How to make recycled filament from waste products such as failed 3D printing prototypes?

Plastic Shredding

First, the material needs to be shredded. We use our QiTech Shredder, but if you don’t have access to a shredder, you can also search the Precious Plastic map for workshops near you, buy a new or used shredder on marketplaces like the Precious Plastic Bazaar, or try some low-cost methods, such as a manual shredder, a paper shredder, or the scissors-and-blender combo. The more uniform the granules are, the smoother the material flow will be later in the Extruder —and the better the conditions for producing high-quality filament.

Drying granulate

The next step is to dry the material.
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Before extrusion, the granules should be clean, dry, and as free of other materials as possible. Especially with 3D printing scraps, you’ll quickly realize that “PLA” isn’t always just PLA—so it’s better to separate them properly beforehand rather than be surprised by poor-quality filament later on. We’ve already published detailed guides on professional granule drying and the more cost-effective (though less efficient) alternative using a homemade DryBox, which you can check out. We use the Digicolor Drywell here.

Extrude

Next comes the main step: extrusion. Of course, you’ll need a Extruder for this. You can build one yourself using the Precious Plastic blueprints or buy one online, for example at the Precious Plastic Bazaar.
We’ve been improving our Extruder over the years and, through this development process, have learned that the following three things are particularly important:
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1. A suitable feed screw
2. Precise temperature measurements and control
3. Easily replaceable nozzles

The more uniform the input material, the less the Extruder has to compensate. With our Extruder, features such as the temperature zones and the mass flow sensor help keep the process under control in case something does get jammed.

Cooling Extruded Filament

When the hot filament exits the Extruder , it must cool down in a controlled manner before it reaches the spool . For many setups, air cooling is sufficient—for example, using a tower fan or our QiTech Airpath for slightly higher speeds. If the cooling section isn’t sufficient at higher extrusion speeds, you can use multiple Airpaths in series. And for even more cooling power, the QiTech Aquapath offers water cooling—provided your material is compatible with water.

With the Airpath , you can adjust the fan speed to suit the material. The filament should become firm enough to be wound up, but not cool down so quickly that it no longer lays down cleanly on the spool .

Winding Filament

Finally, the filament can be wound onto a spool so that it can be used later with a 3D printer. For this step, we use our own QiTech Winder . It pulls the filament at a controlled rate and distributes it evenly across the spool via the puller, traverse, and spool shaft. To ensure that the filament isn’t wound loosely spool , it should always remain under tension during this process.

For actual diameter control, the Winder can also work in conjunction with the QiTech laser measurement system: If the laser detects deviations, the pull-off speed can be adjusted accordingly. This way, instead of five individual machines operating side by side, a single filament production line works as a unified system.

Printing

Now you can use the new filament with a printer. Have fun printing!

A quick note:

For your first experiments, you don’t need the latest technology or every machine in our complete filament line. However, if you process material on a regular basis, it’s worth coordinating the individual steps: Shredder(drying), Extruder(cooling), laser measurement, and Winder. The combination that works best for your material and volume depends on your specific application. If you have any questions or are interested in our machines, just drop us a line!