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).

No slipping, no grinding: not always a good thing!

Let your filament slip, your bowden tube pop up... or break something !

If the filament cannot slip nor be ground a bit,
excessive pressure has to "break" something anyway.

Now for sure, and I can prove it: my driving system is very efficient and my bowden stays well clamped...

When I tighten the idler completely to the maximum, the driving bolt grips the filament so well that the weakest point in the feeder mechanism becomes the PTFE bowden tube resistance itself.

As you can see on the pictures, my PTFE bowden tube got stretched and stripped in the pneumatic push-fit connector!

This seriously clogs the nozzle and it becomes a real drawback in the end: check my analysis below.

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.

Robust bowden attachment with a blind rivet nut

Using a blind rivet nut to fix the bowden tube once for all

Blind rivets nuts give you a nut where you cannot reach the other side of the support.

How to clean the hotend and nozzle from the outside

How to remove clogged/molten filament in a V2 head?

Obviously you can disassemble the end, which is quite painful. It may also damage some items and threads in the long term.

Or you try whatever comes under you hand to remove the damn molten stuff in and around the PEEK. Of course, start by removing your bowden tube from the top quick coupling.

Replace the bowden tube

Replace the Teflon / PTFE / bowden tube

I ordered more Teflon tubing before running out of the original two pieces I received with the printer.

They had to be shortened regularly because they were getting damaged by traction in the quick connectors, and instead of popping out, some even was torn apart in the filament feeder plug !

The replacement I bought was a "teflon tube 4mm inner 6mm" (well, there is only one way to read the diameters). I got 12 ft for $19 with shipping on eBay.

Bevel the bowden tube ends

I use a very convenient tool to deburr/countersink/bevel the bowden tube ends. I found it by chance and it is very cheap. Now I use it everywhere (it also will deal with aluminium by the way).

There are two reasons to use it on bowden tube ends in my opinion :

• it reduces friction of the filament on the tube square edges
• it makes the tube softer so that it can be applied with progressive force against the PEEK for example, for a better seal

Before buying the tool I used my biggest drills, but it was much harder to do a proper job.

Filament plug, hot head and the short bowden tube

Get rid of a plastic plug in an early Ultimaker V2-like hot end

Updated: check my alternate blind rivet nut setup, it is way more robust.

Shortly after I changed the small bowden tube between the two plates of my V2-like hot end, I made the mistake to cut it a bit too short. Well, I did not try to find a place that would specify this the length, given that my head was not designed by Ultimaker in the first place -- I think.

Re-drilled the top brass quick connector

My hot end has a quick bowden connector made of brass and directly screwed in the top plate plywood (huh).

I recently had my second filament failure, located between the top and bottom plates. Two failures in 6 months still are too often for me, especially with this metric screw in the plywood (a metallic nut really should be insertedthere)...

I found some way to improve a bit though. I drilled the brass quick connector round and a bit wider. It had a hexagonal inner shape which aperture was uselessly smaller than the inner section of the bowden tube.