CNC?Head Porting & Machining Centers - Engine Builder Magazine

CNC?Head Porting & Machining Centers

The fact that CNC machines have come down in price over the years, coupled with less complicated interfacing systems means that today they can be used by nearly anyone. You don’t have to relearn everything. You don’t have to take endless courses on how to make a tool change. Today’s machines are sophisticated and savvy enough to take over most of the legwork and let you concentrate on what you do best.

These days, engine builders must get as much as possible out of every piece of equipment in order to make the investment make financial sense. And with the increasing complexity of performance and late-model production engines, some shops are forced to the edge of their older equipment’s capabilities. Shops looking to update older equipment have many choices today, but many engine builders have started looking for more than just an improved version of what they already have.

New CNC machines – from head porting machines to full machining centers – can automate repetitive tasks with unmatched precision and, hopefully, pave the way to future growth. To help you make sense of what’s out there, and in alphabetical order, here are details on some of the top CNC head porting machines and machining centers on the market today:


Centroid’s 5-Axis CNC Cylinder Head Porting Machine is a complete turn-key system, supplied with comprehensive CNC porting training. Centroid claims its system overcomes limitations of many other CNC porting machines with its unique and patented technology while providing its customers with expert training and support. This combination of accuracy, repeatability, training and support allows its customers to produce some of the most powerful race winning heads on the market, says a company spokesman.

Much more than just a porting machine, the Centroid A532 can machine an entire cylinder head from a raw casting. Operators can also engrave letters, numbers and logos, machine valve spring pockets, rocker arm mounting pads, drill or contour out oil drain back holes for better flow, machine push rod area for clearance, relieve pistons for valve clearance, port intake and exhaust manifolds, bore valve guide locations, create intake and exhaust plates and so on.

The Automatic Digitizing feature copies an original hand-ported head for rapid replication. The company’s DP4 Digitizer runs on the CNC machine so there’s no need for an extra digitizing machine.

Centroid’s tilting rotary table was designed specifically for CNC Cylinder head porting. Made in the USA of rigid cast iron the TRT 32-100 provides 32 degrees of tilt in each direction (64 degrees total) so the tool can cut even the most radical ports.

Centroid offers the latest Multi Axis Mastercam X3 software with a one year maintenance agreement included with the A532. The company provides instruction on how to use Mastercam to create perfect CNC ports. This powerful package opens your digitizing data and creates the program to port the head, and allows you to tweak hand-ported designs if necessary. The Centroid/Mastercam CNC porting system has several advantages, both in cost and effectiveness while at the same time is the easy to learn, says a company spokesman.

Made in the USA, the Centroid M400 comes from a long history of tough industrial CNC controls. “The Centroid CNC has been known for its user friendly operator interface combined with powerful features that produce quality cuts and finishes.” Simple setup menus guide operators through the process. Advanced CNC features such as unlimited file size with accell/decell look ahead provides smooth continuous tool motion, USB 2.0 ports and ethernet for easy file transfer, stop and restart at any point and program tool path graphics. The Centroid control is a fast PC- based CNC with updatable software so you are always using the latest technology.

Centroid’s DP-4 probe and software is specifically designed for digitizing cylinder head intake, exhaust ports and combustion chambers. This patented probe has special features just for cylinder head copying, making it simple for users to specify copy resolution for the most accurate and best results. Not only is the probe used to copy custom shapes, the same probe automatically sets the head zero locations on the fixture.


Millsite’s latest CNC machine, the Millport Super Red Rhino, incorporates a unique swivel head that rotates 45 degrees both left and right.This allows for the machining of those more aggressive port angles that weren’t previously possible.

The super Red Rhino was designed with versatility in mind, says Millsite’s John Trusty. “Our quick-change fixturing allows a rapid change from a 5-axis porting machine to a block boring and surfacing machine within minutes. It rapidly reproduces and modifies prototypes. Or just remove the head fixture and put a machinist vise in its place and begin general 3-axis machining.”

Millsite offers two methods of digitizing: the old method, consisting of using a contact probe and recording data points along a surface; and the new method, which uses a white-light scanner to capture the desired surfaces.

Millsite’s digitizing process uses 3D scanning from the old process of using a contact probe, and has drastically reduced data collection time while increasing accuracy and repeatability. The 3D scanning process digitally reconstructs and seamlessly duplicates your original hand-ground cylinder ports. This has resulted in the digitizing process, which used to take many days, now being complete in a matter of hours. The equivalent of about 4 million points are taken to achieve extreme accuracy.

The art of hand-grinding ports and getting the perfect shape, along with the desired air flow results, gets more attention to perfecting the design instead of having to do every port, while maintaining symmetry. This process of redesigning ports to eliminate flaws and maximize the volume and velocity of air can be duplicated and automated.

Included in the scanning process is the recording of a reference datum for locating the surfaces upon importing into CAD/CAM. The time spent struggling with data to accurately replicate the original surface has been drastically reduced to a matter of minutes, says Trusty. You no longer have to manually record data to create a “rough” surface to 5 axis digitize from. The 3D scanning process also eliminates issues such as: only recording center-point data, features being rounded-off by probe-tip diameter, having to offset the surface to achieve real size, and eliminates any “bad hits,” “shanking,” or “no hits.”

