5 ways to bond 3d printed objects

To bond 3d printed objects together is necessary when you print a large object. All 3d printers’ capacity is limited. When you print a large object that exceed your 3d printer’s platform, you will often need to split the model into separated objects and join or assemble them together after printing. In this article, we will talk about the ways to assemble or bond 3d printed objects.

1.Bond 3d printed objects with glue

The most popular method to join 3d printed parts is to glue them together using adhesive.

Before gluing, it is best to roughen up the surface which will be glued with sandpaper. In this way, it will be stronger after gluing.

For most types 3d printing materials, such as PLA, ABS, PETG, you can use superglue to join the 3d printed objects. For some flexible filaments, such as TPE, Nylon and TPU, superglue may not work well.  So you should choose proper glue for your 3d printing material.

Because glue will make the objects stuck together permanently and it is hard to remove the glue, you need to be very careful in aligning the 3d printed objects correctly. In order to do that, it is best to design some locating structure when splitting the 3d model.

2. Bond 3d printed objects by welding

Welding is a process to joins materials. Usually you can melt metals or thermoplastics using high heat and allow them to cool causing fusion. There are many welding machines on market. We won’t talk about industrial welding machines here. We will only discuss some methods we can do at home.

2.1 Friction Welding

Friction welding is a process which generates heat by mechanical friction between parts. It is used with metal and thermoplastics, such as ABS and PLA. As a hobbyist, we can do that with a rotary tool to bond 3d printed objects.

You need to use a rotary tool to hold the filament. Then you can increase the rotate speed and apply light pressure on the parts’ surface (Part A and Part B in the following image). In this process, the parts and filament all are heated. Before the process, it is best to clamp the parts with some fixtures.

2.2 Join 3d printed objects with 3D Pen

3d pen is a tool to join parts together too. Different from friction welding, the filament is heated or melt inside the 3d pen, and usually the parts won’t be heated.

2.3 Hot gas welding/Hot air welding

It is a heat welding technique to join plastic. We use a heat gun to produce a jet of hot air, and the hot air then softens the parts and filament (or some other plastic filler rod). These materials will be bond together.

You can watch some videos to get more information on YouTube.

2.4 Solvent welding

Solvent welding is a chemical melting. We can apply some compatible solvent at the joint interface using a natural brush. And press the parts. The solvent diffuses into the polymer, softening the surfaces and allowing interdiffusion of polymer chains in the interface area. And that will weld the parts together.

For ABS, we can use acetone to apply solvent welding; some PLA can solvent weld with acetone too. HIPS can be dissolved in limonene.

3.Bond 3d printed objects by snap-fit joint

The most common structure is cantilever snap fit joint. When we insert the protrusion (hook in the following image) into a slot or cut-out, the protrusion deflects upon insertion. Once the protrusion is fully inserted, it bends back and lock the two parts. Not all of 3d printing materials are suited for snap-fit connections. Usually we recommend ABS, Nylon, TPU, durable SLA resin, PP materials.

4.Bond 3d printed objects by 3d printed threads

Every thread is a continuous helical groove of a specific cross-section generated on the interior or exterior of a cylindrical surface. Threads are not only used for screws; they also exist on linear drives, worm gears, pipes and many other devices.

For some parts, such as big parts, we can design actual threads directly as a feature of the part. After we print the parts, we can assemble them together by the threads.

5.Bond 3d printed objects by fasteners

It is an idea to design threads on the 3d models and print them on big objects. But for small parts, there may be issues to print threads. Of course, we can use self-tapping screws on small parts. But usually these screws are not strong and are destroyed easily.Another common resolution method is to use fasteners on our 3d printed objects, such as rivet, metal inserts, bolts, nuts, etc. These fasteners are used to assemble mechanical parts in traditional manufacturing every day.  These parts are very cheap and you can get them in a mechanical parts store.

How do you bond your 3d prints together? Do you have some other methods?

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