Back in 2023, we discontinued our original transparent plastic spools made from ABS that are not recyclable in NZ and introduced an extra-heavy cardboard spool with coated edge brim. As being the first one using such a-little-more-complicated cardboard spool, we were hoping to make a cardboard spool that is strong as plastic spool, that can be used in a multi-color filament box without issues.
In the past two years we have made quite few small improvements to the cardboard spool in each production batch. But there are two issues we cannot solve:
1. Random spools are off center a little much that swings left and right during rotation, which could get caught in multi-color boxes or filament dryers. We have requested the manufacturer to be more careful during production, but it will still happen due to the spools are glued together by 5 pieces of cardboard.
2. To hold the spool together without breaking during fast rotation, accidentally drops, and heated in dryer/oven at 80C for hours, we used excess glue to hold the pieces together. But doing so the excess glue always bleeds inside the center core where the pieces join, that sometimes also sticks the last coil of the filament onto the spool.
Since we cannot find a permanent solution for above issues, we have been looking for a plastic spool that is made by PET, HDPE or PP which are the only 3 plastics that can be recycled in NZ. Unfortunately, almost no supplier is making filament spools using these NZ-recyclable plastics due to the cost of raw material, and the injection mold of existing filament spools won't work on a different type of plastic as they will have different expansion/shrinkage rate.
Luckily, we have good relations with quite a few factories in China, one of them just happened to be a major plastic motorbike/car parts manufacturer, which can help us to make filament spools with any plastic we want. So, instead of spending money on paying the company who removed the famous "Don't be evil" motto from their code of conduct few years ago, to compete keyword search result with the seller who claim to be "Wondershop", we paid the manufacturer to make our own injection mold that is suitable to make filament spools using PP(Polypropylene, plastic recycling code 5).
The injection mold is a 60x50x43cm steel block made by Assab S136 steel, which goes onto a 380-ton injection machine. This is an over-kill for such small & simple purpose item, but the manufacturer only has big machines for large parts. The mold can be used one million times and by using a 380-ton machine it can produce one spool in every 65 seconds, that will help us to supply enough spools quickly to our filament manufacturer.
Cost wise, these PP spools(not including the cost of the injection mold) are more expensive than our cardboard spools, but we will not increase the price of our filament. We will continue to provide top quality filament while reducing plastic waste in NZ, as long as we can afford to.
Most of our filaments in the next shipment are made with our new PP spools. Although we have done quite a lot tests with the spool, being the first one using a PP filament spool, there will be small details we might miss. Please let us know if you run into issues with our filament spool, and we will see how we can improve them further. Thank you.
