Subscribe to Precision Engine
Sign up for our E-newsletterCOMPUTER-AIDED BLOCK MACHINING
by Mike Mavrigian
One of the prime benefits of owning a CNC machine is the capability of accurizing an engine block to “blueprint” specifications in terms of correct centerline placements.
(photo courtesy Sunnen)
A full-blown CNC machining center, such as this Sunnen/RMC V40, expands shop capabilities to include not only block and head work, but manifold decking and porting and beyond, such as fabricating special components from billet stock.
CNC: COMPUTER NUMERICAL CONTROL
A CNC machine offers an automated level of repeatable precision machining. Setup is quicker, and because of the computer programs (some included, some you can buy, and some you can input yourself with relative ease), these machines make it possible to achieve results that are not only highly precise, but repeatable from job to job. In addition to being able to precisely bore holes to size (with each hole being exactly the same), CNC programming allows you to accurately blueprint a block via existing (or self-programmed) data to achieve accurate crank centerline, cam bore centerline, cylinder bore centerline, lifter bore centerline, etc. Once you have a CNC machine, you’ll never need to waste hours measuring a performing tooling setup, and you won’t need to purchase dedicated fixtures to locate and machine correct centerlines.
CARTESIAN COORDINATE SYSTEM
Yeah, I know…for all of us who feared high-end math in school (myself included), this sounds scary at first. The Cartesian Coordinate System is “simply” the concept of creating index points on a 3-dimensional geometric shape. To map an object’s dimensions/shape, three basic axis lines are used, including x-axis, y-axis and z-axis.
The x-axis is a straight line (a line drawn between two opposing points). The y-axis is also a line drawn between two points, but this line intersects the x-axis at 90 degrees. Picture the x-axis as a line running east-to-west and the y-axis as a line running north-to-south. These two lines intersect, making a cross, creating a 2-dimensional image.
The z-axis is the height, or depth line that represents thickness dimension. In combination with the x and y axis, this creates a 3-dimensional shape. This is a super-simplified explanation, but you get the point.
A CNC machine uses these axis points in combination to control the path of the cutting bits. Higher-end machines also offer fourth and even fifth axis control (where you need to rotate a piece around its centerline, or where you need to tilt the piece relative to its axis).
WHAT’S AVAILABLE?
In addition to broad-use industrial CNC machines (that require CNC training and an understanding of G-code programming), several engine machine equipment specialty manufacturers offer machining centers with CNC capability that are dedicated to the engine builder and his specific needs. These machines are also very easy to use and require relatively minor training. For purposes of illustration, in this article we’ve included units available from Peterson Machine Tool, Rottler Manufacturing and Sunnen/RMC.
PETERSON MACHINE TOOL
Peterson offers its 4-axis CNC 4030, capable of surfacing, finish boring, chamfering, rough boring, O-ringing, machining for splayed caps, performing lower bore reliefs, stroker rod clearancing, engraving and shell milling for cap register, and engine block blueprinting.
According to Peterson, the CNC 4030 features full-conversational programming with no G-code knowledge required. An automatic tool setter offers one-touch operation, using Cat40 taper tooling. A standard digital probe system offers automated coordinate measuring, a rigid spindle and a standard 360-degree fourth-axis rotary block that allows automatic block angle positioning for a wide range of machining operations.
The Centroid Control System features include 1, 2, 3 or 4-axis simultaneous control with spindle speed control; a 15″ easy-to-read color LCD display; and easy-to-use part and tool setup menus.
ROTTLER MFG.
Rottler offers its F60 series of multi-purpose CNC machines, including the F65M, F67A, F68A and F68A 4th Axis machines.
The F65M vertical bed machining center offers machine control with manual or power feed package. Hand wheels are featured when manual operation is desired and three-axis precision ball screws. The XYZ digital readout allows blueprinting of blocks and sleeving operations where center distance is critical. Capabilities include cylinder boring, lifter bore machining, head and block surfacing, crank balancing, stroker clearancing, etc.
The F67A programmable automatic machining center uses computer machine control with Windows XP and features a 40GB hard drive and touch-screen controls.
Features include manual spindle head tilt of up to 90 degrees left/right and power drawbar quick change tool retention system. Dimensions are input through the touch screen, including bore centers, exact depth, speed, feed, etc.; bore setup for a complete bank in automatic cycle; lower bore relief (off center boring for honing clearance); multiple-pass surfacing for roughing and finishing; lifter bore machining; automatic line bore cycle; machining radius for stroker crank and connecting rod clearance, etc. The Rottler CAM CNC program allows G-code programming and file transfer with CAD/CAM programs if desired.
