Paddlewheel speed log

thingiverse

INTRODUCTION ============ This design presents a simple paddlewheel based speed log. Its working procedure is similar to those commercially available for boats and yachts, but scaled down for smaller craft. The incoming flow of water turns the impeller, with each paddle containing a small magnet. A basic electronics board counts each time a magnet passes the topmost part, providing a velocity reading proportional to the count. The intended use of this design is two-fold: it showcases these systems and provides a simple, inexpensive speed log for small DIY projects. Although using a small GPS could achieve similar results with greater accuracy, I developed this for a low-cost ROV (Remotely Operated Vehicle) used in underwater exploration, where GPS is not available. The code and schematics for the Arduino based electronics are freely available on my GitHub account: https://github.com/humbertomb/arduSpeedLog MATERIALS ========== * 1 x Upper part case for the electronics (printed, PLA) * 2 x Lower part case for the impeller (printed, PLA) * 1 x Impeller (printed, PLA) * 4 x Small circular magnets (5 mm diameter, 0.1 mm thickness) * 1 x M3 bolt 15 mm * 1 x M3 locknut * 2 x M3 washers BUILDING ======== I printed all the parts with a XYZ Davinci Jr using low infill (10%). The three case parts were printed in white though PLA, while the impeller was made from orange translucent PLA. I started by printing the impeller and re-drilling its axle hole to 3mm. Then, I glued magnets onto each paddle and washers into the axle hole using cyanoacrylate. Next, I printed the two lower part halves and the upper part. Finally, I glued them together using cyanoacrylate. After that, I fitted the impeller inside and pulled the bolt through its axle hole, securing it with a locknut. Be careful not to tighten the locknut too much, as this could prevent the impeller from spinning freely.