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A precision mounting plate is installed to the rear of the block. This accurately locates the block to the machine’s base fixture.
A centering bar is inserted through the main bores.
The main bore centering bar is bushed to accommodate the specific block’s main bore diameter.
A camshaft tunnel centering bar helps the machine to locate the block. This bar features expandable locators that center the bar into the cam tunnel.
The machine head (in this case, a cutter head for deck surfacing) is zeroed to the block’s front resting plate.
The block is mounted into the machine, engaging the main bore bar to the front and rear table fixtures.
Block in place. Notice the cam bore centering bar.
A probe is secured to the overhead tool head and contacts the main bore bar to determine X- and Y-axes and informs the computer of main bore location.
The probe also contacts the cam bore bar. This tells the machine where the block is located.
The probe reads the deck surfaces at six points on each deck. This provides deck height and angle information to the computer.
The cutting head is fitted with the appropriate CBN or carbide cutter,
depending on block material.
The cutting head resurfaces the decks quickly. Since the machine knows main bore centerline and orientation, the decks are trued for perfect parallelism and angle. The operator can easily choose the specific deck height that’s desired. After the first deck is cut, the block is automatically rotated to proper position for cutting of the opposing deck.
The probe runs in/out in the cylinder bore to determine the Y-axis.
The probe then runs left/right to determine the X-axis. This information informs the machine of the block’s existing bore centerline location. The operator can then decide if he wants to cut at this existing centerline or at a blueprint centerline (assuming a difference is present).
The cylinder bore cutter tool is set up on a remote fixture to adjust the cutter for the desired bore diameter.
This closeup shows the dial indicator probe in contact with the cutter tip.
Once the first bore is cut, it’s a good idea to verify bore size in case further cutter tip adjustment is needed.
Bores can be cut in several passes. The user-friendly display/control center allows simple and clear communication with the operator.
This sample block’s eight bores were machined to size in a total of 4 minutes and 40 seconds.
Once the bores have been machined to the desired diameter, a chamfer-cutter is installed. The machine’s control panel prompts allow easy selection of the chamfer cut. Once the cut is selected, the machine runs automatically, chamfering an identical amount at the top of all eight cylinders without the need for the operator to baby-sit the operation.
CNC operation results in a finished block that features identical banks (decks and bores).
Lifter bores can be checked and corrected (if needed) without the need for add-on specialty fixtures. The machine’s computer is already programmed for blueprint dimensions (lifter bore centerline). Depending on the lifter diameter and oil clearance desired, the operator can quickly select these data. Once activated to run, all 16 lifter bores can be cut automatically.
Closeup of lifter bore cutter tool.
This control panel is actually fairly easy to understand and requires a relatively short learning curve. Display screen prompts guide you through each setup.
Whenever the machine is performing an operation, a real-time display shows cutting location, amount of material being removed, axis travel and cutting results.
Here a menu screen is displayed that allows you to choose the type of block at hand. Programs are already in place for each operation so a knowledge of complex computer programming is not needed.
CNC capabilities go beyond conventional block-machining. Special block-lightening programs allow you to easily remove unwanted weight from race blocks.
Here’s a Dart LS1 billet block undergoing machining at Dart’s facilities. The entire block, from a block of billet to the finished product, is handled on a single machine. (photo courtesy Dart)
Billet blocks begin with huge high-density ingot blocks of aluminum. (photo courtesy Dart)
From left to right, we see the progression of a billet aluminum block. (photo courtesy Dart)
Tags: BLOCK CORRECTIONS, BLOCK MACHINING, BLUEPRINTING, CNC, GRESSMAN POWERSPORTS, RMC
