Mechanical Designer — Tether Power/UPS Unit Redesign (Drone Ground Station)

Project Overview We are looking for an experienced mechanical designer to redesign our tether power unit (TPU) which houses the spooling mechanism, power electronics, and UPS/battery backup system for a tethered drone ground station. The unit lives in a Pelican-style case. The TPU redesign integrates a new tether reel unit along with a UPS conversion system and an additional backup UPS battery, while fixing a list of known mechanical issues from the legacy design. All new internals must fit within the existing box form factor, with a total weight limit of 32 kg. This is a fixed-price project. Deliverable is CAD files and drawings only. We may need some DFM/testing support as we prototype and build the unit, which can be discussed after completion of the deliverable. Scope of Work Review legacy TPU tether unit design (CAD + documentation will be provided) and the new unit specs Rearrange internal electronics and spooling mechanism layout to fit the new components inside the existing enclosure Redesign the spool/cable-winding subsystem end-to-end (see "Legacy Issues" below) Integrate power/current monitoring, display, switches, and LED indicators as native panel-mounted features rather than add-ons Redesign the front access panel for proper, repeatable fit to the Pelican body Redesign panel fan/vent integration for adequate cooling with proper environmental sealing Design a clean dock/mount for the UPS battery pack on the panel Produce a fully detailed 3D CAD model of the redesigned assembly Produce 2D manufacturing drawings with GD&T for all custom parts Provide and specify any 3D printed components and materials Provide a BOM listing all custom parts, fasteners, and off-the-shelf components used Deliver files in SolidWorks format plus neutral formats (STEP, PDF) Legacy Issues to Resolve Spool motor failures — current motor likely undersized on torque and/or poorly mounted; fails at a high rate Cable entry/pulley friction — excessive friction at the cable entry and pulley causes breakage and motor stalls Oversized/overengineered spool shaft — shaft is bulkier than needed; U-clamps are poorly designed and often misaligned, adding unnecessary torque load Motor engaged during unwinding — motor stays engaged while cable pays out, adding unnecessary stress/wear Power/current monitoring — was bolted on after the fact, not properly integrated into the system Display monitor — same issue, add-on rather than integrated Panel fans — functional but too loud, and don't properly seal the enclosure interior Main top panel fit — never sits properly on the Pelican body; difficult to install and secure Desired New Features UPS battery docks cleanly onto the front panel Proper switch and LED indication for main AC power and battery fallback status Simple integrated screen mounting and integration Inline or geared motor assembly with proper bearing support to minimize side and axial loading on the motor shaft Proper motor selection (adequate torque/duty cycle margin vs. legacy design) Robust mechanical or electromechanical cable winder — self-reversing screw-type level winder preferred, to eliminate misalignment issues Constraints Must fit within the existing Pelican case form factor (no enclosure redesign) Total assembled weight limit: 32 kg Must accommodate the new PowerTug unit and UPS conversion system plus an additional backup battery What We'll Provide Existing CAD model and/or drawings of the legacy STS-UPS unit New PowerTug unit and specifications UPS conversion system and backup battery specs UPS battery pack dimensions/interface details Electrical specs for the tether (voltage, current, conductor gauge, connector type) Ideal Candidate Proven mechanical design experience with cable/spool winding mechanisms (level winders, motorized reels) Experience with enclosure/panel design for field-deployable or ruggedized equipment (Pelican-style cases a plus) Comfortable selecting motors/gearheads/bearings for continuous-duty, cyclic-load applications Experience with 3D printing, carbon fiber and G10 manufacturing and design Comfortable with GD&T and producing manufacturing-ready drawings Bonus: experience with drones, tethered UAV systems, or ground station hardware Bonus: experience integrating small embedded displays (Raspberry Pi or similar) into panel-mount housings Deliverables Complete 3D CAD assembly of the redesigned tether unit 2D manufacturing drawings (PDF + native + STEP) with GD&T BOM with part numbers/sourcing links for off-the-shelf components (motor, gearhead, bearings, battery dock, fans, connectors, etc.) Brief design rationale document explaining how each legacy issue was addressed and how new features were integrated How to Apply Please include: Relevant past projects (cable/spool winding mechanisms, ruggedized enclosure design, or similar) — portfolio or CAD samples welcome Your proposed fixed price and estimated timeline Any clarifying questions about the legacy design, PowerTug integration, or weight/form-factor constraints