Recycling in favor of building boomerangs is not a new topic for the blog, 
3 articles have already been published. It was time to take it up a notch.

By dint of making boomerangs, we see that the scraps associated 
with the cuts are numerous and that the plastics to be recycled 
are abundant. 
More generally, the problem of plastic waste which is struggling to 
be recycled is increasingly present in people's minds.

 

I was looking for a solution to re-use these scraps and why not other 
abandoned plastics to give them a second life.

The primary objective is not to make a 100% finished boomerang
 (with the profiles) but to be able to hand-mold boomerang blanks
 in original materials, not often used.

 

Through research, I discovered the Precious plastics initiative which allowed 
me to evolve in my approach. Instead of finding material slabs and carving 
boomerangs out of them like I had done previously, I was going to be able 
- thanks to the machines they offer - to melt scrap plastic into boomerangs.

The first step was to build the injection machine, the second to make a mold.


The objective is not to detail here all the stages of the construction 
of the injection machine, the video below does it very well. 
On the other hand, I explain how to simply 
make a mold (you still need a little tooling) and some preliminary 
results of my experiments.

The Precious Plastics website

Precious Plastic's tutorial for making the injection machine


This video explains in detail how to build a plastic injection machine, 
this realization requires an advanced level of DIY and a minimum 
of equipment.

It is necessary to file the irregularities to arrive at the final 
contours of the future injected boomerang. 
The surface finish of the edges will be reproduced on your molding. 
Fine sanding (180 grit) is recommended to have a nice finish appearance.

Upper part of the mold

These are the same steps as the lower element. 
Once this element is done, drill a hole in its center to weld the nipple that is 
screwed onto the injection machine.

Injection

 

Before molding, the plastic must be prepared for injection, i.e. cut
 it into small pieces (or better to reduce it to granules) 
so that it can enter the heated part of the injection machine, where it will melt.

At first, the injection may not be complete. 
Either you have not put in enough material, or the plastic is not melted
 enough / not hot enough, or the mold is too cold 
(this problem disappears after the second consecutive injection).

Remember to put a dust collection bin when sanding your blanks, to be able to recast them into boomerangs.

The flight test

Here is a test video of a speed made in Polypropylene TD20 
(Talc 20%) from recycled auto parts.

Wind conditions between 10 and 15km / h.

[This boomerang was used during the Moirans tournament 
on August 29 and 30, 2020 to take second place in FC and 
fourth in endurance (51 catches)]

Warning // Security.

Protect yourself, pay attention to your health, respect the 
safety instructions of the machines you use.

Wear a mask, goggles and gloves, the mold is hot after injection (over 100 degrees C)

Vacuum all plastic dust for recycling, do not throw your plastic waste in nature, 
put it in the recycling circuits provided for this purpose.

Watch out for vapors from hot plastics.