4- The box , 3D realization

The printing of the CALIBREX box requires more than 8 hours of printing with layer height set at 0.2mm and 20% of printing on the two 3D printers tested. The servo motor palette must be printed with White plastic, the M42 female screw ring must be printed with more care, so a layer height of 0.15mm or even 0.10mm is required with a filling rate of 100% for maximum rigidity.

An overview of the closed CALIBREX calibration box without optics and without electronics, black PETG printing, prusa MK3 i3 3D printer – Pierre Dubreuil.
Exploded parts of the CALIBREX, the M42 ring and the slide are to be glued with epoxy glue once the parts have been cleaned. The servomotor palette is not visible here. The M42 ring is to be printed in 0.10mm or 0.15mm to reach the fineness of a screw thread necessary for screwing in an M42 Male / 2 ″ flowing ring to buy in metal.
The only part to print with White wire is the palette, but it is possible to print it in Black and paint the central reflection area in white afterwards. Here installation of the pallet on the ServoMotor

The files necessary for 3D printing in STL format can be downloaded from the links below. The nomenclature number is also indicated:

Printing of the CALIBREX case in black PETG, 3D printer prusa MK3 i3 – Pierre Dubreuil.
Printing media placement area.
The supports calculated by PrusaSlicer.
The cover placed on the Prusa slicer went for 3 hours 55 minutes of printing with my old Vertex K8400 print density 20% and layer thickness set at 0.2mm.

4- Control software


As you already know, the Calibrex module is equipped with an electronic card, the manufacturing of which we have just seen, with the list of necessary components, and above all the very simple manufacturing circuit board, which is equipped with an Arduino “nano”. You can get it on the net easily and for a very small fee of a few euros.

It is necessary to install the interface IDE Arduino on the Arduino site, you take the latest version 1.8.10, it is necessary to connect your Arduino “Nano” by a USB cable (mini USB socket on the side of the Nano). Finally configure “nano” in the type of card, in the help this is well explained.

Finally once connected select “file”, “open” and you access the “Spectro_nano_embedded” directory. In the directory there are three files (CPP file, H file and Arduino file) you will have to click “Spectro_nano_embbeded.ino” which is the arduino file.

1- Open the Spectro_Nano_embedded.ino file.
Note the Messenger.cpp and Messenger.h files must be in the same directory.
2- Connect the arduino Nano to the computer via USB and upload the driver. (Arrow at the top left)


Once powered, three modes selected with the switch of the box are then available.

1- The local operating mode, by successively pressing the push button on the box, the color of the multicore LED determines the commanded function, when starting the Arduino the “Clear” function is selected.

Color of the
Multicolored led
Pallet positionDenominationUVEX Fonction
light offopenedClearSpectrum acquisition
RedclosedNeonwavelength calibration
Green closedFlatInstrumental response

2- The remote mode allows with most astronomy software (Maxim, Prism …..) to remotely control via the USB cable, the 4 functions described above. In this case, the red power LED flashes quickly, indicating that the connection is well established between the PC and the Arduino. Jean Luc has programmed an Ascom driver which allows the electronic card to be connected to most astro software for amateurs. By choosing the wheel driver with ASCOM spectro filters you can then select the different functions (“Clear”, neon, flat, close acquisition).

Ascom filter wheel driver – ASCOM.Spectro for controlling calibration lamps
Dialog box under Prism which allows you to control the activation of CALIBREX calibration lamps.


For those who do not use Prism, MaximDl software …. Pierre and Jean-Luc have developed the Calibrex control application in C #, a small application for dialogue with the electronics of the nanoArduino at the heart of the caliber. The Calibrex Control V1.0 application runs on its own and updates automatically, it only needs the SpectroWeel ascom driver installed. Once connected to the driver, the 4 buttons allow you to control the 4 previous functions, the active function is very easily visible by the flashing of the colored rectangle to the right of each button.

Par défaut à la connection de l’application la fonction clear est sélectionnée

CALIBREX control v1004
By default when connecting the application the clear function is selected

1- Introduction

What is it about?

Calibrex combines in a single module 42 mm thick, a calibration system and a slot tracking system compatible with UVEX 3, all in 3D printing.

3D model of the Calibrex case here in red assembled with the UVEX 3 in gray.

UVEX claims to be an easy to build instrument. It uses 3D printing for mechanical production and uses standard components that can be purchased from companies like ThorLabs (for mirrors, the network, the lens). At the origin of the project, UVEX is perfectly integrated into the Shelyak Instrument system, the slot, the guide cube and the calibration box are those proposed by the company for the ALPY 600 spectroscope. UVEX being a low cost DIY project (Do it Yourself), it was natural to offer a Guidance and Calibration system in 3D printing, only the remaining slot to order from the company Shelyak.

In situation, UVEX 3 + Calibrex, installation on a C11, Zwo Asi 178MM guide camera.

Thus was born the Calibrex project which offers a single compact box which combines the functions of slit guidance and calibration with Argon / Neon lamp (lamp present in choke blocks for fluorescent tube) and a Tungsten lamp.

Model n ° 2 which equips the ALPY600 spectroscope in Basic version, installed on the 3D printing support of the UVEX 3.
Neon / Argon lamp present in the ignition choke of fluorescent tubes. These starters for a few euros provide a good light source necessary for the calibration of the spectra.

L’attribut alt de cette image est vide, son nom de fichier est guidage_fente_atlas-C2019y4.jpg.
Image of the guidance, Comet field C / 2019 ATLAS Y4 April 04, 2020 – C11 + Calibrex – Camera ASI ZWO 178MM 2s of 4×4 bin pose.
Spectrum of the internal neon calibration lamp in the caliber, 30s of installation UVEX 300 rpm + ATIK 314L + bining 1×1

The electronics are based on Arduino Nano which contains a microcontroller for flash memory and a mini USB port. The lamp control program is therefore saved in the arduino. The control of the lamps and the tilting of the reflector is carried out either by direct control via a switch on the side of the box, or by software via a dedicated ASCOM driver, filter wheel type driver.

Under the hood, on the left the Arduino Nano, the transformer, the connectors, on the right the servo motor with the paddle before mounting as well as the Relco lamp. Note the white circular arc mounted on the servo motor allows to obscure the telescope field during calibration. Here you have to paint it black and keep white a central area of ​​a few millimeters in the center. This simulates the opening of the field at F8. Thus the lines of the lamp of the calibration lamp are thinner which gives a more precise calibration.

A switch on the side of the box selects the remote mode, and the manual mode. In remote mode the switch is deactivated, the command is made exclusively via the CALIBREX USB port. The clear position allows to realize the spectra of the targets as well as the autoguiding, in neon position the ArNeon calibration lamp is on and the palette obscures the beam of the telescope, for the flat position the tungsten lamp is on, and finally in closed position no lamp is lit but the palette obscures the field of the telescope.

Ascom filter wheel driver – ASCOM.Spectro for controlling calibration lamps

From the Ascom driver, you can control the Calibrex box remotely, making it compatible with Remote mode. The advantage of diverting a filter wheel driver and being able to automate the alternation between object spectrum and calibration sequence acquisition in the same way as a three-color imaging sequence via the software automation interface. acquisition of the Prism or MaximDL type.

Boite de dialogue sous Prism qui permet de contrôler l’activation des lampes de calibration du CALIBREX.
A team effort, the Nice people, from left to right, Stéphane Ubaud, Alain Lopez, Jean Luc Martin, and Pierre Dubreuil.