Mailbox delivery notifier

thingiverse

Before designing this project, I set four key criteria. Firstly, the mailbox delivery notifier had to be discreet for both the postal carrier and neighbors - no visible wires or electronics that could cause anxiety. Secondly, I needed to easily detect the state of the box contents (delivery versus non-delivery) without alerting the neighbors or passersby. Thirdly, it had to be reliable, durable, and simple to reset back to an untriggered state. Lastly, it required being inexpensive and low-tech with a straightforward mechanism, preferably no strings, springs, or cables. Photos Commentary: Looking at the underside view of the mechanism, you'll see the door on the right and the flag on the back of the mailbox at left. When the door opens, it swings down on its hinges and pushes in the plunger at far right. This action pivots the pivot rod arm which retracts the flag release latch bar at far left. Note that there's a short ¼" bolt at the bottom right on the back side of the mailbox, serving as a stop when resetting the mechanism. To reset the mechanism to an untriggered state, simply reach around the back of the mailbox with one hand and rotate the flag assembly clockwise until the assembly's right arm hits the bolt head. Then, reach under the mail box door with your other hand and pull the trigger mechanism back into position. The flag release rod easily slips back through the hole in the flag assembly and holds it in place. You'll need to print the following parts to construct the assembly: 2 x latch_channel_2.stl (holds door latch and flag release in place, at opposite ends under the mailbox) 1 x door_latch_2.stl (positioned beneath mailbox to detect opening of mailbox door) 1 x flag_release_2.stl (retracts to allow flag to move) 1 x short_link.stl (connects door latch and pivot rod) 1 x pivot_rod.stl (rotates about center to convert door_latch push into flag_release pull) 1 x gear_axle_2.stl, and 1 x gear_axle_bushing_2.stl (holds pivot_rod in position and allows it to rotate) 1 x long_link.stl (you need to customize to length needed to connect the two ends of your individual mailbox - mine was 10.3 inches between the two hole centers) 1 x flag_2_(1_of_2).stl (print with filament the color of the mailbox) 1 x flag_2_(2_of_2).stl (print with filament color that contrasts to the color of the mailbox) 1 x counterbalance_(1_of_2).stl 1 x counterbalance_(2_of_2).stl (holds 7 pennies to provide the weight which makes flag pivot upright when triggered) 1 x clip_post_for_flag.slt (print horizontally with support for optimal strength) 2 x clip_post_long.stl (used at both ends of the short_link connector) 3 x clip_post_short.slt 7 x eclip_long.slt (2 of these are used on the clip_post_for_flag) You'll also need to provide a ¼" hex bolt that is ½" or so long to make the flag stop, and 5 #6 screws to attach the mechanism to the underside of the mailbox.