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Friday, March 10, 2017

Low friction filament spool holder made in 3 minutes

Here is a short post on yet another low-tech but functional tool (the last one was a dry box).

Give a maker a 3D printer and every problem is solved by 3D printing... A few years ago I started to re-realize that many problems are solved much better without 3D printing. At some time it was funny to see everything being 3D printable, including pipes, but how slow and inefficient it can be.

So here is a recent counter-example: I had to use a small, cheap but functional 3D printer recently (a sub $350 Me Creator Mini, a pretty good choice as an entry-level printer in my opinion). But it runs on 1.75mm filament and it lacked a compact, reliable low friction spool holder (the default is attached to the back of the printer, far from the side due to the electronics, and which is made of PVC pipe: the filament often jumps off the spool, which quickly fails).

I was both in a hurry and lazy, so I wanted a quick hassle-free solution.

First idea: go find a design and 3D print it?

It was a long time I did not go to Thingiverse. When I do I have an "infinity" notification count on my own designs! I checked the existing designs, and... there are right now exactly 3,927 designs which are tagged "spool holder". By the way, there is even a super funky marble-powered one.

No way I will review thousands of designs until I find a "proper one". I do not want to print three of them to get one working (with possible additional problems with the printer I have at hand... like the very filament entanglements I want to fix).

So, interestingly, no existing design suited me, my own spider spool holder included.

Second idea: no biggie, I design a new one and 3D print it?

Easy, with Openscad. But, doing so takes even more time! And that would make a 3,928th design on Thingiverse.

Adding further steps or functionality between the idea and the realization is one of the best way to end with nothing. When I start designing something, all kinds of questions jumps at me. No way here, I need my spool holder (remark: I write this months later of course, but the idea to write about it jumped at me when I was doing it...).

Final idea: make it crappy, and do not print it!

So here it is: a roller box that took me about 3 minutes to make. And it works very nicely with super low friction for the feeble filament driver of the printer (unlike my bulky one on the UM).

The box originally held an assortment of plastic anchors (large review here). It looks like most of the "Parts Organizer" boxes.. The small hole I drilled, and filled with a piece of low-friction bowden tube was not useful in the end, as the thin filament never slips away of the spool.

I used four super cheap V-grove roller bearings I bought on ebay years ago, with the intent to build a cheap fishing line-based CoreXY printer (see, e.g. this) -- which I obviously never did.

The groves were made with a grinder, faster and safer than with a cutter.

You can add little pieces of tubing to keep the roller bearings in place, like above and below. Without V-shaped bearings you probably can get cheaper even, by using glued stacks of washers, that you enclose within a pair of bigger washers: the deal is to forbid the spool to drift aside. Friction on stainless steel with not be significantly higher than with bearings.

Note that the small outlet is useless when the whole is on a table,
as it bends the filament too much. I have yet to see the filament
jump over the front pair of roller bearings.

And as a bonus: I eventually made use of those nice, sturdy, shiny metal arms that I always collect on used windscreen wipers :)

You get a short video here (same as above).

I now realize I spent much more time writing the post than making the stuff, so I hope you like it: all in all may be I could have 3D printed one... :D

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