My month as a special guest at E3D

My month as a special guest at E3D

It was January, I was home in snowy Sweden, everything as normal. A few of us were killing time, talking how to print big Benchys on Twitter, when E3D Online suddenly posted an image of some nozzles from their soon to launch Super-volcano HotEnd. Which promised to have 2-3x the flow of a standard Volcano, or up to 9x higher flow than a standard E3D V6.

A bag full of the biggest nozzles we had ever seen

A few messages later, I was invited to test them, and to stay at E3D HQ for a full month! Not only would this mean better extrusion rates for the Hangprinter Project; it also meant space to host the first Hangprinter Assembly Workshop, including access to tools, equipment, and input from the E3D engineers. And when I thought it couldn't get much better, Richrap joined in as a workshop co-instructor.  As May came closer, plans just kept getting better. In the end, a handful of friends and RepRap heroes came and celebrated RepRap's 10th birthday with us, right there on the first Hangprinter Assembly Workshop at E3D HQ! It was a very special day.

Bonnie, Christopher, me (Torbjörn), David, Joshua, Sanjay, Chris, Christian, Clare, Rongsheng, Gregory, Rory, Adrian, Mary, Sally, and Richard on May 21, 2018

But I'm jumping ahead of the curve here. I arrived in the UK 15 days earlier, totally unprepared. I had never stayed in the UK before, and had a few things to learn: Like for example: There are 16 ounces in a pound. There are 14 pounds in a stone. There are 46 types of chips at the grocery store. There's conversion rates and adapters for most things. The British are exceptionally helpful.

French friends and E3D engineers Antoine and Raimbaud. Their practical help and explanations about British culture were indispensable

I took the first four days to assemble the ceiling unit and learn my way around the workshop. I got a desk near Greg's, and he would patiently show me where all the tools were, how to use them, how to make coffee, and how to use the British language. Every evening, Sanjay would come down from the office and join us. We would swap out my wiggly bearings and mount on some new parts, like a 24V power supply, compatible RUMBA electronics, and a Raspberry Pi for the web interface. Simple improvements, easily making the best ceiling unit yet.

HP3 ceiling unit with frame welded by Bruce the Blacksmith

Printing Chairs

With the help of a few 3d printed wedges and a rented scissor lift, we got it mounted and calibrated in a few hours. Eager to explore limits of the Super Volcano, we started off printing ourselves a simple chair shell:

Jump to 1:19 for a close up on the Titan Aero pushing plastic. It took 10 h to print, and turned out far too wiggly to sit on. Nevertheless a very promising first print.

I wanted to print more sturdy things, and experimented with egg chairs. I wanted the computer generated tool paths and the molten plastic strings of the FFF process to be obvious, instead of fighting layer effects or imitating surfaces created by other production processes. The raw look of infill and support structures was more what I was going for, so I sliced the egg chair without either perimeters, top layers, or bottom layers. This mode of printing was much less forgiving than normal printing, since hundreds of bridges get visible, along with any blob or gap caused by retraction and travel. All infill generators I tried assumed the support of perimeters and would draw loops right out in thin air. You basically need good planning and fantastic mechanics to make this naked printing look good.

I'm sure the FFF community will eventually get over trying to imitate smoothness when it can't. It will take some nicer chairs than these to convince everybody, but I guess it's a start. All but the smallest print have had loose bridges removed manually with a side cutter.

Reliability Experiment

I let people walk freely around the machine as it was running. Observations:

  • We had a total of 5 tripping incidents.
  • People trip when walking backwards, talking, and carrying things. Safety measures must account for such.
  • The machine rarely recovers by itself, despite the Mechaduinos being closed loop.

Nobody was hurt during this experiment. Better safety and recovery is now implemented in the Mechaduino firmware.

Hangprinter Assembly Workshop #1 With RichRap

Richard Horne joined us a couple of days before the assembly workshop. He brought his own Hangprinter with two very distinct features:

  • Its anchor positions were planned beforehand, removing the need of post mount calibration.
  • Its effector triangle was entirely 3d printed. Very sturdy and well designed!

See Richard's blog post about the RepRap birthday, the workshop, and his Hangprinter developments.

Instructing the first ever Hangprinter assembly workshop was the highlight of the month for me, since it is the mode of spreading that I've optimized the Hangprinter design for since the beginning. Observing how every little design decision played out was much like seeing the Hangprinter v1 move for the first time. First thought: Holy crap, it works! Second thought: Oh, I could improve this and this and this.

Detailed checklists for both instructors and participants proved very useful for keeping the workshop on track. All, our check points were ticked off in time, so I'd call the workshop weekend a success. The more important measure of success remains to be seen though: How much value the participants will manage to create with their Hangprinters? We keep in contact, so both machines and knowledge can enter practical use as smoothly as possible.

Both participant groups getting started on effector assembly

RepRap Self-replication 10 Year Birthday Party

And while we were sweating over self-replicating these machines, trying to get some geometric growth and viral spread going, various RepRap heroes start arriving for the birthday party. Among them the man who first launched the RepRap mother ship; Adrian Bowyer.

Image by Sally Bowyer of RepRap Ltd. CC BY-SA 4.0 Original image on Instagram

The whole RepRap Project, and in particular Adrian's text Wealth Without Money, has motivated me and the Hangprinter Project for a long time. Along with the other RepRap heroes in the picture at the top, he has done a great deal of the practical work that got us through the phase of 3D printing Without Money Because the Machine Was So Expensive. I'm very happy I got to meet them all on a day of so much machine self-replication in such a lively workshop. I hope we'll get the chance to meet again as RepRap continues to progress in the coming years.


In the following bank holiday I got the chance to visit Oxford and London's science- and natural history museums. I was surprised to learn that the UK once had the ability to launch its own space rockets, but then lost it. Like a Brexit out of space! Checking out London's Science Museum with Nikos and Sanjay was a great pleasure. The amount of engineering knowledge these guys possess is truly quite extreme.

Here they are in front of Stephenson's Rocket

Technical Developments

The original plan was to print something big during my last days, but I decided to prioritize technical development instead. The following factors combined into some serious ringing issues:

  • Very long lines (big print volume)
  • Stiff lines (Mechaduino firmware fixes let me run them stiffer than before)
  • High print speeds
  • Long and heavy copper heater block

This buddy was printed slowly, but still has lots of ringing behind the eyes. My camera broke, so I can show you neither the really bad ones, nor the much better ones, after the fix was applied. To fix the ringing issue, I implemented a block and pulley system who both reduced force in the lines and restricted xy-rotations of the mover. More technical info on my dev blog.

The HP3 is still mounted in E3D's workshop ceiling, and now in E3D's ownership! Watch these long moves to get an impression of the print sizes I'm hoping for. No pressure.

First move is 1732 mm long, the second is 2100 mm long. Both as close to perfect as we were able to measure by hand with measurement tape.

I'm sure you will get updated by the E3D Online account on Twitter when the big prints come out ;)

Make your new owners proud, little machine

I'm going to miss you, sunny Oxfordshire countryside!


That's all folks. Best regards,
- Tobben
Follow my journey on Twitter @tobbelobb

More information about the Hangprinter can be found here

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