When a customer brought us a new 13.6-liter diesel engine design for high-horsepower agricultural and construction equipment, they didn’t just need a machining vendor — they needed a partner who could help them bring it to the finish line. This was a critical engine platform, and at the heart of it was a complex ladder frame housing.
From the start, the customer knew this part wouldn’t be easy to machine. It measured over 40 inches in length, required tight tolerances and precise torque specs, and would eventually be assembled using robotic torquing to ensure consistency. They came to Stecker because of our reputation, not just for machining complex parts, but for our expert engineering staff who could help them perfect the design.
As with many of our projects, the final machining is only a small part of the story.
Ladder Frame Project Description
This OEM’s ladder frame design sits on top of a large, 684-horsepower diesel engine block and plays several essential roles. It holds the valve train’s key components — valve springs, camshaft, and rocker shaft — and distributes the engine’s internal loads. Structurally, it provides rigidity, reduces vibration, and ensures proper alignment of the shafts that drive and synchronize valve movement.
Prototyping, Partnership & Engineering on the Fly
The customer brought in initial blueprints of their engine design and asked if we’d help turn it into a machined reality. It wasn’t just about quoting a part, but rolling up our sleeves and working side-by-side with their design engineers to problem-solve from the ground up.
Their design teams met onsite at Stecker to collaborate on prototype development with our engineers. We began with aluminum sand castings, which are ideal for prototyping due to their lower tooling costs and quick turnaround.
The ladder frame required extremely tight torque and dimensional tolerances within a few microns, which meant the part had to be machined exactly as it would be used on the engine. Working with the customer’s design team, we made real-time design adjustments during machining to refine features and optimize bolt placement.
Because aluminum castings can twist or flex under torque, it was essential to maintain identical torque specifications during testing. We even used the same bolts and torque values during line boring. We also built a simulator that mirrored their assembly setup, allowing us to validate the machining process under real-world conditions. To guarantee repeatability, we integrated robotic torquing, ensuring every part met the exact same assembly standards as those on the production line.
That level of detail mattered. With a part this size and this structurally important, even slight deviations could throw off the entire valve train system. By building a simulator and mimicking the OEM’s assembly conditions, we helped ensure it would install cleanly, perform consistently, and meet the customer’s rigorous demands.
Engineering & Machining Challenges
What made this project particularly challenging was the shift from sand casting to die casting as the program ramped toward production volumes. Die casting offers efficiency and repeatability, but it also introduces risks like porosity — tiny voids in the material that compromise strength and surface integrity.
Compounding the issue was the fact that die castings can’t carry excess machine stock. Removing too much material during machining can actually create porosity, not eliminate it. That meant we had to walk a fine line — just enough material to machine clean surfaces, but not enough to trigger casting flaws.
To solve it, we partnered closely with the foundry, holding joint reviews both at our facility and onsite with their team. Together, we tested different casting allowances, adjusted machining strategies, and ultimately modified the tooling over a dozen times to get it just right.
Going the Extra Mile for Quality & Traceability
Transitioning from prototype to full production required a significant investment in custom tooling to maintain tolerances and consistency across thousands of parts. Because this ladder frame is machined on a dedicated line, every fixture, clamp, and workflow was purpose-built for this part alone. We spent extensive time up front on Poka-yoke processes, ergonomic testing, and operator feedback to ensure the cell was dialed in before ramping up.
From a quality standpoint, this project leaves nothing to chance. Every single ladder frame is 100% inspected, and each one is serialized with a data matrix code that links directly to its inspection report. Our system logs all dimensional data digitally, so if a customer calls with a question, whether tomorrow or five years from now, we can pull up that exact part’s inspection history in seconds. That level of traceability is essential for a part this critical, and it gives our customer complete confidence that every component leaving Stecker meets spec and is fully backed by data.
Built for the Toughest Jobs & Ready for New Challenges
In my 24 years at Stecker, I can confidently say this is one of the toughest parts we’ve ever built. It demanded every ounce of engineering expertise, foundry coordination, and process discipline we had. And that’s exactly the kind of challenge we’re built for.
Complex parts like this aren’t just technical challenges, they’re opportunities to collaborate, innovate, and prove why Stecker is the vendor-partner of choice when precision and performance can’t be compromised.
With recent equipment investments and capacity improvements, we’re ready to take on new high-complexity machining projects for OEM partners. Contact us to talk through your challenging CNC machining project today.
