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If you opt for a “universal” CNC machine, you’ll need extensive training to learn the computer “coding” language required to create programs. However, if you choose a CNC machine that was designed specifically for use by engine builders, operation and the overall learning curve is much simplified, since programs for popular blocks are already included in the software. Manufacturers such as Sunnen/RMC, Peterson Machine and Rottler offer machining centers that are designed first and foremost for the guy who needs to machine an engine block. Depending on the manufacturer, they also offer either upgrades that allow cylinder head CNC porting or even dedicated machines for head work.
However, that doesn’t mean that you can’t cut anything else on the same machine. With a bit of effort on the operator’s part, you can learn to fabricate darned near any chunk of metal into whatever shape you want.
For purposes of this brief article, we’ll stick to block work. Once the block is positioned in the machine, a digital probe “reads” the block, with regard to block location on the machine, existing cylinder bore centers, existing lifter bore centers, deck height, etc. If you so choose, you can work from these existing centers and perform a cleanup (overboring cylinders, overboring lifter bores to accept liners, etc.). If your intent is to “accurize” or “blueprint” the block, you simply follow the prompts on the control screen to use an existing program that compares the block’s current dimensional status to the “blueprint” specs, in terms of correct bore centerlines. Follow the screen, hit a few buttons, and away you go.
Of course, I’m simplifying the process, but the point is that it’s not as daunting a task as you might first think. The equipment manufacturers in our industry have gone to great lengths to make these machining centers as user-friendly as possible.
You can get into trouble if and when you begin to create your own programs. Remember: the machine is controlled by a computer, which means that it’s going to do whatever the program tells it to do. If you write a program and accidentally place a decimal point in the wrong spot, let’s say you intend to type 0.010″, but you accidentally type 1.00″, the cutter is going to dive in and whack a depth of one inch instead of ten thousandths of an inch.
How much time do typical operations require? According to Rottler’s Ed Keebler, a typical cylinder boring job (simply resizing eight existing holes) takes about 12 to 15 minutes for a V8 block, depending on material removed and type of block. For correcting bore centerlines, a V8 block would require about 20 minutes (this includes the 2 to 3 minutes it takes to enter the data, plus machining time). To correct lifter bore centerlines requires about 15 to 20 minutes, after the cylinder boring has been completed. Ed noted that the entire job of correcting cylinder bores and lifter bores in a typical Chevy V8 block would require a total of about 45 minutes.
Keebler said, “You do not need any type of programming skill or knowledge. Frankly, if you already understand how to bore a block or surface a block (on traditional equipment), you can operate this piece of equipment.”
Noted RMC’s Meyer, “CNC means you have a control that enables G-code and N- code programming. Most industry standard machines will accept G-code and N-code.
Some machines, however, feature proprietary programming instead of using an industry standard.
“RMC designed their systems as turnkey systems specifically for the engine builder, so you don’t need to be a ‘CNC guy’ to run the machine.
“By the same token, once the customer realizes that he can accomplish block work doing more blocks in less time, he can begin to get into CNC machining a bit deeper, with the ability to create other parts too. About 50% of our customers are using their CNC machine for performing more tasks than only engine blocks.”
On some machines, the digital probe is automated for popular engine blocks. The probe runs over the deck, bores, lifter bores, crank, and cam centerline, etc., to compare that particular block to its theoretical blueprint specifications.
Some machines also offer universal programming, allowing you to place any engine block on the table to read the block’s bore size, bore center, number of bores, deck height, etc. The machine then measures the block and tells you what you’re dealing with.
Ideally, any CNC machine should be positioned in a decent environment, away from extreme cold or extreme humidity. For most larger machines, the shop floor requires a minimum thickness of 4 inches.
WHAT BLOCK WORK CAN YOU PERFORM?
That’s only limited by your imagination. Given the proper program, you can surface decks, bore holes to size and center, chamfer holes or edges, create O-ring grooves, machine for splayed caps, clearance for stroker cranks and rods, shell mill, lighten a block, engrave your shop’s name on the block, correct the block to blueprint specs, etc. Basically the machining center will handle everything except washing, crack checking, honing, and short or longblock assembly.
Yes, these machining centers are expensive. But, when you consider that once you have a block CNC machine, you don’t need a separate surfacing machine, boring stand, drill press, etc., you begin to realize how much floor space (and machine inventory) you can save.
In Rottler’s F60 series, for example, all operations such as cylinder boring, lifter boring, surfacing, line boring, cam tunnel boring, stroker clearancing, etc., are already written in the programming-the operator simply inputs the desired dimensions for the particular block at hand. Once those dimensions are stored, they can be recalled for another duplicate job.
To “make” a part from billet stock, according to Meyer at RMC, “The machine has conversational programming, which is all menu driven. When you start, you tell the machine what you want to do (drill holes or slots, etc.). The machine then asks you what size hole or slot you want, what the radius is, what depth, what speed you want to run, etc. You don’t need to be a computer programmer to do this. Or, you can purchase a MasterCam software package to create your own programs. If you want to save the programs that you create on your own computer, you can transfer the data to the CNC machine via a 3.5″ floppy disc or a small memory stick/flash card.”
