From Block Work to Manufacturing - CNC Machines Wear Many Hats - Engine Builder Magazine

From Block Work to Manufacturing – CNC Machines Wear Many Hats

From a shop owner’s perspective, a good employee is one who’s never late, is extremely productive and never asks for a raise.

Enter the perfect employee: the multi-purpose computer numeric controlled (CNC) machine center can do the work of several employees and never complain about it.

There is no doubt that today’s machine shops must be leaner and meaner in order to survive, and many shops are doing more than just surviving by utilizing CNC machines to their maximum capability.

Engine builders must get as much as possible out of every piece of equipment in order to reap the maximum return on their investment (ROI). Performance engines and late-model production engines have much tighter tolerances and complexity these days to the point where some shops are forced to the edge of their older equipment’s capabilities. Shops looking to update older equipment have many choices for machine tools, but some engine builders are looking for more than just an improved version of what they already have. This time, many are looking to CNC machine centers to automate repetitive tasks and hopefully pave the way to future growth in some manufacturing capacity.

“I think it opens up a whole new door in general,” says RMC Machine’s Matt Meyer. “The latest PRI Show showed that people are a lot more interested now. In the first year that we showed our CNC machine at PRI, people were interested in its manufacturing capabilities but then it died down a little until last year. I think a lot of shops are now looking to replace outdated machinery, so they’re looking at all the options. If you consider the costs to add a boring bar, surfacer and a few pieces of tooling, you’re up there around same price as a CNC machine. And then you look at the capabilities of a CNC and you can do not only the traditional block work but experience almost endless possibilities besides that.”

Requiring fewer employees and less floor space is a good thing, says RMC’s Ray Meyer. “You can run much leaner. A lot of people we talk to are still using machine tools from the mid to late ’60s. But they’re realizing the customer’s demand for greater accuracy and the many operations done to an engine block today require a CNC machine.”

Says Rottler’s Ed Kiebler, “Many shops using this equipment reap huge time savings benefits. What normally takes a shop two to three hours to line bore will take 45 minutes to one hour in our CNC machine. The machine offers three ways of locating cylinder bores and lifter bores (blueprint, indicated or probed).”

Industry experts tell us that not only are shops looking for equipment to handle traditional engine block work but also to open up possibilities for manufacturing and development projects that would have been unheard a few years ago.

“We’ve seen shops use these machines for manufacturing many components, from very simplistic all the way to more complex pieces like stator rotors in the transmission, which is almost aerospace level,” says Millport Machine’s John Trusty. “We’ve seen people use them to make all sorts of automotive components.”

Another factor helping to ease the conversion to CNC for some engine builders is that the majority of automotive CNC machine centers (which are multi-purpose CNC machines made specifically for engine work) offer nearly turnkey programming. There’s no need to spend evenings and weekends in a classroom trying to learn G-code, the prevalent programming language, in order to carry out traditional engine block machining.

G-code is a term that has been around the industry for many years and is supposed to be standardized in the industry, but it’s not, explains Millport’s Trusty. “Most of your CAD/CAM systems output G-code, so it’s the universal language between machines. But some manufacturers have leading zeros and some do not. For instance some may specify G1 and some say G01, so there’s a differentiation between the G-codes that are available for various manufacturers.”

Trusty says that his company and other manufactures create essentially a programming language with a user interface layer that outputs G-code for you. Every manufacturer does it a bit differently but the goal is the same: create an easy-to-use interface between the user and G-code output.

Manufacturers of this equipment have done the homework for you by creating easy conversational programs that insert the necessary information for you to machine any engine you’re working on. Experts say that learning how to do block work can be done in as little as an hour by even the most inexperienced shop hands. Therefore, the urgency for skilled machinists, though still a need, may be greatly reduced.

Traditional Block & Head Work

The main advantage to pre-programmed, conversational CNC machines is that once the data has been properly entered into the machine it can perform the task virtually unattended. Repetitive operations can be streamlined and multi-step, complex tasks can be done more easily.

“Engine builders are primarily looking for CNC machine centers for block work,” says Millport’s Trusty. “They want a machine to bore cylinders, deck the tops and realign lifter bores and possibly clearance blocks for strokers, among other things. We also have customers using them for block lightening. One customer, for example, digitized an entire cylinder block and was able to knock off 35 pounds in excess weight.”

For traditional engine block work nothing is faster or more flexible than a CNC machining center says Sunnen’s Tim Meara. “I’ve been working with the full CNC machine centers for about four years. The amount of work you can get through and the capabilities that these machines have is simply incredible. It’s especially apparent if you’re doing a lot of machining operations on separate machines. And the accuracy of the results you get with these machines is astonishing. Take, for example, putting a set of splayed caps on a block.

If you were to set it up on separate machines you’d have a couple of hours involved in the process – but it takes a CNC machine 6 minutes to complete. Those are big time savers.”
Rottler’s Kiebler agrees: “The big savings are in setup time and labor time. Depending on how you tool your CNC machine, you can automatically bore all 8 cylinders by pushing a button one time. CNC machine centers can bore cylinders, lifter bores, line bores and cam bores. The machine will deck surfaces, front and back of engine blocks. It can drill, tap, counterbore, and relieve cylinders at the bottom for easier honing and so much more.”
One of the most popular uses for these machines appears to be for blueprinting engines. In reality, you can’t blueprint a block on any other type of machine than a CNC machining center according to experts.

“What everyone used to consider blueprinting an entire engine was blueprinting a few specific parameters like the deck heights or center lines bore to bore. You could never blueprint the entire block to itself,” says RMC’s Ray Meyer.

