Can You Melt Plastic Together?

So, you’re in the process of creating a 3D model, and you’ve realized that you need to join two pieces of plastic together. What do you do? 

One fairly obvious way of joining plastic in such an event is simply melting the plastic parts together. 

Can You Melt Plastic Together?

This method seems intuitive and logical. However, faced with a similar situation, you may find yourself wondering whether you should be melting plastic together in the first place and whether it will yield good results. 

Keep reading to find out whether melting plastic together is advisable, when you should (and shouldn’t) do it, and the answers to other frequently asked questions on melting plastic.

Can You Melt 3D Printed Plastic Together?

The short answer to this question is yes. 

The long answer is: in certain situations, melting pieces of 3D-printed plastic together is the best way to proceed with building a 3D model. This process is actually called welding. 

However, while there are situations where it’s absolutely fine to weld two pieces of plastic together, there are also times when it’s best to choose another method. 

We’re going to be exploring both sides of the coin, so to speak, in the following subsections, so stay tuned. 

When Should You Melt Plastic Together? 

There are a few different points in the 3D printing process where you may need to weld (‘melt’) plastic together. 

If your plastic has broken in the process of printing, welding it back together is probably the most seamless way of repairing the damage. 

Joints, especially joints with small surface areas, can also easily be secured together using the welding method. 

Certain shapes are also difficult to work with when it comes to applying glue. These include spherical shapes, curves, and other more intricate shapes that don’t take to glue very well. 

When Should You NOT Melt Plastic Together?

Certain types of plastic cannot be melted together, so you need to be sure of what kind of plastic you’re working with before you decide to do any welding. 

Thermosets are plastics that do not respond well to welding because they are unaffected by heat once they have initially been formed. 

Therefore, if you’re using thermoset plastic, you should not attempt to weld any two pieces together. 

You also should not try to melt plastic together if you don’t have the right tools or materials (listed below) since this could potentially be dangerous. 

What Tools and Materials Do You Need to Melt Plastic?

Can You Melt Plastic Together?

If you want to weld plastic properly, you’ll need a specific set of tools and materials. 

First of all, you will need a power drill. You could also use a Dremel or another kind of rotary tool that does the same job. Basically, you should use a speed-based or power-based rotary implement as your primary tool. 

You will also need something to hold the filament in place. A collet typically works best. If you’ve never seen or used a collet before, this is essentially a small version of a three-jaw chuck. 

Finally, you’ll need a piece of filament in the right color to act as the plastic ‘glue’ in the welding process. You’ll normally need a few inches, and the filament should protrude roughly 15 to 30 millimeters from the collet when you have cut it. 

You can purchase a power drill and a collet from your local hardware store, or you can find them through online retailers. This cordless drill from Black and Decker is a good choice, as are these common-size collets from Findmall

How Do You Melt Plastic Together?

Once you’ve gathered together all of the materials and tools you need, it’s time to get welding!

This process is easy to master but requires a lot of precision and focus, so read these instructions carefully before you get started. 

First, you’ll need to set up your working area. Once you’ve cleared a space, the first step is to prepare your filament. 

You’ll usually need a few inches of filament, although this varies depending on the area you need to weld. Place the filament in the collet and leave roughly 15 to 30 millimeters of filament protruding from the collet before you cut. 

A 45-degree angle is usually the easiest to work with, so make sure that the filament is positioned correctly at this stage. 

At this point, you should make sure that the filament is as straight as possible. Try to work out any curves or kinks using your fingers and apply a little heat (e.g. from a hairdryer) if needed.

Next, set your drill to a medium speed. You don’t want it to go either too fast or too slow since the former could get messy and the latter will waste time. 

When you have the drill at the right speed, touch it to the filament using light pressure. Now, either work from right to left with the filament perpendicular to the welding area, or make small circles with the drill as you follow the seam downward. 

If you feel that more plastic is needed in the seam after you’ve done this, wait until it has cooled down and do the same again to create another layer. 

Finally, if some lumps and bumps are left behind, sand these down with some sandpaper or conceal them with polish or paint. 

Final Thoughts 

Melting plastic together, also known as welding, takes practice, but it’s easy once you master the technique. 

All you need is a power drill or rotary tool, a collet, and a piece of corresponding filament to weld plastic. Sandpaper, paint, and polish may also come in useful. 

The key to melting plastic together is to practice the right-to-left or circular welding technique since these produce the best results. If the weld doesn’t look perfect straight away, don’t worry – it’s probably nothing another layer, some sandpaper, or a lick of paint won’t fix. 

Remember, welding will not work on thermoset plastics and you should never attempt to melt plastic together if you don’t have the right tools. 

Michael Moore
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