BLUEPRINTING
According to Rottler’s Ed Keebler, a blueprint tab or button allows the operator to machine a block to blueprint specifications once the specs are entered for a particular block the first time.
Using the Sunnen/RMC V40 machine as one example, the machine provides simultaneous 4-axis PC-based CNC-controlled blueprinting for extreme precision when equipped with the 360-degree rotating head and digital probe. The true blueprinting fixture maintains exact camshaft to crankshaft relationship for precise alignment of all machined surfaces. The V40 locates from one set of initial reference points, eliminating multiple reference points that have no relationships, which improves accuracy and speeds work time. In a nutshell, blueprinting programs are already provided (either on the machine’s computer or able to be input from a purchased software program).
MACHINE COST
According to RMC, a typically outfitted V20 goes for about $67,000, while a typically outfitted V30 sells for about $95,000, and a typically outfitted V40 machining center will set you back about $110,000 to $115,000. Although this may sound like a big chunk of change (and of course, it is), you should consider that buying individual machines for dedicated tasks (surfacer, boring machine, a Bridgeport type machine, special block indexing fixtures, etc.), you’re looking at about the same cost as one CNC unit. And, when given that the CNC will produce more jobs in less time, and can be operated by a single worker, the production rate, ability to produce more cash flow, and the ability to place other shop personnel onto other jobs, the cost benefits become pretty darned attractive.
Want an analogy? Imagine a guy who fishes for a living. If he purchases a bass boat, a flat bottom boat, a V-hull boat, a canoe, a lobster boat and a commercial trawler, he can catch the entire variety of fresh and saltwater seafood that he wants. If, however, for the same money, he can buy one boat to handle all of his needs, can catch more fish in a shorter period of time and can drive the boat with no crew (since the boat’s automated, he saves on labor as well), wouldn’t it make sense to simply buy the “CNC boat” instead? Sorry…it’s the first analogy I could think of. What can I say? I like to fish.
Control panels vary in design between manufacturers (some use computer keyboards, some use button control, and some feature touch screens), but you’ll be able to call up and use existing programs as well as able to input specific dimensions.
A side view of a multiple tool holder. Depending on the level of machine, tools may be changed manually or changed automatically.
Some units will feature a tool storage rack for manual tool selection.
Here a block lightening cut has been started. Block lightening programs will either already know the block profile, or you can use the digital probe to “map” the block sides. After that it’s just a matter of telling the machine how much material needs to be removed. (courtesy Sunnen/RMC)
Here a digital probe begins to plot the block location.
As the probe measures deck surfaces (seen here), it enables the machine to know exactly where the block has been positioned on the bed.
Existing crankshaft centerline is measured as the probe touches the main bore support shaft in several spots, calculating centerline automatically.
Lifter bores can be precisely and quickly bored for repairs or to correct lifter bore centerline to blueprint specifications.
The probe touches several points in the cylinder bore to determine bore center. If you’re using a blueprinting program, this enables the computer to tell you how (and where) the bore(s) deviate from the blueprint specification.
Here a probe determines camshaft centerline. The computer references this to crankshaft centerline.
The machine calculates correct lifter bore location and centerline relative to crank and cam centerlines with no time-consuming manual measuring.
(photo courtesy Sunnen/RMC)
The digital probe is extremely sensitive. The probe (standard on some models, optional on others) is very useful in being able to accurately index all aspects of the block, feeding the data to the machine’s computer.
(photo courtesy Sunnen/RMC)
The menus featured on engine-builder-dedicated CNC machines include easy-to-follow prompts for viewing and data input. If you already know how to machine a block, using an automotive engine equipment maker’s CNC system is relatively easy, with no special computer language training needed.
Pictured here is the Rottler F68A CNC machining center.
(courtesy Rottler Mfg.)
Shown here is Peterson’s CNC 4030 4-axis machining center, capable of simultaneous motion control in all four axis.
(photo courtesy Peterson Machine Tool)
Sunnen/RMC V20 CNC. Note the control panel on a roll-around stand.
(photo courtesy Sunnen/RMC)
The Sunnen/RMC V40 machine.
(photo courtesy Sunnen/RMC)
Sunnen/RMC V50 machine, ideal for cylinder head porting upgrades.
(photo courtesy Sunnen/RMC)
CNC Machine Sources
FADAL MACHINING CENTERS
For more information, dial 1-800-652-0406, ext. 14419
HAAS AUTOMATION
For more information, dial 1-800-652-0406, ext. 14420
MASTERCAM/CNC SOFTWARE
For more information, dial 1-800-652-0406, ext. 14421
PETERSON MACHINE TOOL
For more information, dial 1-800-652-0406, ext. 14422
RMC
For more information, dial 1-800-652-0406, ext. 14423
ROTTLER
For more information, dial 1-800-652-0406, ext. 14424
SUNNEN PRODUCTS CO./RMC
For more information, dial 1-800-652-0406, ext. 14425
Tags: BLUEPRINTING, CNC, CNC BLOCK WORK, CNC MACHINE COSTS, FADAL, GRESSMAN POWERSPORTS, HAAS, MASTERCAM, PETERSON, RMC, ROTTLER, SUNNEN
