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High-Density 4th-Axis Machining with Stallion Tombstone Trunnions and 5th Axis RockLock
- May 13
- 4 min read
One of the biggest advantages of 4th-axis machining is the ability to do more work in fewer setups. But the real value comes when the entire process is built around fixture density, repeatability, rigidity, and flexibility.
That is exactly what makes a setup like this so powerful.
This Stallion Tombstone Trunnion is being installed in a Haas Automation VF-7 with an HRT310 rotary table. The customer is using the 52mm RockLock system from 5th Axis Workholding to mount custom fixtures across multiple faces of the trunnion. In this case, the setup is designed to run 20 fixtures at a time, with 5 fixtures mounted on each face.
For a vertical machining center, that kind of fixture density can completely change how the machine is used.
Instead of loading one or two parts at a time, the operator can load a full batch of parts, index from face to face, and keep the spindle cutting for a much longer period of time. That means fewer interruptions, fewer door openings, less handling, and more consistent production.
Turning a VMC into a High-Volume Production Cell
A standard VMC is often limited by how much work can be staged inside the machine at one time. Even with a rotary table, the workholding strategy determines how productive the machine can actually be.
A Stallion Tombstone Trunnion helps solve that problem by creating multiple usable workholding faces around the rotary axis. When paired with the right fixture system, each face becomes valuable machining real estate.
In this application, the customer is using 5th Axis RockLock to mount custom fixtures directly to the trunnion. With 20 fixtures loaded at once, the machine can process a larger batch of parts per cycle while still maintaining the accessibility and flexibility of a VMC.
That creates several key advantages:
More parts per setup
Less operator intervention
Longer spindle-on time
Better machine utilization
More consistent part flow
Faster changeovers between jobs
This is where a trunnion system becomes more than just an accessory. It becomes the foundation for a repeatable production process.
Why RockLock Adds Flexibility
High volume is important, but flexibility matters just as much.
That is where the 52mm RockLock system from 5th Axis Workholding adds a major advantage. RockLock allows the customer to mount and remove custom fixtures quickly while maintaining repeatable location. Instead of dedicating the entire trunnion to one permanent fixture design, the customer can build a flexible platform that supports different part families, different fixture plates, and future process changes.
That matters because production needs are rarely static.
A shop may need to run one part today, a similar family of parts next week, and a completely different job next month. With a modular quick-change system like RockLock, the trunnion can adapt without starting from scratch every time.
Custom fixtures can be built around the RockLock interface, loaded onto the trunnion, and swapped as production requirements change. That gives the customer the best of both worlds: high fixture density for production and modular flexibility for changing work.
Combining Custom Fixtures with Modular Workholding
The strength of this setup is not just the trunnion or the RockLock system by itself. It is the way the two work together.
The Stallion Tombstone Trunnion provides a rigid, multi-face platform for 4th-axis machining. The RockLock system provides a repeatable interface for locating and clamping custom fixtures. The custom fixtures are then designed around the actual parts being produced.
That combination allows the customer to build a process tailored to their production needs without locking themselves into a single-purpose setup.
For demonstration purposes, this trunnion was shown with several vise and jaw combinations, including 5th Axis vises, SCHUNK KSC3 vises, custom jaws, serrated jaws, 3D printed jaws, and dovetail-style fixturing. But the real production value comes from the customer’s custom fixtures mounted across the trunnion faces.
That is an important distinction.
The trunnion creates the platform. RockLock creates the modular interface. The fixtures create the process.
When all three are designed together, the result is a much more capable VMC.
Why Braking Power Matters in 4th-Axis Machining
This package also includes our new TS1200-IB braking system, which adds serious holding power to the outboard side of the trunnion.
As trunnions get longer, heavier, and more densely loaded with fixtures and parts, braking torque becomes more important. A rotary table brake alone may not always provide enough holding power for aggressive cuts, off-center loads, or heavier 4th-axis machining. That is especially true when the workholding is spread across multiple faces and the cutting forces are acting away from the rotary centerline.
The TS1200-IB is designed to help keep the entire system rigid during machining. It works alongside the rotary table brake to add clamping support at the outboard end of the trunnion.
The result is a more stable setup, especially when the customer is pushing heavier cuts or machining with more fixture mass on the trunnion.
For high-density 4th-axis work, rigidity is not optional. If the trunnion can move, vibrate, or deflect during machining, part quality and tool life suffer. Braking power helps protect the accuracy and consistency of the entire process.
It Is Not Just a Rotary Table — It Is a Complete Process
This is what makes trunnion workholding so interesting.
The value is not just in adding a rotary table to a vertical machining center. The real value comes from building a complete machining process around the machine, the rotary table, the trunnion, the brake, the workholding, and the parts being made.
Each component has a job.
The Haas VF-7 provides the machining envelope. The HRT310 provides the rotary motion. The Stallion Tombstone Trunnion creates multi-face fixture capacity. The 5th Axis RockLock system provides modular, repeatable fixture mounting. The custom fixtures hold the actual parts. The TS1200-IB braking system adds the holding power needed to keep the setup rigid.
When those pieces are designed to work together, a VMC can become a much more productive machine.
Instead of treating the 4th axis as an occasional add-on, the customer is building a production system around it. That is where the return on investment starts to become very clear.
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