So you’ve heard about resin printing and it piqued your interest? In that case, you’re in the right place!
Also known as stereolithography (or SLA), this 3D printing method is becoming more and more accessible to hobbyists. Most 3D printing beginners start with FDM (Fused Deposition Modeling) printers that use melted thermoplastics to create an object. Resin printers work differently, besides using resins instead of plastics.
Resin printers deposit the material one layer at a time, just like FDM machines do, but they use a liquid photopolymer that is hardened using a UV light source. Essentially, the resin is cured either by a laser or a digital projector. This methodology enables us to create higher quality pieces with a great amount of detail. This factor alone should get you hooked on resin 3D printing.
How does it work?
As mentioned, these printers use a laser to cure liquid resin, thus creating a highly detailed shape. But there’s more to it than that.
The most common resin-based printers consist of several components:
- The resin vat.
- The build plate.
- The UV laser.
- Two galvanometers, which are needed to accurately point the laser beam.
Usually, the object is printed from bottom to top, but some printers will start from the top instead. The two models work a little differently.
The bottom-up printers will lower the build plate in the resin until there’s a thin layer of resin left between it and the film at the bottom of the container. Next, the laser is aimed towards the opposite side of the film where it starts curing the resin. Then the plate is raised, the cured section of the film is removed, and the plate is lowered back in its place. The 3D printer performs this process hundreds of times until the final object emerges.
On the other hand, the top-bottom machines will raise the build plate from the vat until there’s just a fine layer of resin on top of it. The laser is then aimed towards that layer, thus curing the resin in a set pattern. Next, the plate is incrementally lowered in the vat and new layers are printed until the object is finished.
With that in mind, top-bottom machines are usually designed for industrial purposes. The consumer-grade printers are bottom-top configured.
Should you get a resin printer?
The short answer is “yes”, especially if the budget allows it.
Resin printers are faster than the conventional thermoplastic filament printers and they can achieve much higher resolutions. For a hobbyist, resin printing is the ideal choice when printing small objects, like tabletop game miniatures (think Warhammer and D&D) or highly detailed action figures.
But resin printing is also used professionally to create vivid prototypes. With the right resin, we can even print functional prototypes. SLA is often used in dentistry and in the medical field, either to create accurate visual interpretations of a procedure or components for dental retainers and prosthetics. Resin 3D prints are a cheap solution and they are produced much faster than using the old conventional means. As a bonus, most resins are highly resilient to chemical agents and therefore they can be easily sterilized.
Types of Resins
While there are many materials available nowadays, all we need is liquid photopolymer (resin). It’s easy to get lost when researching all the available products, but for starters, we just want resin that can be cured when it’s hit by the UV laser (generally 405nm).
Once you get accustomed to working with resin, you can start exploring the wide variety of materials that come with all sorts of chemical properties and characteristics. In some ways, choosing the resin is like choosing the filament. If you’re printing something for medical use you’ll want a tough resin; if you want your miniature to glow in the dark, then buy a resin that has that property. The potential is unlimited.
However, make sure to look at the price tag. There are plenty of special industrial resins out there that will work even with a hobby-grade printer. Since most printers use a 405nm wavelength laser, resins are designed to be cured at that same wavelength. But you probably don’t want to spend $300 on a bottle of industrial-grade resin that has properties you don’t even need.
Another important aspect to pay attention to is the resin’s printing parameters. While most resins can be cured with the same laser, the curing time will differ based on the chemical composition of the material. Some resins will cure faster, some will require a certain ambient temperature for optimal use, and others heavily depend on the printer’s settings.
Speaking of settings, not every printer’s settings can be manually customized depending on the resin’s parameters. Some will come with several presets and you’ll need to buy the material that matches the parameters of the preset. With that in mind, let’s see how we can set up a resin 3D print.
The Step-by-Step Printing Process
Assuming you’re interested in acquiring a resin 3D printer, or you already have one, here’s a basic step-by-step process of printing a simple object.
Preparation and Orientation
Start by importing the model in the slicer. As a beginner you should stick to the software that comes with the printer, otherwise, you may encounter some complications down the road. In any case, the model has to be exported to the format which the printer understands. Once the model is loaded into the slicer, the next step is to choose the orientation of the print.
To pick the best orientation, you need to pay attention to the area that’s richest in details, consider where you’ll need to use supports, and avoid steep overhangs. Most resin printing enthusiasts will lift the print off the base. If you've been using FDM printers until now, you might be tempted to place the largest flat section on the bed. Don’t do that with resin printers. Try to set the orientation of the print in such a way that you can visualize the cross-section. By doing so, you will increase your success rate because there’s less peel force stressing the print.
Now that the print is oriented the best way, we can use supports. In most cases, they’re automatically generated, but you should consider manually inserting a few. Optionally you can design custom ones.
The purpose of the supports is to make sure that none of the print sections will overhang or peel away from the film during the printing process. Besides, good supports will provide better adhesion to all parts of the object and therefore we’ll end up with a successful print.
Using Less Resin (optional)
Resin printers allow us to print hollow designs. So before you start, you need to decide whether you want to print a solid object or not. Sometimes there’s no reason to have a solid piece, so why waste resin when we can drain it?
We can use a program, such as Meshmixer for example, and design a hollow print. Now, this will result in a lighter, more inexpensive object. But that also means we’ll end up with a weaker object. So consider this aspect carefully.
All we need to do is add draining holes to the design. The resin will quickly solidify on the outside, but some of it will remain liquid on the inside. By adding the holes, the liquid resin will flow out of our print. Just make sure you also consider the supports when changing from a solid design to a hollow one.
My Print Failed. Why?
Sometimes we end up with unsuccessful prints. That can happen for several reasons:
- The resin was too cold: The resin needs to stay warm otherwise it won’t perform optimally. So make sure to maintain the specified ambient temperature. Alternatively, there are ways to heat the resin vat. Printing at warm temperatures will increase your chances of success significantly and it will prevent other issues from occurring.
- There wasn’t enough support: Without enough structural supports, the print can snap in places or detach itself. We can fix that problem by adding more supports or by adjusting the orientation.
- Lacking adhesion: Base adhesion is important and if your print ends up warping itself or becoming detached, you probably don’t have a good enough adhesion. To fix that, you can make adjustments to the leveling of the bed, add more supports, preheat the base before firing up the printing process, or adjust the curing time of the base layers
- Bad resin settings: As a beginner, you might have trouble finding the optimal settings for the material you’re using. Make sure you follow the manufacturer’s recommendations and run a few tests before printing the final result.
Resin 3D printing is certainly different from printing with thermoplastic filament, so spend some time familiarizing yourself with the process. Once you get the hang of it, you’ll see that all those high-resolution pieces were more than worth the trouble.