Filament End Retainer

The loose end of a spool of filament needs to be held to prevent the filament from unwinding. Most spools provide a series of holes on the wall of the spool through which the loose end of the filament can be ed to secure it. However, this often means that the filament is bent in the process, so when you next use the filament you need to cut 5-10 cm off the end of the filament to avoid issues with feeding the filament into your 3D printer.

Lately, a lot of filament suppliers have been providing little retainers to hold the loose end of the filament but I find the ones they supply and the one that are available from the community to be fiddly to use with the occasional mishap leading to amess of unspooled filament.

This small retainer uses less than 1g of filament and effectively secures the loose end. It is easy to use and holds the filament end securely. The retainer has two threaded holes, one with a slightly larger inner diameter than the other. To use it you the retainer over the filament through the larger of the two holes (the loosest fitting hole), threading sufficient filament through this first hole to bring the retainer back around to the open end, then thread the open end through the second tighter fitting hole. Then simple pull the retainer and the open end of the filament to cinch the knurled base of the retainer hard against the rest of the filament on the roll.

This retainer relies to some extent on the filament being held in each hole by a little friction. Since the size of the hole will vary a little depending on your printer settings, I provide a set of 5 versions of the retainer with hole sizes increasing from the #1 retainer to the #5 retainer. The #3 retainer works best for my printer and most of my filaments, but you should print this test set to identify the size that works best for you. The size difference between the inner diameters of the holes of each sequentially number retainer is 0.05mm (so around 2.5%) and the size difference between the inner diameter of the small hole and the large hole is also 0.05mm. You could make small scaling adjustment to the retainer to finesse the fit, though this should not be necessary. Both holes should be a friction fit for your filament with one hole slightly tighter than the other.

I print these with PETG with a layer height of 0.16mm, 98% infil and no s. The numbers are printed face down on the plate and I tend to use a relatively slow print speed.

I've included a .3mf file for AnycubicSlicerNext set up for my Anycubic Kobra S1 Combo for those with that machine, though you should be able to use any modern slicer to open the file to see the detailed print parameters and you may be able to open the file on your preferred slicer and change a few parameters to print the file directly from another 3D printer.