3.1″ 4-Jaw Chuck with Pie Jaws
Includes a steel dowel pin, hex key, and 2 tommy bars, not pictured.
This chuck features a Nickel-Teflon coated chuck body for durability, rust resistance, and the special lubricity properties added by the Teflon in the coating.
Included with the chuck and jaws:
- 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 Nickel-Teflon 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 Nickel-Teflon 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.
Why pie-shaped jaws?
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.
Use on ornamental turning lathes
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.
How to Distinguish between Standard Chucks and Coated Chucks
Some of our customers have been wondering how to tell the difference between our standard chucks and those that have the electroless Nickel-Teflon 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.
Download PDF 1076C Pie Jaws Instructions
|Jaw Capacity||With jaws in normal position: 3/32″ (2mm) – 1-1/2″ (38mm)
With jaws in reverse position: 3/32″ (2mm) – 2-3/4″ (70mm)
|Through Hole Diameter||.687″ (17mm)|
|Chuck Body Material||12L14 Steel|
|Chuck Jaws Material||12L14 Case Hardened Steel|
|Coating (#1076C only)||Electroless Nickel-Teflon (#1076C only)|
|10761C||3.1″ 4 Jaw Chuck Body 3/4-16 Thread Electroless Nickel-Teflon Coated||1|
|10402C||3.1″ Chuck Scroll Electroless Nickel-Teflon Coated||1|
|10413||Chuck Retainer Ring||1|
|11445||4 Jaw Pie Chuck Master Jaw *||4|
|11453||4 Jaw Pie Chuck Top Jaw 12L14||4|
|40561||1/8″ Hex Key||1|
|11411||40 x 3/8″ Socket Head Cap Screw||4|
|114531||1/4″ x 1″ Steel Dowel Pin||1|
*Because chuck master jaws are factory ground to precisely match each chuck body you must send your chuck back to us to be fitted with new master jaws. Please contact us for instructions on how to return your chuck.
Pie Jaw Demonstration