[Sensor Sub-Component] Water Level Sensor Housing

thingiverse

This Thing is a Two-piece assembly consisting of the Top Tube and Bottom Tube that combine with my Sharp GP2Y0A21 IR Sensor Housing and IR Sensor Puck to form an Infrared Water Level Measurement sensor. The two pieces fit together securely in a friction pressure fit, with perforations for visual indication of the puck, water level, and any debris. The top three threads are 4mm ANSI M Metric threads at 17mm deep and connect the IR Sensor Housing to the tube structure. I would re-design this part by removing side perforations and replacing them with a vertical "window", either completely plastic-free or with a transparent material, which would eliminate ripples in the water body from affecting the puck and sensor reading. I might add an "intermediate" tube section to extend the housing up to 80cm long (Sharp's listed max distance for the IR sensor). I will coat the part in an inert non-toxic lac-based spray enamel to prevent ABS plastic degradation in water. Instructions Design Like all of my parts, I used Autodesk Fusion 360 CAD software and UP slicer program on an UP Mini printer. I sketched a cylinder with 54mm diameter in Fusion 360 then created a circular pattern to repeat the perforations. A circle was cut from the cylinder, saving time. I imported the IR Sensor Casing and created screw hole cylinders then cut them in half and exported them separately. To emboss (deboss?) text onto the cylinder, I created a text sketch in midplane of the cylinder then extruded it "to" the inside of a shell. A dedicated Ebbos feature would be nice, but until then this is Autodesk's recommended method. Because of the UP Mini printer's height limitations (4.75"), I chose to split the part into two pieces. This allows an intermediate extension part to be added between the top and bottom tubes. The "Max Water Level" text indicates the minimum distance the puck needs to be for Sharp IR sensor function. Printing The printing of this Thing is somewhat tricky due to its complex shape in terms of support structures. I recommend printing the Top and Bottom pieces vertically, side-by-side, to prevent warping of the edges if they were printed on their sides. Enabling support options in your slicing program can help prevent warping. Minimum layer height (I used 0.2mm) is recommended for printing text and threads but can take around 8-10 hours at moderate settings; using a .1mm layer height could potentially double the build time. Preparation ABS plastic tends to degrade in water, "leaching" contaminants into the liquid, so thoroughly coating the entire part with sealant is advised. I used Clear Shellac Spray which has the benefit of being non-toxic and lac-based (an insect resin) but may not be suitable for chemical-sensitive environments where contamination must be avoided completely; Acrylic Coating could provide a safer option in those situations.