Jun 24, 2015 | By Florian Horsch


This commentary is based on a couple of observations made during recent years in 3D printing. Let me start with a quick summary of my own path into our shared passion: In early 2011, I assembled my first 3D printer kit. It may sound cliché, but it truly felt like "First printer, first love"! I'm still using (and loving) my Ultimaker Original a lot.

Getting heavily addicted to 3D printing, I dedicated all my time to this fascinating technology. As part of my bachelor thesis I wrote a book about how to get into 3DP and through my own startup we co-developed the huge Delta Tower printers from Switzerland.

Lately with my own 3DP ambitions being hold (to finally finish my studies), I had some space to recap the last years and the progress the technology made since I had started. Within FDM/FFF there are not too many groundbreaking things going on anymore. Don't get me wrong! There are two or three new printers every week, while build volumes get bigger and a new filament appears on almost a daily basis. You get them stronger than ever before, in various flexible grades or sometimes cheaper and crazier. It almost seems like there's no limit to what's possible in material science. To me this is the beauty of FDM!

Can't Get My Head Around…

But the thing I can’t get my head around is: With all those standard plastics (PLA, ABS, HIPS, PET, PA, etc.) and the flood of new filaments… why the hell isn’t there more innovation going on in the hotend department? Of course we have the much beloved team from E3D with their version 6 hotends. Those little workhorses find a wider and wider adoption. Recently the experts from German RepRap decided to ship their new X350 with two of them!

So obviously it works for plenty of tinkerers, vendors and their end-users. But when using the whole bandwidth of available materials there are also plenty of situations were filament gets stuck, extrusion is not spot on or mechanical properties of the final print are subpar due to wrong print temperatures - you've all been there. On the other hand, we have new benchmark printers like the Zortrax M200 with impressive reliability. But that reliability is reached through the focus on just a few materials, therefore limiting the users choice.

Ahead of its times: More than two years ago Airtripper started a series of blog posts about a filament force sensor. © Mark Heywood

Mark Heywood, better known as Airtripper, made a first step into the right direction two years ago. With his Extruder Filament Force Sensor, he was able to sense forces via a load cell. Vincent Grampp and Patrick Creutzburg recently introduced a simpler setup. Their sparklab Feed-Sensor can’t sense exact forces, but detects when the filament starts to slip by comparing feed commands to the actual filament movement. The beauty of this add-on is a full integration into the more and more popular Repetier firmware, which enables all compatible 3D printers to be retrofitted.

Besides first steps on the sensor front, it all boils down to the question: Where is the truly smart, feature packed, but fully integrated hotend, which feels like a major improvement to everybody? Looking at the amount of problems discussed in forums and in the endless numbers of support tickets from major 3DP vendors, it's a question worth asking, right?

Looking for Solutions

Now we have a question. So we need an answer. Somebody with plenty of answers is the German inventor Kai Parthy. Within the 3D printing game there are few people who have continuously contributed towards the success of FDM/FFF like he did. In late 2012 everything started with one of his infamous videos, where he introduced the first printable wood filament: LAYWOO-D3. Since then, he added a dozen of even more futuristic materials to his portfolio.

Pulling a rabbit out of a hat: Like a magician Dipl.-Ing. Kai Parthy loves to showcase his latest innovations among a crowd of 3D printing users. © Dr. Stephan Weiß / Florian Horsch

When meeting Kai at one of the "usual events" he often brings samples of new materials with him. During EUROMOLD 2014, Kai approached me to tease about his latest work surrounding what he called "a revolutionary hotend concept". Regarding him as the incarnation of 3D printing innovation, I was all ears.

Back then he fobbed me off with a short list of planned features. No technical details, no drawings, just a summary of wonderful sounding highlights, such as "detects thermal properties of new filaments" and "adjusts printing profiles for every filament automatically". This sounded all too good to be true.

A picture is worth a thousand words: Kai Parthy's smart hotend vs. the de facto standard. © Kai Parthy

But at the 3DPrintShow Berlin, he was finally ready to share more details about the project of the "filament recognizing hotend". Besides evolving his ideas further, he already filed a patent for it (DE 102014017858-7, not published yet, exclusive preview at the bottom of this post). Giving Google Patent Search a quick spin impressively demonstrates that Kai isn't new to neither hotend innovation, nor filing patents. After learning the hard way that inventing something like LAYWOO-D3 doesn't mean that you are the one who is primarily profiting from it, that sounds like a legit approach to me. Given the fact that Kai is a one-man show, he is actively searching for partners from the industry to fully unlock the potential of his idea. Don't hesitate to reach out to him via kp@cc-products.de.

Has the Mothership Already Landed?

Before digging deeper into why we need a smart hotend, which automatically detects your filament and treats it in the best possible way, let me bring another patent application to your attention. US20150097307 was filed in late 2013 by the FDM-mothership Stratasys (published April 9th 2015). Looking briefly at the drawings, title and description, I wondered if Kai was too late, again. I fired a round of questions towards him: “Was Stratasys faster than you?” “Are you infringing their patent?” “Will this end the same way like your idea of a multi-filament hotend back in 2010 (another story in itself…)?”

