Center-to-center distance: 5.908 in | Cross-section width: 0.300 in | Material thickness: 0.094 in Nylon 6/6
Design Decisions
Implemented a dogbone geometry to reduce weight while maintaining strength. 1.000 in radius fillets minimize stress concentrations between the pin joints and central body. Hole diameters include 0.006 in clearance to account for laser cutter kerf and ensure proper fit with shoulder screws.
Engineering Analysis
Applied load: 155 lbs | Net cross-sectional area: 0.0276 in² | Resulting stress: 5,616 psi
Using Nylon 6/6 yield strength ≈ 10,000 psi → Calculated FoS: 1.78
Failure predicted as tensile rupture at the narrowest cross-section. Pin-hole bearing stress also evaluated to ensure sufficient wall thickness and prevent tear-out failure.
Load Test Validation
Results
Design load: 155 lbs | Link successfully sustained full design load
Measured elastic deformation: 0.062 in (0.93%) — well below the 10% failure threshold.
Predicted deformation: 0.107 in | Actual: 0.062 in | FoS: 1.78 Validated
Reflection
The link exhibited lower deformation than predicted by the simplified FL/EA model. This difference is likely due to the dogbone geometry, where the widened ends and fillets increase the average stiffness compared to the uniform cross-section assumed in the analytical model. Selecting Pin 4 also reduced the required link length by over 12% compared to standard Pin 6 designs, resulting in a lighter and more competitive component.
System Overview
The receiver is composed of three primary subsystems: an RF Tuning Circuit using an LC resonant network and varactor diode to select the desired frequency, a Receiver IC (TDA7088T) that demodulates the FM signal and extracts audio, and an Audio Amplifier (LM386) that drives an 8Ω speaker.
RF Tuning Principle
The radio selects stations using a resonant LC circuit. By varying capacitance using a varactor diode, the circuit shifts its resonant frequency, enabling the receiver to automatically scan across the 88–108 MHz FM spectrum.
Audio Amplification
The demodulated audio signal is amplified using an LM386 low-voltage audio power amplifier. Default gain: 20 (26 dB), capable of driving an 8Ω speaker, designed for low-power portable audio applications.
Assembly & Manufacturing
The PCB was populated with 40+ through-hole electronic components including resistors (5% tolerance), ceramic and electrolytic capacitors, RF tuning inductors, and integrated circuits. Proper component orientation and clean solder joints were essential for reliable circuit operation.
Challenges
One challenge was ensuring the inductor coils used in the RF tuning stage were properly formed and spaced, as coil geometry directly affects inductance and therefore the tuning range of the receiver. Additional troubleshooting included verifying solder joints and confirming signal flow through the amplifier stage using a multimeter.
Reflection
This project provided practical experience with radio frequency circuits, signal demodulation, and PCB population. It helped bridge theoretical concepts from electromagnetic and circuit theory with real hardware implementation, reinforcing how inductors, capacitors, and amplifiers interact within a communication system.
Current Progress
The project is being completed component-by-component, beginning with the core structural and rotating elements. Current completed components — crankshaft, piston, and engine block — establish the primary kinematic relationship between the pistons and crankshaft, converting reciprocating piston motion into rotational output.
Assembly Stages
1. Lower Block Assembly — integration of crankshaft, pistons, and block
2. Upper Block Assembly — cylinder head, valvetrain, and camshaft components
3. Final System Assembly — belt drive, accessory components, and intake/exhaust systems
Planned Components
Rocker Arm, Cylinder Head, Exhaust Manifold, Air Filter, Camshaft, Rocker Spring and Valve, Belt Wheels, Valves Cover, Front Cover, Oil Pan, Turbocharger, Intake Manifold, Bushings and Camshaft Retainer
Mechanical Principles
The engine operates using a crank-slider mechanism where piston motion is transferred to the crankshaft through connecting rods. Piston position is governed by:
x = r·cos(θ) + √(l² − (r·sin(θ))²)
where r = crank radius, l = connecting rod length, θ = crank angle. This relationship determines stroke length and volumetric displacement.
Goal
The completed project will result in a fully detailed V6 engine assembly capable of motion simulation, providing a deeper understanding of engine architecture, mechanical linkages, and multi-part CAD system integration. The final assembly will consist of 16 engineered components across 3 major assembly stages.