“Any time you have to take a fixture off and relocate it, you lose accuracy. You’ve lost a data point,” agrees Matt Meyer. “So with our machine, we pick up one data point and you can machine 90 percent of the block without changing that data point.”

Yet for all their timesaving promises, many experts agree that some engine builders are unnecessarily a bit intimidated by CNC technology. They may think that CNC machines are overwhelmingly difficult to learn but that’s just not true. “It’s really simple to do the basic operations that we do in the automotive machining industry,” says Meara. “I think a lot of people make it out to be a lot more difficult than it really is.”

Manufacturing Capability

If you look around nearly any manufacturing company today chances are you’ll see a CNC machine center. Almost anything made out of metal or plastic can be made in a CNC machine center. You can build engines one day and aerospace parts the next. The capabilities are limitless. These machines have, in essence, become today’s mini-manufacturing centers.

In addition to standard block and head preparations, Millport’s Trusty says engine builders are using these machines for manufacturing parts and components. In fact, experts say engine builders are making hundreds of parts out of billet today. Everything from handlebar risers for motorcycles to adaptor plates for carburetors to wheel hubs, alternator brackets and so on are being produced in small machine shops across the country.

Makino’s Mark Rentschler says his company has provided manufacturing solutions for more than 20 years to some of the biggest manufacturers in the world. “To the production environment Makino offers turnkey solutions, which are virtually automated from beginning to end. The sky really is the limit to what you can do with a CNC machine center, and when you add robotics and pallet loaders it is 21st century as we imagined it to be,” he explains.

Sunnen’s Meara says that he has some engine builder customers who have gone into manufacturing components, in many cases simply to make parts they can’t get for their own use. “One guy we’ve worked with is making his own 4-bolt main caps for a Ford because he can’t get them anywhere. It was his idea and he machines the whole thing.”


CNC controls are available on many types of machine tools and many engine builders already have practical experience with them. For the most part if you’re doing traditional engine work, most machine tool suppliers offer solutions for basic operations that are very simple.

However, for more complicated programs or to make your own parts, there is definitely a learning curve. Experts point out that you can’t learn G-code in an hour and you can’t learn CAD/CAM programs without a lot of training. But one supplier insists that you can start making money right away doing traditional engine work and work your way up slowly to manufacturing parts. That way you have the capability and you can start using the machine right away.

“We have canned cycles for drilling, square pockets, round pockets, threading, where you just push a button and it’ll ask you questions, says Millport’s Trusty. “It is a G-code machine, but for many of the basic operations you don’t need to know G-code.”


One of the intriguing features of CNC machine centers is the ability to probe and digitize parts and measurements. Today’s CNC machines offer the ability to take a part and touch off on key points and enter the data points into the computer to reproduce on another component.
Many CNC machines use a stylus probe to measure deck heights, bore centers, etc., automatically. There are some simple programs that you can call up and modify however you may want. For instance you can take a basic one-cylinder engine program and add any number of additional cylinders you want to duplicate that one cylinder. Also, with the digitizing feature you can machine engines that are not pre-packaged with the software.
You have a choice to either bore the same as on the blueprint or measure it on a probe and use those dimensions.

You may have an engine that will take .060? to clean up because it’s so far off from original manufacturer specs – but maybe it might clean up within .020? if you take it from a probe position. This flexibility can help you salvage components that may be otherwise be difficult or impossible to use. Do you have employees that are this flexible?

Retrofitting Older Equipment with Modern CNC Controls

For some engine builders who can’t yet justify getting rid of their old manual or numeric control (NC) machines, a CNC retrofit may just fit the bill and your budget.

There are several retrofit CNC controls manufacturers on the market. We recently spoke with Centroid, Howard, PA, about its retrofitting options.

Centroid’s Keith McCulloch says there are many brands of older high quality used machines available for reasonable prices today, and many shops are still using some of this equipment. However, in many cases, the original controls have gone past their useful life and the machines themselves have outlived the electronics.

“Often, older NC and CNC machines can be found in excellent mechanical condition,” says McCulloch. “These machines usually have been a nightmare to operate and maintain since the stock control is so outdated. Also, since many of these old controls were never really that good to begin with, and the original systems were so difficult and problematic to use it is common to see early NC machines with low hours on them. This makes them prime for a retrofit.”

Bridgeport manufactured a large number of “Boss” machines throughout the ’70s and ’80s. McCulloch says these make an excellent choice for a CNC retrofit.

McCulloch says the first step is removing the old NC control from the machine. With a Boss machine this only takes about 30 to 45 minutes. The old Boss 5 control has two cabinets, one on the right and one in the back of the machine. Both are removed, reducing the footprint of the machine significantly. The Boss used big, old, hot and noisy stepper motors, which are replaced with new DC servomotors. The Centroid servomotor is more than twice as powerful and twice as fast as the old stepper motor it replaces. It has a resolution that is over 8 times that of the old motor, and the new motor is closed loop, unlike the old stepper motor, so it never loses position.

With its new CNC retrofit kit with new motors and all new control electronics, the Boss can be a more capable, reliable and user-friendly machine. It is compatible with modern computer equipment and programs, and the software can be updated, unlike the old control. With this retrofit, McCulloch says a shop can achieve 3-axis machining with high speed processing; two-dimensional and three-dimensional digitizing; stop and restart job at any point; remember part zero positions if power is removed or E-stop; remember part programs and tool libraries; and automatic tool height measurement.

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