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 a smaller nozzle diameter

For sure, a smaller nozzle produces finer details,
but how tricky and troublesome it can be!

Is it worth using a smaller nozzle on a 3D printer?

I changed my hot end after my experiments with cheap nylon trimmer line, and it happened I had a 0.3 mm nozzle around. Was it worthwhile for even finer prints?


True, you can / do get finer details... but once again, there are trade-offs. And as for me, I will still mostly use a larger nozzle for the reasons I explain 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?

Copyrights and 3D printing: a forthcoming war bigger than that of the MP3 music

So, what about copyrights?

Free and customizable GoPro-compatible mounts:
not illegal because I designed them! Still, would GoPro
appreciate it when they would charge $30+ for this?

It is no secret by the early adopters that 3D printing at home will soon become one major copyright battle. And I sincerely hope the industry will find a better answer than that of the music majors regarding mp3 music, or they will just fail anyway.

Will all the printer owners become the next pirates? And reciprocally, will the big player violate our own creative commons copyrights (or impede innovation at the hobbyist level with they own broad patents, see my longer post on the subject)?

Is there a chance that we soon get commercial repositories where we can buy, download, customize, and print Lego bricks, Barbie dolls and cheap vehicle spare parts? Or will it be the hard way with inefficient injunctions, DMCA and court battles again ?

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.

What cannot be 3D printed? Time to debunk some myths!

General 3D printing misinformation: review of facts and fiction!

Each technology has some fundamental limitations, and 3D printing is no exception.

As soon as I owned and wrote about 3D printers, people started "spamming" me with mainstream articles about it (no pun: still I like them and still I learn from them!). So even our grandparents would soon be printing their glasses, their bikes, their firearms, their houses and even their own legs!

For sure, I am not the one that will disenchant this emerging technology: I am writing this blog and I regularly post new designs on Thingiverse repository.

But as I write this (april 2013), you just cannot buy a 3D printer and print anything, nor even expect it to work as advertised if you do not understand very clearly how the thing works. It is just not reliable enough for the average user (unless you have no special expectation, in which case this pay doh printer may avoid frustrating experiences). It is even quite hard to reach an acceptable quality even for people born with a screwdriver in their hand.
Update 2021 : we're closer to reliable, out-of-the-box 3D printers. Still they often need to be properly tuned, especially the low-cost ones. And time will not fix their other drawbacks. Please read on!

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).

How to run a (Cura) Python plugin on STL files without Cura?

Here is a geekier post about how to tweak Cura plugins and convert them to standalone Python scripts that post-process your g-code without Cura nor Skeinforge.

After I designed and used my wood gradient plugin, people naturally started to ask for the source code. I was a bit lazy first, because it was made for Cura 12.08: the patch I released was not very convenient, and Cura had evolved with a better and simpler plugin system, and included my own plugin.

Then, I got the time to fix it. Here is how I converted it to a standalone Python script that runs on its own, asking nothing to nobody.

Molding and casting with a 3D printer

Printing a mold and/or lost wax casting

Or how a 3D printer also opens the way to semi-industrial homemade objects beyond artistic sculptures!

Indeed, a 3D printer can be used indirectly, to print a mold of the object and not the object itself. The print is used as a "shape", and the final object is made of something else that could not be printed directly such as aluminum or silicone.

Molding is also useful to produce small batches of objects (even out of plastic), in a way which is much quicker than by 3D-printing. 3D printers are only rapid prototyping machines not ready for mass production.

Ron Thompson explains clearly how he made his aluminum heating block for his gravity filament extruder:
here is a two-part oil-bonded sand mold, rammed around the above 3D-printed orange plastic shapes.

How fine can an Ultimaker print?

 Ultimaker impressive quality at smallest layer heights (40,50,75 microns)

I printed one famous treefrog on my Ultimaker for a friend and realized I have forgotten so far to speak about the overall quality you can reach with this printer.

It gets hard to feel the layers by sliding your nail (75 microns layer height).
The most prominent place where layers show up is between the eyes.
This print is not postprocessed (see the hair-like filaments not yet removed/sanded/burnt)