Includes 2 tommy bars, not pictured

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.

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.

• 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 below
• Soft (not hardened or machined) steel jaws are also available when you build your own chuck.

Includes a steel dowel pin, hex key, and 2 tommy bars, not pictured.

This chuck features a Electroless Nickel coated chuck body for durability and rust resistance.

• 1 1/4" x 1" steel dowel pin that is used to adjust the jaws during installation and to chuck up on while boring and turning the jaws
• 1 1/8" hex key for tightening the 4-40 x 3/8" jaw mounting screws
• 2 spindle or "Tommy" bars for loosening and tightening the chuck

Because the jaws are meant to be bored to size for particular jobs, eventually they will need to be replaced. The replacement set P/N 1143-4P can be installed on your existing 1076C Electroless Nickel coated chuck body and master jaws. They are NOT intended for use on the standard 1076 chuck body.

NOTE: These jaws are designed to be used ONLY on our Electroless Nickel coated chuck P/N 1076C, and master jaws are custom fitted to each body, so master jaws (11445-P) are not available for purchase separately.

First developed by watch and clock makers, chucks with pie-shaped jaws offer two main advantages. Boring the unhardened jaws to hold a particular diameter part means that instead of gripping the part at only three or four tiny contact points, they grip the part all the way around its diameter. This increased gripping area allows for much less clamping pressure and less chance of deforming a gear or other delicate part held in the chuck. In addition, because the face is bored to an exact and consistent depth, placing additional parts in the chuck for turning or milling means each part surface is held at exactly the same depth as the previous parts, saving setup time.

We decided to make pie jaws for our four-jaw self-centering chuck after a request by David Lindow, the owner of Lindow Machine Works, Maker of Modern Rose Engine Lathes, (https://lindowmachineworks.com/lindow-rose-engine-menu/). Ornamental turners need a chuck that can firmly grip wooden stock without damaging the surface. In addition to David’s request, we had also received several requests from our horological customers who were looking for a chuck similar to the Swiss-made watchmaker's scroll chuck. We designed our pie jaws in both form and function after the Swiss chucks.

Some of our customers have been wondering how to tell the difference between our standard chucks and those that have the Electroless Nickel coating. Standard chucks have darker markings than the coated chucks (See Figure 1. Click on photo to view a larger image).

Here, at Sherline Products, each of our chucks is laser engraved with a company mark, chuck size, and jaw location. During the laser marking process the laser removes a bit of the surface and darkens the material below (Figure 1, left). When chucks are sent out to receive the Nickel-Teflon finish the coating process changes the dark engraved markings to a noticeably lighter finish (Figure 1, right).

There is also a subtle change in the color of the chuck, but in the absence of being able to compare them side by side, the most evident way to tell whether you have a coated chuck, or not, is to check the color of the laser markings.