A view of all the mechanical parts constituting the UVEX spectrograph: :
Files needed for 3D printing in STL format can be downloaded from the links below. The name of the nomenclature is also indicated:
UV01 : housing
UV02 : cousing cover
UV03 : slit tube
UV04 : slit support
UV05 : slit ring
UV06 : clear slit interface (optional)
UV07 : ATIK camera mount
UV08 : ZWO camera mount
UV09 : M1 support
UV10 : M2 support
UV11 : guide for M1 and M2 (2 pieces)
UV12 : grating support
UV13 : grating position lever
UV14 : ATIK314L camera mount
It is important to be careful about choosing the material for printing. PET-G was selected for the realization of the first versions of UVEX. But it is essential to choose a material that is very opaque to light. Often the pieces look opaque to the eye, but this is not the case in the infrared.
PET-G reinforced with carbon fibres (at 20%) is a better option in terms of rigidity and opacity, but your printer must be able to use this type of wire (choice of nozzles, adjustments, etc.).
The lest image shows a plate made of material that is transparent to light in the deep red (it is lit from behind with a powerful lamp). It is almost impossible to operate an astronomical spectrograph if the structure that constitutes it is not lightproof. This is a critically important point.
If the light-tightness of the housing is still insufficient, resign yourself to covering the body of the spectrograph with one or more black cloth(s), as in the photograph below:
Experiment with the materials that suit you best, and with the slicer settings of your choice too. This is an area where everyone’s experience and mastery of their own equipment matters most. Note in the next image the arrangement of reinforcements needed around the mounting holes of the two mirrors and the grating.
It takes about 10 hours to print the main box with a 20% density. .
A 3D printed object is built layer by layer, each layer being deposited on the previous one. For some parts of the pieces, this “previous layer” simply does not exist, and it is therefore not possible to build the following layers in the air. Temporary support must be defined by the slicer software in these situations, which can be removed once the printing is complete. Some software automatically positions the support for you and makes suggestions. Opposite, the UVEX box with supports voluntarily added at the level of the openings, for example.
The following views show the positioning of the parts on the printer bed. All are made with a 0.2 mm layer fineness, except for the clear slit holder UV06, made with an accuracy of 0.15 mm. If you use this piece, be careful to print it with the angled surface that receives the metal slit on the printer bed (this is the only way to have a very smooth surface). It is recommended to print the case with 3 perimeters for rigidity, while for other parts, 2 perimeters are sufficient.
A short film showing a UVEX box in progress.
A number of holes are tapped M3 and M4 (for example the holes for fixing the cover on the housing). This is a delicate operation that must be done with care. It is recommended to use the set of 3 taps in order for each diameter, and to push “rather firmly” before turning the tap holder carefully and without risking the material (only the M2 holes of the clear slit UV06 part are tapped by the screws themselves). It is necessary to push throughout the first tapping, taking care to stay as much as possible in the axis of the hole, otherwise the tap may slip. It is a good idea to train on a spare part for the first tapping.