From Manual Mills to Hybrid CNC: How Conversational Control Transformed Toolroom Machining | Modern Machine Shop

When a veteran machinist refused to use a new CNC mill, his resistance sparked a revolution. This article traces how Southwestern Industries developed ProtoTRAK — an intuitive hybrid control system that remains vital as AI begins reshaping manufacturing.

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Steve Pinto on the shop floor of Southwestern Industries’ headquarters in Rancho Dominguez, California. Pinto is standing beside a TRAK TC820LTYsi, a versatile turning center that’s been modified to include VersaBuilt automation integrated with a Universal Robots cobot arm for machine tending. This setup mirrors ProtoTRAK’s own evolution, blending Siemens’ SINUMERIK ONE touchscreen simplicity with multi-axis machining capabilities. Source (all photos: Southwestern Industries.

It was the early 1980s, and Richard Leonhard, then-owner of Southwestern Industries in Culver City, California, was looking through his office window down onto the shop floor below. He had trained his eyes on a machinist named Claude, a veteran of manual mills, as Claude deliberately walked around the shop’s brand-new CNC mill to reach the old, familiar Bridgeport.

It was an open act of shopfloor rebellion.

“Damn it, Claude!” Leonhard fumed under his breath. “You wouldn’t use a CNC unless you could stand there and tell it what to do, move by move!”

Years later, Leonhard and his team would look back on this moment as the spark behind ProtoTRAK, a control system that catered to the Claudes of the world and reconciled the differences between CNC precision and old-school machinists’ intuition.

I recently visited the headquarters of Southwestern Industries for an in-depth conversation and facility tour with Steve Pinto, who joined the company in the early 1980s and now serves as its third president and CEO. As artificial intelligence (AI) becomes more embedded into metalworking production, understanding how one company used anti-tech defiance to drive innovation may prove critical in the face of what’s coming.

A display cabinet showcases eight iterations of the ProtoTRAK control, tracing its evolution since debuting in 1986. Each unit reflects advancements in conversational control, from early models to modern interfaces.

By the mid-1980s, computer numerical control (CNC) had already transformed production machining across much of the world. CNC was automated and repeatable, and its high-speed capabilities were slashing costs and increasing consistency for big OEMS and suppliers across multiple industries. Yet, the toolrooms of many manufacturers — the place where prototypes, fixtures and short runs still dominated — largely remained stuck in the manual age.

At that time, toolrooms were places that demanded flexibility that CNC didn’t offer. Manual machines were a natural fit for jobs that arrived as sketches or concepts. A journeyman machinist might make a dozen decisions during a cut, use trigonometry to calculate arcs, or tweak depths and angles based on feel. This was high-skill work, as recognized by a 1993 article published by Modern Machine Shop about the early ProtoTRAK: “Journeymen machinists… are among the highest paid workers in manufacturing,” the article stated. For Claude and those like him, G code broke the rhythm of hands-on machining. The resistance to CNC was grounded in a meaningful workflow challenge.

That same 1993 article introduced the term "prototype controls," and framed the toolroom standoff this way: "Allocation dilemmas arise at the boundaries of manual, CNC, and automatic technologies."

Toolrooms were borderlands between old and new.

Founded in the 1950s as an aerospace machine shop, Southwestern Industries (SWI) has a history of solving shopfloor challenges. In 1963 it introduced the Trav-A-Dial, a transformative mechanical distance-measuring device that simplified in-process measurements and became ubiquitous on shop floors before digital readouts (DROs) took over.

By the early ’80s, the company had evolved into a DRO manufacturer focused on its TRAK DRO line. But Leonhard’s epiphany after the “Claude incident” had demanded a new solution entirely. Leonard wanted a control system that brought CNC capabilities to manual machines without alienating machinists.

The TRAK DPM RX5 bed mill featuring a ProtoTRAK RMX control for precise conversational programming, as seen on SWI’s shop floor. This machine exemplifies the blending of manual skill with CNC automation to support high-mix, low-volume toolroom machining.

The breakthrough was conversational control. The first ProtoTRAK was released in 1986 under the internal name "TRAK Go To," a unique concept for a two-axis CNC that eliminated Z-axis automation. It mimicked manual workflows while adding CNC precision, allowing machinists to operate in plain English. Rather than writing code, users entered prompts and dimensions. The Z-axis remained manual, providing a feeling of familiarity to journeymen machinists. As Leonhard described it, “You could stand there and tell it what to do, one move at a time.”

ProtoTRAK’s conversational control was radical simplicity in the face of fast-evolving CNC technology, an “English-language-based, prompted programming format… that requires little or no memorization of codes,” as the old MMS article explains. Features like linear and circular interpolation, canned cycles for pockets and bolt holes, and cutter radius compensation delivered CNC capabilities without the complexity. Seamlessly switching between manual and CNC modes (its “interactability” feature) supported iterative machining for parts with incomplete drawings, a common toolroom dilemma. “The machinist may position the table by hand, then… command the control to mill an arc,” the article notes.

