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

Plastic Shredding

First the material has to be shredded. We use ours QiTech Shredderbut if you don't have access to a shredder, you can also check the Precious Plastic map for workshops in your area, buy a new or used shredder at marketplaces like the Precious Plastic Bazaar or try some inexpensive methods, e.g. a manual shredder, a paper shredder or the scissor-blender combo. The more uniform the granules are, the better the end result will be.

Drying granulate

The next step is to dry the material.
We have already published detailed instructions on how to dry granules professionally or the cheaper (but less efficient) alternative with a homemade drybox.

Extrude

Next comes the main step: extrusion. For this, of course, you need a Extruder. You can build one yourself according to Precious Plastic's construction plans or buy one online, for example at Precious Plastic Bazar or our shop.
We also have a comparison list of different extruder models on our website.
Our Extruder is in its 6th generation and we have learned during the development that the following 3 things are especially important:
1. A suitable screw feeder
2. Accurate temperature measurements and controls
3. Easily replaceable nozzles

Cooling extruded filament

When the hot filament comes out of the Extruder , it must be cooled and wound onto a spool . You can cool the filament with water or air. We recommend using an air cooling system, as water cooling is a rather cumbersome, bulky affair. As long as you produce less than 3 kg/h, an air cooling system is perfectly adequate. The simplest and cheapest method is to use a tower fan positioned horizontally under the filament. We use our own cooling device, the QiTech Airpath .
Its fans can be precisely controlled to harden the filament but leave it soft enough so that it can be easily wound onto spools. The winding process works best when the individual filament sheets adhere easily to each other.

Filament Winding

Finally, the filament can be wound onto a spool so that it can later be used with a 3D printer. You will need a filament winder for this, which should have a tension unit, a guide (to wind the individual lengths from one side to the other) and a rotating winding axis. An important factor that you should pay attention to when buying/building a winder is that the filament always remains under tension so that you don't end up with loose spools.

We use our QiTech Winder for this step.
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It automatically adjusts the speed of the spool motor and enables perfect winding while maintaining the diameter of the filament. The filament is simply inserted into the puller, threaded through the guide and then attached to the spool .

Printing

Now the new filament can be used with a printer. Have fun printing!

PS: We now also offer the recycled filament for ordering!