One of the key features of the Spanish BCN3D Sigma 3D printers is the system of two independent printheads called IDEX. It consists in the fact that the heads are installed on separate carts, moving together in the Y and Z axes, and separately in the X axis. This opens up many interesting possibilities for users, unavailable in other FDM / FFF desktop 3D printers: they can print details with two different colors, they can use building and support material, soluble in water, they can also print two sets of details simultaneously, on a table divided along the work table.

For some time we have been able to work on the flagship model BCN3D – Sigma R19, equipped with an A4-shaped work table (210 x 297 mm) and the ability to print details with a maximum height of 210 cm. The device has been made available to us by Global 3D – an authorized distributor of BCN3D devices in Poland.

Sigma R19 is as interesting as the simple calibration system for the work table and printheads, which is important because they are completely independent of each other. The 3D printer is controlled by a color touch screen located in the lower right part of the device. After starting the device, we have three options to choose from: choosing the 3D model on the SD card and starting 3D printing, entering the tool section and managing the heating of the heads or table.

We will deal with the second section, i.e. the tools. After selecting the section, four more options appear: changing the filament, calibration, maintenance (e.g. a simple procedure for cleaning the printheads) and 3D printer setup (e.g. choosing the language version).

Changing the filament is very simple and described in the previous article. First, we choose the head in which we will exchange the filament, and then its species. We can load different types of material into each of the heads. A wise choice would be, for example, to install building material in one (e.g. PLA, ABS) and support material, water-soluble in the other (e.g. PVA or BVOH), but if someone would like to experiment, they could theoretically print from nylon and PETG or any other configuration of this type …?

After choosing the CALIBRATION option, we have another three options to choose from: printing surface calibration, priner calibration and manual calibration. In this article we will focus on the first two – the simplest and most often used by the user at work. We start with the first one.

After activating this option, the 3D printer will probe the height of the printhead relative to the table using a sensor installed on the edge of the fan casing. After collecting data, the display will show how much should you turn the knob under the table to raise or lower it?

3D printer checks if our regulations have an effect? If so – the process is terminated. If not – we get further instructions for adjusting the table height.

The next step is to adjust the height of the printheads relative to the table.

The 3D printer heats the printheads and asks to clean the filament residues.

Later, device asks to apply a thin layer of Magigoo glue to the table that comes with the package. For now, I decided to work with another proven adhesive – NeedIT. It is in the form of an atomizer and is characterized by great performance (although its packaging is quite inconspicuous …).

When we go further, we raise the table to the head using the two arrows displayed on the left side of the display (do not turn the knobs under the table !!!). Between the printhead and the table, put a feeler gauge, which we get in the set. In the old custom I used a classic business card …

The head should be separated from the table to a height of approx. 0.1 ~ 0.15 mm. When we achieve this, we conduct a test.

The 3D printer asks us which line printed best? We choose and move on …

Repeat the process for the second head …

The next stage is extremely important – we calibrate the heads relative to each other. If we do not carry out this stage correctly, two-color prints or those using support material will go wrong – the heads will not hit each other in the right place on the detail …

We are printing another test …

We check which pairs of lines printed from both heads match each other best and select the appropriate value in the 3D printer menu. In my opinion, pairs 5, 6 and 7 came out best, so I chose the middle one.

If none of the lines is paired, we must repeat the procedure until successful. First, we choose the closest pair of lines and repeat the process. Finally (the second – third time) manages to achieve the effect as in the picture above. If not – we can do something like this …

The tower on the left was made of poorly calibrated printheads, while the tower on the right was made after correct calibration. The layer shift in the left tower is approx. 1 mm.

The last stage of calibration is the positioning of the heads relative to the Y axis.

We print another test and check line compliance. We choose the best pair and confirm. Calibration is complete.

Finally, all the above tests take place on different parts of the work table, so you do not need to remove prints immediately after carrying out.

Paweł Ślusarczyk
CEO of 3D Printing Center. Has over 15 years' experience in buisiness, gained in IT, advertising and polygraphy. Part of 3D printing industry since 2013.

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