Stratasys's patent application US 2015/0097307 A1 with annotations. © Stratasys

Kai took his time, annotated and compared. Indeed the two concepts seem to be quite different: While Stratasys often design their hotends for short-term usage (on some of their printers, users throw it away with every cartridge of filament used – the so called "QuickPack Print Engines"), Kai aims to build the ultimate hotend which not only treats a limited selection of materials properly, but also automatically senses new materials and their properties. By recognizing the way the material melts within the hotend, Kai's concept aims to create a print profile, which exactly determines optimal extrusion speed, temperature and retraction values.

Implications of a Truly Smart Hotend

Writing this sent shivers down my spine: So even my mom (or any other beginner in 3DP) would be able to print this fancy new material without any expert knowledge? One could even ignore the vague usage instructions from filament vendors, which normally fit for one printer and will cause frustration with others? No more trial and error for the fastest possible print speed when rushing to meet a deadline?

No! I don't want to think about this futuristic scenario! I want to continue to be an expert in FDM. I want to tweak my own settings, philosophize about optimal perimeter width to nozzle size ratios and feel really needed when others already gave up! No, Kai Parthy… your idea makes everything too easy!

Ok, fun aside: Holding my own airs and graces back a bit, I will continue to comment on both concepts and finally conclude in why I think that we need something like Kai's smart hotend.

Two Concepts – Side by Side

What's the concept of industry's heavy-weight Stratasys (based on the patent application linked above)?

1.) Specialized throwaway hotends instead of durable all-rounder hotends.
2.) Vertical cooling pipe (e.g. for coldness due to evaporation)
3.) Multiple stacked heating elements (heating resistor)
4.) Pressure detection within the filament channel through a sensor
5.) Optional: Square filament channel

What's the concept of Kai Parthy?

I summarized the white paper and drawings, which are attached to the end of the post.

1.) Printer recognizes the filament you're feeding into the hotend.
2.) Multiple heating zones are used to do so.
3.) But there are also two or even three cooling zones along the filament channel.
4.) Pressure within the channel is calculated by the back pressure of the filament.
5.) Calculates the best possible printing parameters and shares them with the community.
6.) By design deals perfectly with various amorphous, crystalline and filled materials.
7.) Creates autonomously optimal temperature curves for the most difficult to print materials.
8.) Even detects minor variations in material properties, e.g. between natural, black and white PLA.


The "not-so-smart" MakerBot Smart Extruder. © MakerBot Industries

Just because the current generation of hotends somehow works, we shouldn't hold back to take the next major step towards a much more reliable and versatile design. How crucial a properly working hotend and extruder mechanism really is became obvious when MakerBot introduced its 5th generation of printers:

The so-called "Smart Extruder" caused headache amongst users, leaving some of them so disappointed that they even started a change.org campaign to gather people for a potential class action lawsuit. From an outside perspective I would judge this flaw as one of the main reasons for MakerBot to lay off 20% of their staff. But it was definitely the reason for them to silently reintroduce the 4th generation models! From what I currently hear, the problems seem to be fixed by now. Interestingly this was done not through massive hardware changes, but with clever firmware tweaks.

Nevertheless it's still a good example of the importance of permanent mitigation of users' problems. For a company like MakerBot, it took surprisingly long to acknowledge and fix them. At the costs of business success and jobs…

Most hotend designs out there are working OK for a majority of users within a limited set of materials. In order to step up the reliability and usefulness of all those new materials, we need to start working on a truly smart hotend.

Personally I can't wait to see how the vendors and the RepRap community approach this topic. One thing for sure: It won't hurt to have Kai Parthy's expertise on board ;-)



1. Overview Kai Parthy's hotend patents (from 16.12.2012 ~ today)

2. White paper: filament recognizing hotend by Kai Parthy

3. Drawings of "filament recognizing hotend" by Kai Parthy



About the Author

Florian Horsch is an active long-time member of the 3D printing community. After early work on the Ultimaker platform he co-founded HypeCask.com. The Bayreuth-based team focused on customer-specific 3D printing projects as well as contributing to the development and distribution of the huge Delta Tower machines. In 2012 Florian shared his broad experience in the book "3D-Druck für alle" with a wide audience. Florian is currently poised for the exploration of new frontiers in 3D printing.

Twitter: @flouSH




Posted in 3D Printer Accessories



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jules rosen wrote at 6/25/2015 1:14:27 AM:

From smart type writers ( bal ) to inket to laser - back to inkjet multi head. And on and ON . My problem with 3d printing is that its still really in its infancy and you need some basic brains to get these to work . Really - simple idea is to INCLUDE the tape to place on the heated glass. Make extruders easier to open and clean . Add a chip or upc code to each roll of filament so the machine can read correct temp ,speed etc and set itself. Add tw osimple led and sensors t osee actual speed . Thats a big help for most of us ,,, Auto bed leveling is a must non -option folks . ( my 3d printer is a simple $ 600 solidoodle press. Regards to all - jules rosen

randy wrote at 6/25/2015 1:09:24 AM:

At the Geneva Invention Expo a company called 3DP showed a delta printer with a "smart cartridge" print head/hot end. I don't find much info about it now on the Internet: http://www.3dptechgroup.com/en/products.php but as far as I remember it did at least a few filament specific adaptations, sensed blocked print path, had a sensor to allow printing at maximum speed before too much vibration set in, some other stuff. Sorry I don't have more info.

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