- Operating Principle: Step-over Turning Method
- Geometry Definition and Automated Calculations
- Tool Definition and Preparation
- Cutting Strategy and Technological Parameters
- Multi-start Worms and the “Q” Parameter (Mazak Specifics)
- Handling Workpieces Without Undercuts (Entry/Exit Motion)
- Finishing Strategy and Corrections
- Coordinate Systems and Safety (EIA/ISO vs. Mazatrol)
- Project Management and NC Code Generation
Multi-start Worms and the „Q” Parameter (Mazak Specifics)
Estimated reading: 2 minutes
Machining worms with more than one start requires precise angular indexing of the spindle. This section explains how EvoSpline controls this process and how to avoid NC code formatting errors.
How Multi-start Indexing Works
On Mazak machines (and most EIA/ISO systems), creating a multi-start worm involves repeating the entire generated tool path, but with a shifted angular start point for each subsequent lead.
First Start: The tool begins at a spindle angle of 0∘.
Subsequent Starts: The machine reads the Q address, which defines the angle the spindle must rotate before starting the next spiral.
Note: While each start is generated using the same tool offsets (step-over), their relative position is determined solely by the spindle’s starting angle.
Formatting the Q Address – The Parameter Trap
This is the most common source of errors. Depending on your machine’s configuration (usually parameter F167 bit 0), the Mazak control may expect the angle in one of two formats:
- Decimal Format (e.g., Q360.0000): The angle is entered directly in degrees with a decimal point.
- Integer Format in Thousandths (e.g., Q360000): Where a value of 360000 represents 360 degrees (1 degree = 1000 units).
Choosing the wrong format will cause the machine to either throw an error or index the starts at the wrong intervals, potentially over-cutting existing threads.
Pro Tip: The „Plasticine Test”
If you don’t have access to machine parameters or are unsure of the settings, there is a simple and safe way to verify the formatting without risking a tool crash:
- Prepare a Workpiece: Clamp any turned blank in the chuck.
- Generate Tests: Create two versions of the program in EvoSpline for a multi-start worm—one with the thousandths format checked and one without.
- Manipulate the Diameter: Set the Root diameter close to the Outside diameter (so the tool barely touches the surface or „flies” 0.1 mm above it
- Use Plasticine/Clay: Apply a thin layer of plasticine or use a marker on the workpiece surface.
- Run the Test: Run the program. Observe if the marks on the plasticine are evenly spaced according to the number of starts. If the marks overlap or appear at incorrect intervals, switch the format in the software and re-test.