Whenever you want to print larger than your 3D printer build space you are going to find yourself wanting to combine 3D printed parts together. Furthermore, as you wrap your head around 3D printing, you learn to save on filament by printing in ways that do not require as many supports but do require assembly after printing. One of the most common filaments used today is PLA so very often this is the material you will want to combine. So I tested to find the best glue to use.
The experiment was to compare the Strength of SCIGRIP Weld-On 16 VS Superglue when combining PLA components that have made from 3D printing.
My findings are that Superglue is the best method to combine 3D printed PLA components but both types of glue do produce strong connections between parts. Superglue is both faster to dry and produces, based on my destructive experiment, a stronger connection. This experiment on the best glues and the result did not result in any surprises but it did result in a 3D printed Ukulele which I am ecstatic over.
This guide will go through the experiment. This video and project page dives into the process of designing, 3D printing, constructing, and tuning a 3D printed Ukulele. If that takes your fancy a lot of tips for your own creations can be taken from the build process. The Polymaker PolyWood (PLA) filament used for the body of the instrument produces an excellent reverberation because of the density that matches that of wood. Below are the contents of this guide.
- Details on Glues Tested
- Process of Prepping and Gluing 3D Printed Parts
- Destructive Testing
- Results
An Ultimaker S5 and Ultimaker 3 3D Printer was used to create the components utilised in this experiment. Check out the guide Improving 3D Printed Models to learn excellent ways to do just this. It also got me wondering what else musical you can 3D print, one quick look online I found an Ocarina, a Fiddle, a Magic Death whistle, Bagpipe components and even a Trumpet. All with free files readily available to print.
As always if you've got any questions, queries or things you'd like to see added please let us know your thoughts!
Details on Glues Tested
Before diving too deep into this topic (it hopefully goes without saying) do not ingest these glues and try not to get them on your skin or eyes.
This experiment has come about as I had recently discovered a whole new world of Fast Set Solvent cement and had to try them out for myself. For 3D printing applications, SCIGRIP Weld-On 16 kept coming up as the best method for combining 3D Printed PLA components. So I just had to put it to the test. See below for specific details on the two types of glue.
SCIGRIP Weld-On 16
- Good for PLA and is also good for acrylic.
- It will chemically melt PLA (or acrylic) thus components become fused together.
- It will take a couple of days of drying to reach a high strength
- If it does go on your skin it is easy to wash off with water
Super Glue
- Brilliant glue for almost every maker project
- It is a resin which when it absorbs water hardens to full strength
- Very fast drying
- It turns into a rigid mesh when it hardens. That mesh grips together with the components
- If it goes on your skin you cannot wash it off with water.
Process of Prepping and Gluing 3D Printed Parts
Whenever combining 3D printed components always sand/scrape up the butting components. I use 360 grit sandpaper for this purpose. This will increase the surface area of the combined parts and this will improve the strength of the connection.
Make sure to cover the surface area of both butting components with glue and press both components together. When possible, utilising clamps will create better connections. Use a rag or paper towel to clear off any extra glue. For superglue, it will reach maximum strength within a couple of hours. For SCIGRIP Weld-On 16 it will reach maximum strength after a couple of days.
This was the same process I did for the Ukulele, however, I was unable to use a clamp to combine the components. Thus, I held them in place until the glue set enough to hold the components. Then I left the SCIGRIP connected parts to dry overnight.
Destructive Testing
The 3D printed PLA test pieces were glued together with both types of glue, secured with clamps, left for more than 3 days and then destructively tested so we can compare the strength results of Superglue to SCIGRIP Weld-On 16. The wall thickness of the test cubes are 10 layers, infill was 30% for these 20x20x20mm cubes and was printed using Ultimaker Tough PLA with a 0.4 mm nozzle at 1mm layer height. These pieces were printed on an Ultimaker S5. Super Glue was used on the cube marked with an X, SCIGRIP Weld-On 16 was used on the cube marked with O, see image below. All butting surfaces were sanded with 360 Grit Sandpaper. The glue was evenly coated over the butting surfaces. All parts were clamped together.
Destructive testing was first started with plyers, putting the cubes under tension, then a moment (bending the components apart) and finally a torque to the best of my ability. I was surprised that they passed this test. So Vice Grips were brought in. The cubes stayed connected under tension, then when the pieces were put under a moment they both gave way. This you can see in the images below for the SCIGRIP Weld-On 16.
The Superglue component required significantly more force to pull apart and tore at the glue section. The SCIGRIP Weld-On 16 component was easier to pull apart and tore along several layer lines. The layer lines under cross-section analysis appeared to have been melted together, as they should. This you can see in the image below.
Results
So even though the SCIGRIP Weld-On 16 does what the label states, melting the PLA components together, the winner in my experiment was the superglue. Possibly the process of chemically melting the PLA affects the strength of the PLA making it easier to tear.
Nevertheless, my advice is to combine your components together with superglue unless you want a connection that is completely PLA without any resin mesh in-between. I will boldly say that not having that resin mesh but instead a consistently PLA connected neck to body improves the acoustics of my 3D printed Uki. Hopefully, this has inspired you to feel limitless and get out there 3D printing objects that will become much larger than your print area.