The F68A programmable automatic machining center also features touch-screen control, uses Windows XP format, G-code programming (if/when needed), tool change, probe system, line bore pivot table, cam boring package, dual-axis head and manifold fixture and rigid spindle.
The F68A 4th Axis programmable machining center includes all features of the F68A, plus a 360-degree fourth-axis rotary block fixture which enables automatic block angle positioning for work such as lifter boring, splayed cap conversions, etc.
SUNNEN/RMC
A selection of machines is available, including the V20, V30, V40 and V50.
The V20 and V30 are bedmill type machines, while the V40 and V50 are large machining centers with large capacity tool chambers, linear way systems and ball bearing rail systems. The V20/V30 feature box ways. All Sunnen/RMC machines accept industry-standard Cat40 tapered tooling.
The V20 features a Bridgeport-style wheel head and articulating Bridgeport style spindle.
The V30, V40 and V50 units feature a rigid style spindle, with the spindle mounted directly to the Z-axis. V20 tools install manually, while the V30 features an optional 5-place tool change that carries 5 tools at the same time for automatic sequence.
On the V40 and up, the standard is a 16-pocket tool changer. The V40HD and V50 features a 24-pocket tool changer. Swing booms are available as options for the V20 and V30.
The V40 and V50 offer the same basic capabilities, while the V40HD and V50 are intended for higher production use. Meyer noted that if you have plans to add head porting service in the future, the V50 is the best choice, since it easily accepts head porting fixturing and allows moving from 4-axis to 5-axis work.
The fourth-axis rotary block fixture (optional on V40) allows a full 360-degree rotation of the block.
V30 dimensions: 86 in. wide x 100 in. deep x 129 in. high.
Power requirements: 220 volts, 3-phase, 40 amp (single phase available at added cost)
Boring range: 0.98 in. – 6.00 in.
Max. boring depth: 10.43 in.
Table traverse (X-axis): 40.00 in.
Cross traverse (Y-axis): 20.00 in.
Vertical head travel (Z-axis): 24.00 in.
Feed rate range: 0.1 – 300 ipm
V40 dimensions: 112 in. wide x 110 in. deep x 120 in. high.
Power requirements: 220 volts, 3 phase, 40 amp (single phase available at added cost).
Boring range: 0.98 in. – 6.00 in.
Max. boring depth: 10.43 in.
Table traverse (X-axis): 40.00 in.
Cross traverse (Y-axis): 20.00 in.
Vertical head travel (Z-axis): 26.00 in.
Feed rate range: 0.1 – 800 ipm
CNC operation allows precise and repeatable cylinder rough & final boring.
(courtesy Rottler)
Although you can create your own programs for specialty work like clearancing for cranks and rods, many machines include clearancing programs for popular blocks. Simply follow the menu prompts, call up the type of block you’re working on, select the stroke clearancing program (or whatever that machine maker calls it), punch in the amount of material you wish to remove, and hit a button. The machine already knows where to mill.
(courtesy Sunnen/RMC)
Here a block deck is surfaced using CNC. Use the machine’s probe to identify where the block is located on the bed, and simply tell the machine how much to remove (and select a speed and feed rate that you desire).
(photo courtesy Rottler)
The machining center will secure the block in the correct plane, relative to the crank centerline.
(photo courtesy Rottler)
The bedplate on most CNC machines is massive, providing rigidity for precise holding of tolerances.
Of course, a rotating head allows block rotation for switching from one bank to another, etc., but a CNC controlled rotating head provides automatic rotation when the appropriate program is used.
Tooling on some machines is changed at the touch of a button, or in automatic mode, depending on the program. Some machines feature multiple-tool changers that operate so quickly, they’re difficult to photograph. The changing arm moves to the spindle, the spindle un-chucks the tool, the changer arm grabs it, removes it and stores it, grabs the next tool, feeds it to the spindle and moves away for immediate continuation of machining.
Here’s a Dart Chevy block that was lightened on a Sunnen/RMC V40 machine. A lightening program was already in storage. The operator simply tells the machine what block it’s working on. Here the block sides have been milled to remove excess weight. Gressman noted that he sometimes pulls as much as 30 lbs. from a block. The software already knows the block profile, and if any less or more material is desired for removal in certain locations, the operator can input his special needs.
The same block is shown here after the lifter valley has been milled for weight removal. The program controls the cutting in terms of locations, shape and depth, and (in the case of the Sunnen/RMC V40 used here) even rotates the block to work from one side to the other.
Tags: AVAILABLE CNC MACHINES, BLUEPRINTING, CNC, CNC EXPLAINED, GRESSMAN POWERSPORTS, PETERSON, ROTTLER, SUNNEN/RMC