Older ProtoTRAK LX2 and LX3 controls and related assemblies are displayed on a workbench at TRAK headquarters, where repair and refurbishing of legacy systems continue.

The final differentiator was that ProtoTRAK was affordable, priced between $8,000 and $13,500 (about $21,000 to $36,000 in today’s dollars). By 1993, more than 4,000 units were installed across the U.S., from job shops to toolrooms at General Motors, Kodak and Hewlett-Packard. The system’s ability to boost productivity over manual machines from eight to 20 times for mills and lathes won converts. John Arroues, former owner of Trio Tool and Die, saw his shop thrive after retrofitting 16 Bridgeport mills with ProtoTRAK. “It significantly enhanced competitiveness without requiring additional staff,” Arroues says.

But like most new technologies, adoption wasn’t immediate. Early CNC systems had created a league of skeptics in the industry, and ProtoTRAK would have to earn their trust. The plan was to do just that, one demonstration at a time.

Nigel Atherton, founder of XYZ Machine Tools in the UK (which Southwestern Industries would later acquire), remembers his first experience with ProtoTRAK in the early 1990s: “I knew Anilam. I knew FANUC. I knew Fagor, Heidenhain. And that ProtoTRAK demonstration was by far the simplest I’ve ever seen. I bought four systems right then.”

By the early 1990s, more than 4,000 systems had been installed across toolrooms, job shops, R&D labs and large OEMs. As the only tech of its kind, this hybrid machine had become its own category. Bridgeport took note, partnering with SWI to produce an OEM-labeled version called EZ TRAK. Fast forward to today, and ProtoTRAK is no longer just a retrofit-- it’s a standalone platform. TRAK Machine Tools, which is the brand name for SWI’s machine tool division, now manufactures a full line of machines purpose-built around the control, from knee mills to Toolroom Machining Centers (TMCs). Nearly all these machines are designed for high-mix, low-volume environments.

A TRAK technician assembles printed circuit boards at SWI’s headquarters, showcasing the company’s focus on in-house production, including electronics.

During our tour, the company’s vertical integration became evident, with TRAK now manufacturing cable assemblies, PCBs and mechanical systems in-house. “We benefit from access to high-end engineering here in Southern California,” Pinto says, “and of course the thriving electronics manufacturing environment.” While TRAK’s machine castings come from Taiwan, the rest of its machine components are manufactured in the United States.

The RMX and RLX control lines now include touchscreen interfaces and Parasolid — a 3D geometric modeling kernel developed by Siemens that allows machinists to generate tool paths directly from CAD models. They also offer DXF file compatibility, probing integration and real-time simulation. “TRAKing” mode serves to harmonize the manual/CNC processes by letting machinists step through programs with handwheels.

In the face of digital shopfloor takeovers, ProtoTRAK’s integration of manual processes remains vital on production floors across the U.S., from small job shops to Fortune 100 toolrooms. (“Every Elon Musk company is on our customer list,” Pinto says.) Utilities like LA Water and Power use it for on-site maintenance. Automotive OEMs use it for repair work. Going back, James Dyson’s early vacuum cleaner prototypes were developed with ProtoTRAK.

TRAK's shop floor displays a dense array of CNC machines and setups — the technical infrastructure for modern TRAK systems. In other areas of the facility, cable assemblies, PCBs and mechanical systems are manufactured in-house.

Today, as artificial intelligence is beginning to redefine how manufacturers quote, schedule and program jobs, harmonizing technology with simplicity remains the foundational value of ProtoTRAK. Born from a seemingly casual act of anti-tech defiance, the system has always offered an alternative to the complexity of conventional CNC. It is a control that meets machinists where they are.

Now, Pinto’s team at TRAK Machine Tools is working to extend that philosophy further. The company is investing in a new generation of features designed to support connected, adaptive and more autonomous shops. These features center around four core principles: connectivity, integration, AI assistance and workforce support:

What began as one machinist’s refusal to adapt to automation became the blueprint for a hybrid future. And it is not lost on Pinto or TRAK that shops must adapt again as AI enters the shop floor.

It’s important to remember that Claude didn’t reject technology entirely. He rejected the kind that ignored his judgment and interrupted his workflow. ProtoTRAK succeeded because it met him — and those like him — halfway. It empowered machinists by allowing them to maintain a certain level of control while gaining digital precision. It made CNC not just accessible, but incremental and conversational. And it did so long before the rest of the industry realized that simplicity is not a concession, but a strategy.

“I believe that the complexity that is coming at people is really starting to limit their ability to just do the job that’s in front of them,” Pinto tells me. “We have to provide the technology but not get in the way of the person.” That strategy remains: Listen to machinists and evolve in parallel with them. The rebellion that began with a refusal to use CNC didn’t end in defiance. It ended in a transformation strategy that still has something to teach us.

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