Upgrades and printing with the BCN3D Sigma dual extruder 3D Printer

My update on using the BCN3D Sigma 3D Printer for the last 6 or so months.

Do check out the video for a more visual feast into the madness of my modifications :)

You can also watch it in HD over on my YouTube channel here (and please subscribe, thank you)

A few months back  Last year (2015), I posted about my first few weeks using the BCN3D Sigma 3D Printer, here is an update on some of the changes and how I have been getting along with the machine.

As I said in my previous video and blog post, the BCN3D Sigma is a really great 3D Printer. It has many of the key features people are looking for in a machine they need to produce 3D Models.

Because the Sigma is a fully built and tooled up machine, it's not really aimed at the low-end or to compete with the kit build market. That said, it's excellent value for money with the bonus of having dual independent print heads, it's a great 'production quality' desktop machine.

I have just now, in early 2016 spent my own hard earned cash on buying a Sigma, not something I do lightly. And I could not afford a brand new one, so it's actually second hand. I was very lucky someone in the UK wanted to sell it. (thank you so much for driving it to me, you know who you are, I am highly grateful and now use this machine every single day).

That's probably the best and most genuine endorsement I can give a machine. Spending my own money on a printer, now, when I already have a few is significant.

The Sigma is still the best built production machine I have used (so far) - finally on-par with my own custom 3D Printers I have built and still use over the many years of doing this.

I have done all the usual things with Sigma, printing fast and 'draft quality' to slow and fine layer models to examine the details that can be produced. I'm not so concerned with ultimate quality when 3D printing. I would much rather a fast and accurate, strong print using a fat nozzle.

All these dual colour pots were using 0.6mm nozzles and a fast print profile with 0.2mm layers.
The print time was under 5 hours for each one. The quality is not 'perfect' but more than good enough for kids to use and for 'practical' applications.

In fact I have a 5 hour rule, if I can't print it in under 5 hours, then I use a bigger nozzle, or lower quality or wait until the weekend (and then it may not happen). So for me, 3D printing is more about getting something that's accurate and strong, not ultimate quality.

Sigma can do quality, but with a change of nozzle size and pushing the speed, it also does fast too.

Dual printing is where this machine really stands out from the other 'dual extruder / dual nozzle' systems available. This is an area where I am most excited for FDM, Having useful models, and an ability to 'actually print almost anything' is a fundamental goal for desktop 3D Printing.

 Two ways to dual 3D print - Above bigger tool-change retractions and no purge tower.

 Or use a tower and avoid jamming up the hot-ends because of long retraction <<< Do this method!

Above is the Nervous System dual treefrog - a tricky one to dual 3D print. It was the second thing I printed on the new machine, right after the test calibration pattern (above). Both at 0.4mm nozzles, and a 0.2mm layer height, set to print fast (65mm/sec) - not ultra-fine quality, but a solid and fast 3D print in under 4 hours.


Like everything that's designed or configured for you, it's possible you will want to change or tweak things to make it easier for you to use every day. That's exactly what this update is about - my changes to the machine and what I have been printing for a few months.

Firstly I need total flexibility for spool sizes and all different types of coiled plastic. We don't quite yet have a universal spool size standard, or any sort of agreement on the ideal diameter of filament coils.

I found I could not fit 1Kg reels of filament inside the Sigma, they almost fit, and I even printed new spool adapters. But everything was just a little too tight fitting, and not easy to change out.

After some considerations, as this is a fully built machine that can't be taken apart. I opted for an external filament rack and to re-mount the bowden extruders outside of the machine. Sounds quite drastic, but it's a simple re-routing of the motors.

The upgrades were obviously 3D printed on the Sigma - and to keep everything as light as possible a painted wooden frame was built to take two spools at the back.

The other change was to provide more options for materials and nozzle sizes. The Sigma comes with 0.4mm brass nozzles fitted. If you want to print in filled materials or abrasive carbon fiber or glow-in-the-dark then you really need a hardened nozzle.

Sigma on the left and E3D V6 on the right

I was also finding that the second print head was starting to be used more for support materials, rather than a different colour. Dual colour prints are nice, but the second head is great for using as a different support material. And I found that a 0.6mm nozzle allowed me to print support materials faster and with more success.

I can now swap out nozzles for almost any size or type. I leave a 0.6mm on the left and a 0.4mm on the right. This way I can print fast or fine or with dual materials - very complex models.

On the prototype machine I added a simple strip of Kapton to catch stray 'noodles' still a good thing to do to any Sigma.

On the new Sigma, you can fit these 3D Printed stiffening supports, this helps the silicone strip wipe off any excess plastic, and reduces the chances of noodles being pulled out and onto your build platform.

I'm really happy with the Sigma, and I can't wait to hack it some more.

BCN3D Technologies tell me that they are about to fully release the entire machine and even all it's manufacturing secret's as a complete open-source package. (I'll link here when that's announced).

* EDIT - 26/05/2016 - BCN3D have released everything, check out the press release here

They seem very serious about the Open-Source route, and don't sound like they are holding anything back at all.

Thanks for reading - and watching (I do go into more detail about the changes in the video).

Until next time.

Rich.