You don’t have to worry about the probe getting stuck in small features and tough areas. You no longer have to patch two sides together, reducing the possibility of mismatch. And best of all, your machine is free to use instead of having to wait for digitizing to finish.

Both processes begin with the hand-ground master ports. Using the probe, the next step is to use 3-axis with 4+5 positioning to record single curves at fixed locations. These curves will be used to make the rough surface. A 5 axis digitizing toolpath is created on that surface to drive the probe. The result is a collection of splines that create a wireframe for the port. Upon some manipulation of the resulting data, a cutting toolpath can then be created.

Along with 5 Axis digitizing, the probe also offers such digitizing procedures as Radial Digitize, Grid Digitize, and Contour Digitize. The probe is also very useful for doing CMM work, can be used to check locations and positions of features and is a very useful tool to measure dimensions that would be difficult or impossible to reach with standard measurement tools.


The RMC V50HP takes CNC head porting to an new level of precision and efficiency. Its simultaneous 5-axis, PC-based CNC control easily handles precision head porting.

RMC’s V50 CNC is a true simultaneous 5-axis, PC-based CNC controlled machining center equipped to handle precision head porting as well as other CNC related engine rebuilding operations. All of RMC’s CNC based machines employ simple conversational menu driven programming as well as conventional “G” coding capabilities.

The V50HP uses industry standard CNC programming language (G-code) and conversational programming as compared to other proprietary programs some suppliers use that limit machine versatility.

Features of the V50 include:

• Nikken Rotary Table: helps achieve highly accurate head positioning requirements of the many machining operations needed for truly accurate head porting. When combined with RMC’s heavy duty head holding fixture, you have the ability to create a finished head from a raw casting.

• Rapid Traverse: 1,000 ipm (25.4 mpm) traverse speed with look ahead and high speed machining memory is four times as fast as most industry models when moving from position to position which greatly increases efficiency and production rates.

• Hardware and software Integration: several software packages, to include cad/cam and digital scanning (for off line digitizing) have been integrated into the overall head porting package. Utilizing these specific packages with RMC’s hardware, fixturing and tooling insures the success of each individual piece in this complex puzzle, says the company.

• Infinitely Variable High Speed Spindle: 50 – 8000 rpm spindle speed allows the V50HP to achieve optimum finishes on a variety of materials such as cast iron, aluminum, compacted graphite and others. A 12,000 rpm spindle is optionally available.

• Cat 40 Taper Tooling: unlike competitive machines, the V50HP uses industry standard, readily available Cat 40 tooling, which makes “tooling up” for special jobs much easier.


When Rottler launched its new P69 5 axis digitizing and porting machine at PRI 2009, it replaced the venerable P55 that had been on market for 8 years. “The main difference between the two is the P69 is larger. It’s designed to accommodate longer 6-cylinder heads such as those from John Deere used for tractor pulling and 6-cylinder 24 valve heads with timing chain/belt castings on the end of the head,” says Rottler’s Anthony Usher.

The most important feature of Rottler’s porting system, says Usher, is the simplicity of the complete process from digitizing to programming to actually machining the heads. Rottler has developed and refined this system over 8 years.

“Most customers buying porting machines today do not have CNC programming knowledge and require a system that is easy and fast to learn,” says Usher. “They need to reproduce heads fast in order to be able to pay for their investment. Most operators are able to learn the system in 3 to 5 days.

Rottler utilizes Touch Screen technology to simplify machine control operation. Touch screen allows separate control panels to display only the information and control buttons that are required for that particular operation to be displayed and hide info and buttons not required at that time. Most CNC machines have large control panels with many buttons and this makes learning the machine slow and complicated – stressful to a new operator.

The CAD/CAM system allows various milling operations such as valve spring seat machining, high lift camshaft clearance, cam follow bore machining, engraving, head gasket surfacing, manifold surface milling. “So in a nutshell, the P69 is a 5 axis machine that is geared toward head porting, but can perform any operation that a standard 5 axis machine is capable of. You get the best of both worlds,” Usher says.

Standard equipment includes software to port cylinder heads only. Rottler offers a service to digitize heads and supplies a complete program to port heads. An optional digitizing system with Renishaw wireless probe and CAD/CAM software system allows the machine owner to “reverse engineer” or probe/digitize heads that have already been ported. This software allows the operator to design tool path programming ready to cut the ports and combustion chamber. Software also allows ports to be designed on a stand-alone computer then transferred to the machine to port the cylinder head.  

The Rottler F69ATC can be used to manufacture parts similar to a traditional CNC machine as well, Usher explains. It has full coolant enclosure and a 24 tool automatic tool changer (ATC).

The F69ATC offers three CNC control systems:

1) A traditional CNC operator interface control panel similar to industrial CNC machines for general machining utilizing G code. This system can import programs from third party CAD/CAM systems.

2)A Rottler CAD/CAM programming package that allows the operator to design and machine parts. This software allows advanced features for example digitize a work piece to copy it. This software could bee used to create a program to profile an engine block for block lightening.

3) The Rottler Engine Machining Program (REMP). This conversational software system has been in use for more than 25 years especially for engine block and head machining. This system is well known in the engine building world for ease of use when compared to straight CNC-controlled machines.
New CNC machines 
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