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.

Simplify3D Profile for the BCN3D SIGMA 3D Printer

Just a quick one - I thought some of you may be interested to test out a new profile for Simplify3D

I have shared my Version 5 Dual extruder profile for Simplify3D - this is for the BCN3D Technologies SIGMA 3D Printer. (Profile download the the end of this post)

Feel free to download and try it out if you want to experiment with the SIGMA and Simplify3D.

This is for Dual PLA at the moment, on the standard SIGMA with dual 0.4mm nozzles.

I have experimented with many more nozzle sizes and materials, so expect more profiles and tweaks in the future.

I wanted to see how more people get on with using the SIGMA under Simplify3D, so please do comment if you try it out - also please comment on what material / type and manufacturer you used / tried.

Above - Nervous System dual colour tree frog - very good model to test out dual extrusion printers - get it here

Above - Another great model for checking dual printing capability - The dual pen pot by Mark Durbin (MakeAlot) - Download the model here


One thing you will notice is that the tool change retraction is short, this is deliberate - so make it longer at your own risk! - I found that many complex dual prints would fail after many, many small retractions and rapid tool change-overs if the tool-change retraction was long (more than 6.5mm) - so it's shorter now, with added restart distance to make up for the ooze of a stationary tool.

The YouMagine Entry is also in open Wiki mode so anyone can edit it, and upload more profiles if you wish. If you make a new or improved profile, share and upload over on the same YouMagine page (Download here)

I'll have an update on using the BCN3D Sigma 3D Printer very soon.

Thanks for reading,

Rich.

High power hot-end for fast printing - dual resistor & easier thermistor

This is the first of a few new hot-end designs I have been testing, I mounted it to my new ‘Bling’ machine for some speed and temperature testing, it’s performing well, here is how I made it - 

I decided to try a new shape for the heater block, normally you want a low profile block with a short hot-zone, but I specifically wanted to try a triangular shaped block for a number of reasons / goals - 

• I wanted to mount 2 x Resistor heating elements in the block so a wide base made this easy.
• I wanted to try a longer heating zone to see how fast I could extrude.
• Triangle gives smaller mass at the top, hopefully to reduce oozing due to the longer heating-zone.
• I wanted to be able to easily wrap the block in PTFE sheet, a triangle gives a easy to wrap shape and is insulated at the top with two thickness of PTFE.
• For the future I want to be able to extrude fast @ 300 degrees C with less than a 4 degrees C temperature drop while printing solid layers.

Next I REALLY wanted to switch away from using the tiny dipped thermistors the size of pixi-dust with ultra thin connecting wires, they are such a pain to use and don’t really have many plus points apart from the low thermal mass/quick response. I now only use a ‘normal’ Axial style. I can fully recommend doing this, it’s 1000 x easier to build and much less fragile, I also think I get much better temperature reading stability, response time is fine.

HONEYWELL S&C / FENWALL  135-104LAG-J01 Link Here - 

Thermistor Type:NTC; Resistance:100kohm; Thermistor Tolerance:± 10%; Beta Value (K):3974K; Operating Temperature Range:-60°C to +300°C;

You can buy them from Farnell -  only £0.25p

I have used 2 x 10ohm Vitreous enamel resistors in parallel; this gives approximately a 5ohm load where you would normally use a single 6.8ohm resistor.

The resistors are either side of the nozzle, giving nice constant heating.

The axial thermistor is slightly above the resistors and is just touching the side of the nozzle barrel, this placement gives me a quite constant 3 degrees C lower reading than the inside of the nozzle throughout the temperature range, which is fine.

Wrap the thermistor body and legs in Kapton to insulate.

Use Aluminum foil or tape around the Resistor body, it should be a good tight fit in the block. 

All in place and secured with Fire cement.

The part make-up looks like this. (Ignore the PTFE washers; I didn’t use these in the end).

I also wrapped the heating block in a strip of 0.5mm PTFE sheet.

Still using PEEK in this design, I expect to remove this part in the next version.

All wired up using high temperature heat-shrink and silicon coated wires.

And assembled.

I added a small heatsink, but I doubt this is really required.

The PEEK block is only luke-warm to the touch even after 4+ hours of printing – Note I am using a small 40mm directional fan aimed at the PTFE.

I will do some more tests to see if I can switch off this fan and still keep a cool cold-end.

My Fan-duct for Greg's Linear bearing X Carriage is on Thingiverse here.

It’s printed just over 2Kg of material so far at ~160mm/Sec and it’s performing well; I’m really happy with it. All of the multicoloured Faberdashery printing in my previous blog update was done with this setup along with some ABS parts and build sheets.

I have not yet found an upper speed limit as I need to do more testing, but it manages to print PLA at 180mm/sec with only a 2 degrees C drop in temperature when doing whole build-plates of full infill layers.

I will be testing ABS more extensively with it over the next week and seeing how fast I can get it working with different materials.

My main observation now is that you do need to run this style of hot-end at a minimum of 80mm/sec, and I need a 1.5mm extruder reverse to make sure oozing is not a problem. At speeds lower than 60mm/sec it’s better to use a smaller heating zone/block.

Next time I will still use a triangular block but make it slightly smaller overall and a little shorter.

Thanks for looking, I would be really interested in any comments or opinions on high-speed printing and hot-ends designed for speed and also high (290+ temperature) - you'll see why in a future post....

Rich.