SLA printers usually have small build volumes. Suppose someone wants to print something big with them. Printing several pieces and then gluing them together is the best solution in this scenario.
In order to do that, It’s essential to use the best glue so that the print’s appearance is least affected.
Here, we will check the best options for gluing SLA prints so that the output becomes strong and precise.
What are the best glues for SLA resin?
Cyanoacrylate, resin plus UV light, epoxy, and silicone adhesive are the best options for gluing SLA prints. Cyanoacrylate is guaranteed to create a strong bond between parts while curing the resin itself has the most natural look. Epoxy and silicone adhesives are other options for gluing prints.
If you want to learn about each of these glues, and their pros and cons, and how to use them correctly, keep reading.
Superglue or cyanoacrylate, also known as “Crazy Glue,” is an adhesive that can create perfect bonds between different materials such as metal, wood, and cured resin.
In contrast with traditional water-based glues, cyanoacrylate is composed of acrylic resin. As the name states, the main ingredient in this glue is cyanoacrylate. These various features give superglue some unique behavior that makes it a suitable option for gluing cured resin.
Cyanoacrylate needs water molecules to cure and make a strong bond; the curing process doesn’t require lots of water, though. In most cases, a surface’s moisture is more than enough. Thus, if the weather isn’t harshly dry, you have nothing to worry about.
However, cleaning the bonding surface before using the glue is the best practice.
The curing of different superglue brands may vary. As mentioned, the glue needs slight moisture for most brands, and the curing process immediately occurs. The cured glue usually is strong and brittle.
Usually, the curing doesn’t require special conditions; but it’s recommended for some brands to use it at specific humidity or temperatures. Therefore, it’s wise that you check the product’s manual before using them.
The only main drawback of using superglue for SLA prints is its extreme brittleness. However, there are some flexible superglues available that completely solve this problem.
Cyanoacrylate glues come in different viscosity, so you can get a watery glue to reach better precision. But this way, there is a high chance of accidentally dropping some droplets on your skin or print.
The human’s skin usually has enough moisture for the glue to create a strong bond. In such situations, the best solution is to use acetone. It can quickly dissolve the glue and rip it apart from your skin. It would be best to wash your hands after using acetone.
If superglue leaves on your print, you can use a toothpick impregnated with acetone to eliminate it. Beware, though, that there is a possibility to dissolve some of the print’s surface with an excessive acetone amount. Thus, it’s best to add the least solvent.
The cyanoacrylate glue’s composition has a short lifetime. Superglue’s shelf life is around one year, while it decreases to one month after opening it. Therefore, buying this product in bulk for future usage isn’t a good idea.
In general, cyanoacrylate can create a strong bond between your printed pieces. It doesn’t create distinct bonding lines, and with some post-processing, it won’t affect the print quality. However, most superglues are somewhat brittle and can change the appearance of the output.
There are many superglue brands available in the market. Here, you can find some of the best ones with various features.
One of the most popular products in various fields is Gorilla Glue. It can create perfect bonds between printed pieces, no matter which resin or printer you use. The glue is watery enough to fill small cracks and create a nearly invisible line. The curing time of Gorilla glue is quite fast, so the bonding surfaces should quickly become aligned.
Gorilla glue is quite brittle. Depending on your project, this feature may be a problem. In such cases, less brittle super bonds like the Permabond’s flexible cyanoacrylate are the best alternatives.
At first, using the flexible word for cyanoacrylate may seem misleading though it’s true. Flexible CA can stretch up to four hundred percent elongation! Thus, this one won’t easily break or affect print quality.
This product can bond every substance that other superglues bond. However, the result is softer and, of course, flexible.
Permabond also has different products with various viscosities, so you can use watery glues to increase precision.
Another way to improve precision is to use “precision needles.” They come in a variety of gauges. Thus you can choose the right size for your prints. Precision needles are disposable and need a lure lock adaptor to connect to the glue’s bottle. This product is pretty cheap but can heavily improve your work.
The video below is an excellent example of precision needles in practice.
Superglue can create a perfect and permanent bond though the results won’t reach the quality of one-piece prints. They often have a different color than the original resin and need some practice to achieve acceptable results. Another way to bond the printed pieces is to use the same wax and UV light.
Resin plus UV light
As you know, SLA printers use a source of UV light to cure thin layers of resins on top of each other to create a solid object. In this process, the liquid resin adjacent to the cured resin can create a strong bond with the solid phase while it’s exposed to UV light.
What if we do the same process manually and use liquid resin and a UV source to create such bonds? This way, we can produce the most natural-looking outputs because the gluing material and printed parts are made of the same resin!
Cured resin can correctly hold printed pieces together though the produced layer isn’t as tenacious as the printer’s ones.
This method also works best for gluing surfaces with small surface areas. Because significant surface areas can prevent the UV light from curing the internal resin, only the perimeter resins solidify, and the bond becomes less robust.
Depending on the UV’s wavelength, this process may become quite dangerous. So remember to use protecting gloves and sunglasses while working with UV light.
In the video below, you can find the actual process of using resin and UV to bond printed pieces together.
Epoxy is a liquid substance formed from hardener and epoxy resin, which solidifies after a particular time. These two substances should be stored separately and mixed together upon usage.
You can use it to glue resin printed parts together, fill the bond layers, or fill empty spaces in your prints. Epoxy is entirely compatible with most post-processing types. You can also use it along other glues to create invisible bonding lines or save expensive adhesives.
Even though epoxy’s curing time may reach more than one hour for some products, others solidify within a few minutes. Five and twelve-minute epoxies are the two everyday products available in local markets.
During the curing time, you can move and adjust edges to reach the desired position. Note that epoxy needs more time (around a couple of hours) to reach its maximum adhesion. Thus, it’s best to give it this time to achieve excellent results.
Working with epoxy resin and hardener is relatively easy. In this video, You can learn the general process.
If you ended up with epoxy on the wrong surfaces, you could easily remove it with vinegar on a cloth. However, if the epoxy was tough, you can use acetone to loosen it. As always, be careful when you work with acetone, and keep the area ventilated.
You may have seen a plumber use silicone adhesive, or maybe you have used them yourself for DIY projects. In that case, you are familiar with this glue.
Silicon adhesive is a liquid substance that looks like gel; If you give it some time, it’ll create a permanent link between almost any two objects. Furthermore, silicon is resistant to moisture, weathering, and chemicals.
Gluing with the adhesive for SLA printed resins has some unique benefits. It’s flexible, semi-transparent, and easy to use. However, The bonded layer may look disharmonic and affect the print’s appearance.
There are several silicon sealant brands with various purposes available in the market. It’s necessary to use electric or high-temperature-resistant grade adhesives for related works, But for printed pieces, you can use any brand.
It’s also cheap; You can get a cylindrical container of silicone sealant and use it for hundreds of projects.
There are several options for gluing SLA resin, and each candidate has a unique feature that makes it an attractive choice.
You can use cyanoacrylate to reach a strong bond, Use resin and UV light to get the most natural result, or use epoxy to fill gaps correctly. Silicon adhesive is another glue that is more resistant to environmental factors.