Designing a Special for a Legacy Part

One face was right up against a raised boss, creating an interrupted cut and leaving little room to work. In the past, Tri-Tec used a similar indexable BSF tool for this type of work. The tool had a small shank that could pass through a hole and expand to cut on the far side. It was a setup that had worked for years, but the insert line was discontinued.

Even if it had still functioned, the tool’s limited diameter range wouldn’t have worked for the larger spot facing needed. In Navy work, older designs are common. Tri-Tec was working on a part that had to be kept in service, but the tooling setup for that part no longer worked. With no way to repeat the original process, the team needed a new, supported solution that could meet the same specs and remain available for future repairs.

Smith had previously worked with Heule on a job involving a silicon brass housing for fiber optic cable mounts. When the actuator housing presented this new set of challenges, he knew where to turn. Support includes engineering, an in-house test center that helps validate ideas before implementation and an extensive North American network of sales partners and distributors. Heule’s standard lines cover both front and back hole operations, and roughly half of its business comes from custom-engineered approaches tailored for unique applications.

Smith worked with Matt Clark of Clark Manufacturer’s Service LLC, Heule’s representative in Seattle, to evaluate the part’s geometry and cutting requirements. Together, they selected a Heule back spot-facing tool (BSF-A-0650/040-7.0) that could reach through the 6.53 mm hole and cut a clean 13.21 mm flat on the far side of the part.

No additional fixturing was needed to use the BSF tools. The only process change, compared to the obsolete tool, was to rough drill the through hole to match the BSF tool, then open it up to final size after the BSF tool cut the part. Heule tools feature retractable cutter mechanisms, so the blade expands inside the part and retracts after the cut is completed. This eliminates the need for custom fixturing or multiple-step setups while preserving accuracy and surface quality.

The interrupted cut path caused by the raised boss required some adjustments. Smith said the team tuned their feeds and speeds to stabilize the toolpath and complete the cuts successfully. “It proved to be problematic just because of the nature of the casting and the interruption, but once we dialed in on what we were doing there, it worked flawlessly.” Only two housings were prototyped before the part was redesigned, but Smith said the new layout may still include internal machining features.

More importantly, the success of this prototype job opened the door for future applications. Tri-Tec uses the same Heule tool setup to remanufacture other parts that were originally produced decades ago. Smith emphasized the importance of having tools that remain available and supported long after the original job is completed, even for small batches. “We may only make a few of something, but we need the tools and process to work every time.

Especially in Navy work, these parts don’t just go away. They come back in for repair, even decades later.” For shops like Tri-Tec, choosing tooling partners is about more than cycle times or unit cost. Smith said repeatability, technical support and long-term availability matter the most.

Captions: Credit: All images: Heule Tool

(100_4497.jpg) The actuator housing Tri-Tec Manufacturing was prototyping was made from C86300 manganese bronze. Inside the casting, four raised mounting pads needed to be machined to create smooth, flat surfaces to support a transformer. (Heule Back Spot Facing Tool.jpg) Heule tools feature retractable cutter mechanisms, so the blade expands inside the part and retracts after the cut is completed. Pull Quote: ‘We have more than 20,000 unique part numbers, but, oftentimes, our orders will be 10 or 15 parts. We’re almost like a job shop in that way.’