2.5″ 4-Jaw Chucks – Various Thread


Includes 2 tommy bars, not pictured

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Product Description

This chuck combines the ease-of-use advantages of the 3-jaw chuck with some of the advantages of a 4-jaw chuck. It will automatically center square or round stock. (The stock must be accurately shaped for all four jaws to grip.) It will also grip thin-wall tubing in four places rather than three, which spreads out the load and allows more grip without crushing the tubing.

Turning the knurled portion of the outer diameter of the chuck scrolls all four jaws in unison. Included with the chuck are two Tommy bars for tightening and loosening the chuck.

Centering accuracy on self-centering chucks is to within a few thousandths of an inch. If perfect centering accuracy is required, see the section on 4-jaw independent jaw chucks.

This chuck will hold parts from 3/32″ in diameter up to 1-3/16″ with jaws in the normal position and up to 2-1/4″ with the jaws reversed.

Chucks for Sherline and Other Lathes

The chuck is available in several spindle threads for use on Sherline (3/4-16) and other machines such as old Unimat lathes (12mm x 1mm and 14mm x 1mm).
*Please note that chucks with a thread size other than 3/4″ x 16 are made to order and have a lead time of 5-7 business days.

Jaw Options

  • For those who have jobs where speed and ease of use are more important than maximum accuracy, and want a chuck that is loose right from the start (No extra charge).
    Add the note “loose jaws” to the comments box above
  • Soft (not hardened or machined) steel jaws are also available when you build your own chuck.



The improper use of machine tools and their accessories can result in serious injury. Before using this tool, thoroughly read the instructions and make sure you understand its proper and safe use.


Always wear safety glasses when operating machine tools.

Download PDF Instructions

Instructions PDF Download

Chuck Diameter 2.5″
Jaw Capacity With jaws in normal position: 3/32″ (2mm) – 1-3/16″ (30mm)

With jaws in reverse position: 5/16″ (8mm) – 2-1/4″ (56mm)

Through Hole Diameter .687″ (17mm)
Thread Size P/N 1075 – 3/4-16 (Sherline)
P/N 1077 – 12mm x 1mm (Unimat SL 1000)
P/N 1079 – 14mm x 1mm (Unimat 3 or Cowells)
Chuck Body Material 12L14 Steel
Chuck Jaws Material 12L14 Case Hardened Steel
Part No. Description Quantity
2.5″ 4 Jaw Chuck Body 3/4-16 Thread *Not sold separately
2.5″ 4 Jaw Chuck Body 12mm x 1mm Thread *Not sold separately
2.5″ 4 Jaw Chuck Body 14mm x 1mm Thread *Not sold separately
10412 2.5″ Chuck Scroll *Not sold separately 1
10413 Chuck Retainer Ring 1
11771 4-Jaw Chuck Jaw – Self Centering* 4
40580 Tommy Bar 2

*Because chuck jaws are factory ground to precisely match each chuck body you must send your chuck back to us to be fitted with new jaws. Please contact us for instructions on how to return your chuck.

Click the P/Ns below to download a zipped version of the IGS 3D CAD file. You will need to extract the zip file before viewing the IGS file.
1075 2.5″ 4-Jaw Chuck, 3/4-16 thread 3D IGS model
1077 2.5″ 4-Jaw Chuck, 12 mm x 1 mm thread 3D IGS model
1079 2.5″ 4-Jaw Chuck, 14 mm x 1 mm thread 3D IGS model-COMING SOON
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