Contents

• Introduction to Driven Tools
• What Is a Driven Tool?
• CNC Lathe Driven Tool Setup: Step-by-Step
• Best Practices for Smooth Operation
• Common Pitfalls to Avoid
• Final Thoughts

Introduction to Driven Tools

With the rise of multi-functional turning centres (CNC lathes), driven tools (also called live tools) have become a core part of modern CNC lathe operations. They enable off-centre and axial machining like milling, drilling, and tapping—directly on the lathe—reducing setup times and increasing part complexity without requiring a separate machining centre.

This guide covers how to properly set up a driven tool, including machine preparation, tool alignment, and best practices for achieving optimal performance.

What Is a Driven Tool?

A driven tool is a motorized spindle mounted on the turret of a CNC lathe, designed to rotate a cutting tool during secondary operations. It receives power from the machine’s live tooling drive system, allowing rotational cutting on a lathe setup.

Driven tools are essential for:

• Side drilling and milling

• Slotting

• Engraving

• Off-centre tapping

They’re typically used on machines with C-axis or Y-axis control and turret interfaces such as VDI or BMT.

CNC Lathe Driven Tool Setup: Step-by-Step

1. Check Compatibility

Before proceeding, ensure:

• The machine supports live tooling (check for M13/M14 functionality).

• The turret station is equipped to drive the tool.

• The driven tool matches the turret’s mounting system.

• Your post-processor or G-code includes live tool activation.

2. Inspect and Assemble the Toolholder

• Examine the driven unit for signs of wear or damage.

• Install the cutting tool securely using the correct collet or chuck.

• Ensure correct tool extension - too short or long can affect performance or lead to deflection.

3. Mount the Tool onto the Turret

• Clean both the turret face and the base of the toolholder thoroughly.

• Install the unit into the turret station:

• VDI holders: Align the drive tang and lock it using the clamping mechanism.

• BMT holders: Secure using turret bolts for rigid face contact.

• Ensure proper seating - misalignment here can lead to premature wear or poor machining results.

4. Alignment and Runout Check

For systems requiring manual alignment:

• Mount a dial indicator to check runout on the cutting tool shank.

• Rotate by hand and adjust until runout is within acceptable tolerance (ideally under 0.01mm or 0.0004").

• Confirm the tool is square to the axis it will cut on, especially for side milling operations.

5. Set Tool Offsets

• Touch off the tool manually or use an automatic tool setter to determine length offsets.

• Record tool length in the appropriate geometry offset register.

• On Y-axis machines, confirm both X and Y positioning if needed for side-entry tools.

6. Program the Driven Tool

Include correct M-codes and speeds:

• M13 / M14: Start spindle (clockwise / counter-clockwise)

• M15: Stop driven spindle

• Assign proper spindle speed (S-code) and federate.

• Ensure your toolpath accounts for tool orientation and clearance.

Best Practices for Smooth Operation

• Coolant Delivery: Use internal coolant if available, especially for drilling. Make sure external nozzles are correctly aimed.

• Noise Awareness: Any unusual sound from the toolholder during operation may indicate misalignment or bearing failure.

• Consistent Torque: Always tighten the cutting tool using correct torque values to prevent slippage or damage.

• Tool Life Monitoring: Track insert or tool wear closely, especially under high-load conditions or interrupted cuts.

Common Pitfalls to Avoid

• Failing to activate the driven spindle in the G-code.

• Skipping cleaning of turret and holder mating surfaces.

• Overlooking centreline offsets on Y-axis applications.

• Using improper tool length, leading to chatter or collision.

• Applying excessive feed rates or speeds beyond toolholder limits.

Final Thoughts

Setting up a driven tool on a CNC lathe is all about precision and attention to detail. When done correctly, it transforms your lathe into a multi-tasking powerhouse—eliminating secondary setups and improving workflow efficiency.

Need help selecting a driven tool holder or cutting parameters? Please contact our technical team on 01924 869 615 or email sales@cutwel.net.