Overview

The Autobox 3 jaw self centering chuck is a K11-series scroll chuck sized for hobbyist and bench lathes. All three jaws advance and retract simultaneously via a single scroll plate, centering round and hex stock automatically with each tightening. Available in 3", 4", and 5" body diameters to match the capacity of your lathe spindle.

Available Options

• 3 inch (80mm) — K11-80 — fits smaller mini lathes and rotary table work
• 4 inch (100mm) — K11-100 — the most common size for 7x10 through 7x14 mini lathes
• 5 inch (125mm) — K11-125 — for 8x16 and similar larger bench lathes

Key Features

• Three-jaw scroll mechanism: single T-key tightens all three jaws simultaneously for fast, repeatable centering
• Runout tolerance ≤0.05mm (0.002") — consistent with K11 series specification
• Reversible jaws: standard internal jaws for gripping round and hex stock; reverse for clamping larger OD workpieces
• Hardened steel jaws — heat-treated for wear resistance
• Chuck key included — T-handle wrench ships with every unit
• Three mounting bolt holes for direct spindle nose attachment (back plate or adapter may be required — see Compatibility section)

Specifications

Jaw type: Reversible (internal + external use)
Drive: Single-scroll, 3-pinion bevel gear
Runout: ≤0.05mm (0.002")
Mounting: 3-bolt pattern, flat-back — spindle nose adapter or back plate required for most mini lathes

Compatibility

This 3 jaw self centering chuck mounts to the lathe headstock spindle nose. Compatibility depends on your spindle nose type and bolt circle diameter — most mini lathes require a threaded or D1-style adapter back plate (sold separately). The 4" (K11-100) is the most commonly used size for 7x10 through 7x14 mini lathes.

• Harbor Freight 7x10 Central Machinery (#93212) — headstock MT3 spindle, requires adapter back plate
• Harbor Freight 7x12 Central Machinery (#44142) — requires adapter back plate
• Sieg C2 / SC2 / C3 mini lathe — requires adapter back plate
• Grizzly G8688 (7x12) — requires adapter back plate
• Grizzly G0765 (7x14) — requires adapter back plate
• Autobox 7x14 / 8x16 — designed to accept K11-100 (4") and K11-125 (5") with included spindle adapter
• LittleMachineShop HiTorque 7x16 — requires adapter back plate
• Micro-Mark 7x16 — requires adapter back plate

Important: Verify your lathe's spindle nose thread or bolt circle diameter before ordering. Message us with your machine model and we will confirm the correct adapter.

What's in the Box

• 1× K11-series 3-jaw self-centering chuck (your selected size)
• 1× T-handle chuck key (wrench)
• 1× Set of reverse jaws
• 3× Mounting bolts

Note: Adapter back plate for your specific spindle nose is sold separately.

Frequently Asked Questions

Q: Do I need a back plate or adapter to mount this chuck?
A: Yes, for most mini lathes. This chuck uses a flat-back 3-bolt pattern. You will need a threaded or D1-style adapter back plate to match your lathe's spindle nose. Contact us with your lathe model and we can point you to the correct adapter.

Q: What is the difference between the 3", 4", and 5" sizes?
A: The size refers to the outer body diameter of the chuck. The 4" (K11-100) is the most common fit for 7x10 through 7x14 mini lathes. The 3" (K11-80) is for smaller machines or rotary table use. The 5" (K11-125) is suited for 8x16 and larger bench lathes where the headstock can support the added diameter and mass.

Q: Can I use this chuck to hold square or irregular stock?
A: No — a 3-jaw self-centering chuck is designed for round and hex stock only. The three jaws move simultaneously, so they cannot independently adjust to grip irregular shapes. For irregular or off-center workpieces, see our 4-jaw independent chuck.

Q: What is the runout accuracy of this chuck?
A: The K11 series is rated at ≤0.05mm (0.002") TIR. Real-world runout also depends on adapter fit, jaw condition, and workpiece surface. If you need tighter concentricity, indicate stock diameter and we can advise on jaw selection.

Why Buy from Autobox

• Ships from our US warehouse in Toledo, OH — typical 3-5 business day delivery
• US-based customer support — email us your lathe model and we'll confirm fit
• 30-day returns, no restocking fee
• K11-series chuck: the same scroll-chuck standard used in vocational programs and small machine shops across North America