They are more affordable than DLP printers and offer a good balance between speed and quality.
Comparison with FDM Printers
Comparing resin printers to filament printers, we find that both technologies have their advantages and disadvantages.
High Level of Detail: Resin printers are capable of reproducing extremely fine details (making them ideal for miniatures, jewelry, dental prototypes).
Smooth Surfaces: Unlike FDM printers, which leave visible layer lines, resin printers produce smooth and uniform surfaces.
Speed for Small Parts: For small and detailed parts, resin printers are usually faster than FDM printers, as they can solidify entire layers in seconds.
Resin Handling: Liquid resins are toxic and can cause skin irritation. It is necessary to use gloves and eye protection when handling them.
Laborious Post-Processing: Washing and curing the parts requires additional time and materials, such as isopropyl alcohol and a UV curing box.
Limited Size: Resin printers typically have smaller print areas than FDM printers.
Material Cost: Resins are more expensive than the filaments used in FDM printers.
Here’s a summary table for you:
| Characteristic | Resin Printers | FDM Printers |
|---|---|---|
| Detail | Extremely high | Moderate |
| Surface | Smooth and uniform | Visible layer lines |
| Speed | Fast for small parts | Slower |
| Material Cost | High | Low |
| Post-Processing | Laborious | Minimal |
| Print Size | Limited | Larger |
| Part Strength | Low | High |
How Does a Resin Printer Work?
The resin printing process follows these general steps:
3D Model Preparation: Just like with FDM printers, you need a 3D model in STL format.
This file is loaded into a slicing software (slicer) specific for resin printers, such as Chitubox or Lychee Slicer. 
Slicing into Layers: The software divides the model into very thin layers (typically between 0.025 mm and 0.1 mm thick) and generates a file that the printer can interpret.
Printing Process:
- In SLA printers, a UV laser projects the shape of each layer onto the surface of the resin, solidifying it selectively.
- In DLP printers, an LED screen or projector emits UV light to solidify the entire layer at once.
- After each layer, the build plate lifts slightly (or lowers, depending on the printer design) to allow the next layer to be cured.
Cleaning: Once printing is finished, the part must be washed in isopropyl alcohol (or water, if it’s water-washable) to remove uncured resin. Then, it is fully cured under UV light to achieve its maximum strength.
Post-Processing: Finally, you have to cure the part under a UV light. The sun (intense, midday sun) can work, but normally you’ll have a UV light.
Also, the part needs to be rotated so the light hits it from all sides.
The “horrible part” is the cleaning and post-processing.
Where to Start with Resin Printers?
If you’re interested in exploring this technology, the normal thing is to start with a mid-range printer, like the Anycubic Photon or the Elegoo Mars, which offer a good balance between price and performance (they don’t pay me to say that 😅).
You will also need a curing chamber (absolutely necessary). They sell some cheap UV boxes for around 40-50€. Maybe that’s enough to get you started.
On the other hand, I highly advise you to buy water-washable resins. The biggest hassle with resin printers is managing the resin. If you remove the isopropyl alcohol from the equation, you’ll make your life much easier.
That’s about it. Be careful, use gloves, get a bit of practice, and soon you’ll be creating parts and Warhammer miniatures that will impress your friends with their level of detail.
