The final design integrates all the functional requirements into a compact, modular system that enables consistent and efficient tack welding of honeycomb rings. Built with operator ergonomics, weld repeatability, and component alignment in mind, the system brings together mechanical, electrical, and control elements in a synchronized workflow. The CAD view below shows the complete setup, including the actuator and controller interface, spring-loaded tip holder, and multi-tip electrodes—all designed to work seamlessly with the existing power supply. Each of these elements plays a key role in ensuring reliable weld quality and ease of operation, as detailed in the following sections.

Components

Multi-Tip Electrode

The multi-tip electrode is designed to weld five honeycomb cells simultaneously, significantly reducing the time and effort required compared to traditional single-tip methods. Each tip is spaced exactly 1/8" apart to match the cell pitch of the most common honeycomb configuration used by our sponsor. To ensure precision, the tips are inserted via a press-fit into a machined copper block, enabling reliable alignment without the need for complex fixtures or calibration.

After fabrication, each tip undergoes a two-stage bending process. First, the copper rods are side-bent 30° using a manual jig, followed by a 52° downward bend using a custom 3D-printed mold. This geometry results in a consistent vertical offset of approximately 0.42 inches, allowing the tips to enter the honeycomb cells at an optimal angle for effective resistance welding. The tip geometry is standardized using a custom sanding jig with controlled tapering angles to fit cells as small as 1/32". This combination of precise spacing, repeatable shaping, and modular assembly ensures both weld consistency and ease of maintenance.

Manufacturing and Tooling

Actuator and Controller

The actuator and controller system replicates the squeezing motion required for tack welding by converting rotational motion into precise linear displacement. The system is built around a NEMA 11 stepper motor coupled with a T6 lead screw (1 mm pitch and lead), allowing for fine motion control with a minimum step size of 0.01 inches—critical for aligning tips within the 1/8” honeycomb cells. To achieve this resolution, the motor operates in ¼ microstepping mode, controlled by a robust ZK-SMC02 PLC. This setup ensures both positional accuracy and repeatability, while maintaining compatibility with industrial standards.

During operation, the user selects the desired cell size using a potentiometer and confirms it via a push button. The actuator then moves the tips to a pre-set distance for positioning. A foot pedal triggers the final welding motion, pressing the tips together and activating the weld once proper alignment is confirmed. This multi-input interface not only enables ergonomic, hands-free welding but also separates setup from execution, improving safety and reducing operator workload. The system was designed for seamless integration with the custom welding table and can be adapted to future cell size variations with minimal reprogramming.

Welding Power Supply Connection

To ensure high-quality welds, our system interfaces directly with the sponsor’s existing AMADA CD 125A stored energy power supply. This unit delivers precise, high-current pulses through capacitive discharge, making it ideal for resistance welding in tight spaces like honeycomb cells. Our design includes custom-fabricated mounts that securely fasten the welding cables to the multi-tip electrodes, providing a stable electrical connection during operation. The tips themselves are made from RWMA Class 2 copper-chromium alloy, selected for its conductivity and durability under repeated thermal cycles.

The cable mounts are currently 3D printed in PLA, but for improved longevity, we recommend transitioning to ABS or another high-temperature-resistant polymer to prevent deformation over time. The mounts also act as an electrical insulator and structural support, minimizing cable movement and ensuring consistent current delivery across all five tips. This connection strategy avoids the need for any internal changes to the AMADA unit, making the system plug-and-play within the existing manufacturing infrastructure.

Spring Loaded Tip Holder

The spring-loaded tip holder plays a critical role in maintaining consistent welding force across all tips, even under thermal deformation. Designed to be mounted directly onto the linear actuator’s carriage, the holder features a hinge mechanism that allows it to pivot slightly during compression. A steel extension spring provides a controlled restoring force, ensuring that each tip maintains firm and uniform contact with the honeycomb cell walls during the weld cycle.

This compliance is especially important in resistance welding, where even minor thermal expansion of the copper tips can affect contact quality. By allowing for slight movement while preserving alignment, the spring-loaded design ensures stable weld pressure without risking tip misalignment or over-compression. The holder also includes a puzzle-piece interface that guarantees precise tip positioning and easy reassembly after maintenance. This design was inspired by the commercial THP Tweezer Handpiece, which also relies on spring-loaded force for consistent welds. Overall, the tip holder enhances both the reliability and repeatability of the welding process under real-world conditions.

Structural Assembly:
Base, Table Top, and Stationary Tip Holder

The structural assembly of the system—composed of the base (case), table top, and stationary tip holder—provides the foundation for accurate and repeatable welds. The base houses the linear actuator and supports all moving components, ensuring controlled motion along a single axis. It includes mounting points for both the actuator and the stationary tips, as well as cutouts for wiring and maintenance access, making the system compact and serviceable.

Mounted on top of the base, the table top acts as the primary fixture for positioning the honeycomb rings. After several iterations, the final design features a wide window rather than slits, improving both visibility and freedom of movement for the electrodes. Side extensions were added to support the full ring structure, allowing welders to rest the part flat without deformation during setup.

The stationary tip holder is embedded into the base, directly opposite the spring-loaded movable tips. It holds the opposing copper tips in fixed alignment, enabling the weld to occur with precise contact from both sides of the seam. This component is designed to be modular, so stationary tips can be easily swapped or realigned as needed. Together, these structural elements provide the mechanical rigidity and geometric precision necessary for consistent multi-point welding operations.

Operation

In an effort to reduce the manual strain during the Resistance Welding process, we boiled down the entire operation to two buttons - an actuation trigger and a footpedal to fire the welding power supply. The only manual intervention required is aligning the tips inside the honeycomb cells. The sequence of operation is shown below:

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