Modeling Extruded Cuts and Pockets for Nuts and Screws

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When we 3D modeled and printed the gears we used, we had to take into account the gear may slip off its axle (either the stepper motor rod or the aluminum rod we used). To make sure that this did not occur, a nut and screw need to be attached to the gear, and the screw needs to come into contact with the axle to assure the gear will turn with its axle. There are two different methods we used to accomplish this.

Extruded Cut Method: This is a fairly common method. First I made an extruded cut into the base of the gear. The cut should be in the shape of the nut being used. An additional circular extruded cut needs to be added for the screw to thread into. An example of the extruded cut we used is seen below:

12tgear wextrudedcut.jpg

We used extruded cuts for the two 12 teeth gear that were directly attached to stepper motors. The extruded cut method is slightly easier to model than the pocket method but less secure. For the larger gear which was attached to the aluminum rod, we had to use the pocket method for the extra security

Pocket Method: This method is unique, and involves three separate extruded cuts. A diagram for a gear we modeled and used with the pocket is seen below. First, we extruded a rectangular prism off of the base cylinder of the gear. An extruded cut in the shape of the nut was inserted into the middle of the rectangular prism. A rectangular extruded cut is added to access the nut-shaped extruded cut, so it is very easy to insert and take out the nut from the gear. Finally, a circular extruded cut is added perpendicular to the nut-shaped cut sot the screw can easily thread through it.


The extra security the pocket method brings was crucial to our project. The 36-teeth gear that the pocket was added to was the focal point of the mechanical portion of our sunlight alarm, and we could not afford any inefficiencies.