My astronomy project:
Design of a 3D-printed filter wheel

Content:

1. CAD design of a filter wheel
2. Chassi
3. Stepper motor
4. Gears
5. Shaft and Roller bearings
6. Home position sensor
7. Lid
8. Off-Axis guider
9. To be continued

Note:
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2: Chassi

A stable chassi is important to hold the different parts together with high precision. It will be interesting to see if plastic can achieve these demands.

Chassi:

Early version of the chassi that hold the devices together. The rectangular opening is 40 x 28 mm. In center something that holds the shaft to the filter wheel must be added. The thickness of this chassi is 10 mm but have to increased it to 12 mm later to make enough space inside, the lid add 5 mm more. The bottom and walls are 3 mm thick.

The filter wheel must fit inside here. There is 1.5 mm space between the chassi's bottom and the wheel. The plan is to incorporate an off axis guider in the lid, that make it more compact compare to have them separated. It must be implemented a home positions sensor too. A start point that the stepper motor can synchronize to and then calculate how many steps to do when changing filters.

3D-print:

The chassi 3D-printed, some mistake of course but I could use it for test purpose. It must be really stiff because the camera and accessories are mounted on this and give a downward force to it. Too weak and it will bend.

The bottom side of the chassi. This side points against the camera. It's important to have the filters as close as possible to the camera to reduce vignetting problems. The filters surfaces are 5.5 mm behind the this backside.