When Should You Use a Face Driver? Machining a Shaft End to End in One Set-Up
Updated: Oct 15
The awkward thing about shaft work is that traditional workholding blocks the tool. Whatever the jaws grip cannot be machined, so you finish one end, flip the part, re-clamp — and pay for it twice, in concentricity and in cycle time.
A face driver removes that trade-off: the part is driven directly from its end face, leaving nothing in the tool path and allowing the full outside diameter to be turned end to end in a single setup.
How a Face Driver Actually Drives the Part
Two internal components split the workholding job:
The Centre Point: Enters the centre hole in the workpiece to define the axis of rotation.
The Drive Pins: Arranged around the centre point, they bite into the end face to transmit torque.
The centre point is spring-loaded. As tailstock pressure builds, it retracts, and only then do the drive pins reach and press into the face. The sequence is locate first, drive second — meaning the true center of rotation is established entirely by the centre hole, not by the pins.
Why a Chuck Cannot Do the Whole Length in One Go
Workholding Method | 3-Jaw / Collet Chuck | Face Driver System |
Gripping Zone | Outside Diameter (blocks tool clearance) | End Face (entire OD remains completely clear) |
Process Steps | 2 setups required (turn side A, flip part, turn side B) | 1 setup required (turn full length in a single pass) |
Concentricity Risk | Setup & re-clamping error causes step runout between sides | High precision (continuous reference axis; ≤ 0.01 mm) |
Cycle Efficiency | Lost time due to reloading, re-zeroing, and test passes | Maximized output; highly suited for automated cell loading |
What Compensating Drive Pins Are For
A sawn, forged, or unmachined end face is never perfectly planar. With rigid pins, only the highest points make contact, leading to pin slipping or face crushing under heavy cutting.
Compensating drive pins float individually. Each pin retracts independently until all pins seat securely on the surface, ensuring torque is distributed evenly across the circumference. Mechanical designs use disc spring elements, while hydraulic designs equalize via interconnected fluid chambers to offer greater compensation travel on rough faces.
Face Driver and Live Centre — What is the Difference?
Face drivers and live centres function as a paired system at opposite ends of the lathe:
Face Driver (Spindle Side): Responsible for establishing the rotational centre and driving torque into the part.
Live Centre (Tailstock Side): Supports the far end of the shaft to absorb axial force, prevent chatter, and rotate smoothly with the part.
When Face Driving is the Wrong Choice
The end face must stay pristine: Drive pins bite into the material and always leave slight marks. If that face is a finished functional or cosmetic surface, face driving is unsuitable.
Extreme torque requirements exceed pin bite limits: Heavy roughing on hardened alloys may cause driver slippage; torque capability must be verified first.
No centre hole present: Face drivers require a pre-machined centre hole for accurate axis location.
End face diameter is too small: Small face diameters do not offer sufficient space for the pin circle layout.
What to Confirm Before Ordering
To help evaluate your application and receive a technical proposal, provide the following details:
Machine make, model, and spindle/tailstock interface (e.g., A2-6, MT4, HSK)
Workpiece material grade and hardness
Shaft diameter range and overall length
End-face condition (faced, sawn, or forged rough) and centre-hole dimensions
Machining operation (roughing, finishing, or grinding) and depth of cut
Whether drive-pin marks on the end face are acceptable
Face Drivers and Live Centres from Mongtec
Mongtec face drivers and live centres are engineered from high-grade German alloy steel for maximum rigidity under heavy loads.
Our face drivers feature disc spring washers and patented compensating drive pins to deliver runout accuracy within 0.01 mm. Paired with Mongtec maintenance-free live centres (runout ≤ 0.003 mm), they deliver a reliable solution for shaft turning in a single clamping.
Face driver sizes and models are listed in the Mongtec face driver catalogue; for a step-by-step method, read machining a shaft in one clamping.
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