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).

3D printing with cheap Nylon trimmer line/string

Is filament quality so important after all?

I heard years ago that trimming line was one of the many materials that was tested on a 3D printer (the biggest list is probably here). This time I tried for myself, and it was also the proper occasion to deal with how "reliable" the material has to be (note that I wrote another post more specifically on how to print it).

Really, trimmer line may be a fully compatible filament !

My hot end is dying: the annoying PEEK thermal insulator started to melt (I suspect that the PID regulator overshot the temperature because of intermittent connection that I have fixed since). Still, it does not impede the flow much, so it gave me the opportunity to try some risky fun : what about this basic nylon trimmer line I got for free 10+ years ago when I purchased my gardening trimmer tool?

Rollerstruder: a filament feeder / driver / extruder

The rollerstruder filament drive system on an Ultimaker

Almost one year ago I got rid of the plywood Ultimaker filament drive mechanism. It is an extremely important part of the FDM process as it pushes the (cold) filament towards the (hot) end. Any malfunction at this stage systematically leads to a bad print. So when not reliable, you have to stay close and react quickly to fix troubles, for example by feeding the filament further manually (btw check this if you are still doing it on an Ultimaker).

As for me, most of the trouble came from the old bolt that was shipped with my printer: it was grinding my filaments a lot, sometimes to the point it would stop moving completely and ruin the hour-long printable kalashnikov. It also lacked Bertho's addition of a ball bearing on the "idler arm", which soon became part of the official design.

In fact I just don't know about the new official drive mechanism (which seems way more reliable given the forum feedback), because I designed my own feeder that has to match my more efficient but unsual hobbed bolt. It suits me completely: months of intensive usage without a failure. And I learnt a lot of openscad and industrial design by the way.

Which hobbed bolt for a filament feeder? My homemade one!

Driving the filament with hobbed / knurled bolts

My quite efficient hobbed bolt :)

As all owners of 3D printers know, one item of utmost importance is the so-called "hobbed bolt", "knurled bolt" or "driving shaft". It is one necessary "vitamin" (ie. non-printable) item that is coupled to a motor and which rotation drives the filament into the hot end (check the whole setup).

Now, molten plastic still does not flow easily through our tiny nozzles (~0.4 mm), and the force to be applied is quite high. Pushing the filament manually gives a good idea, as one hand is barely enough. Since necessary value may be 15 or 20 Kg of traction, this is where problems start to arise given the small filament diameters (3 mm or even 1.75 mm).

Printed filament feeder small gear

The small stock delrin gear on the feeder stepper motor got some freeplay with time. I first replaced it with one I found on thingiverse made by Chasmaker. You can download my derivative here.

Removable filament feeder : add a plug to the stepper motor cables

Add a plug to the extruder stepper motor cable !

The case slot design let me thought it would be easy to remove the filament feeder for transportation, good idea. But... did they forget that the stepper cables are going through the case with no way to unplug them ? Note that the unusual feeder itself is described here.

Lock the filament feeder in place

When I pushed the filament manually, I had to prevent the feeder from popping out of its attachment slots.

I designed this thing to make my life easier. Interestingly, it is also one quite popular object on thingiverse, so there must be a lot of people annoyed with this attachment (and because of failure with the hobbed bolt).

Actually I almost never had to push the filament manually anymore, but this is due to my new and own filament feeder design.

Replace the filament feeder big gear

I am not sure that the plywood I received was of top quality, because the wheel teeth started wear out pretty early.

Before it was too late, I designed and printed a drop in replacement. It is really working well, without any wear though I really made its life hard sometimes.

You may like also the small gear replacement.