CELESTRON C8 XLT FOCUSER MOTORIZATION:

thingiverse

CELESTRON C8 XLT FOCUSER MOTORIZARION: All started when I found a couple of matched gears from a scrapped printer, that I though they could be used to motorize the focuser of my new C8 Celestron. As the bigger one was only 2mm thick, I decided to make a "sandwich" to hold it in in the knob axis. The smaller gear was installed on the axis of a standart RC Servo Motor, previously modified to remove the electronics, potentiometer and the stopping pin (For instance, you can see how to do this in Youtube: https://www.youtube.com/watch?v=lHIVY5-xWq4). A "must have" in the design was to be able to easily disengage the motor to be able to do manual focusing is desired, so this made things a bit more complex. Four 3D parts must be done: two to hold the focuser main gear (LowerGearHolder & UpperGearHolder) and two more to hold the servo motor system (ServoSupportBase & ServoSupport4Motor). The jpg files named "Description1 & 2.jpg" show the different parts and steps, while the other "Electronics.jpg" describes the electronics circuit I used to drive the motor and has three push buttons: left, right and fast. The LowerGearHolder is installed using the same screws of the C8 focuser orange plate. They are long enough. The attached files contain the images and the STL files. I used 1.7mm PLA, medium quality, 115ºC, 30% infill, five upper & lower layers, and supports for the LowerGearHolder. If you use PLA, remember to put a layer of paint or wax to avoid the humidity getting in to part as time goes by. The main gear I used has a diameter of 52mm, but the design can accept gear diameters between 50 and 56 mm. If you are able to generate 3D parts of quality, you can design your own gear set, or in Thingiverse there are many designs that can be leveraged to generate gears, for instance things:1604369, 24071, 26243, 5505, 40410, etc, and many others that use gears inside. The original rubber knob can be placed again on the UpperGearHolder, and to disengage the motor for a rough first focusing, just pull out a bit the ServoSupport4Motor, focus using the knob and then release the motor support and the spring (or a rubber band) will return the motor gear in the driving position, and you are ready.