1040 3-JAW CHUCK (3.125" O.D.) (2LB)

SHERLINE 3-Jaw Self Centering Chucks
P/N 1040 3-Jaw Chuck, 3.125" Diameter

CAUTION! DO NOT OVERTIGHTEN CHUCK. Use only moderate pressure with the Tommy Bars supplied.

IMPORTANT! DO NOT TURN THE LATHE SPINDLE ON UNLESS THE CHUCK IS TIGHTENED. Acceleration of the spindle can cause the scroll to open the chuck jaws if they are not tightened!

N0TE: To prevent permanent damage to the chuck, finished, turned or drawn stock only should be held with this chuck. For rough castings, etc., use the 4-jaw chuck.

Always wear your safety glasses when operating metalworking equipment

Instructions for Use

Three-jaw chucks are designed so that all three jaws move together and automatically center round or hexagonal parts or stock to within a few thousandths of an inch. These chucks provide the quickest and easiest way of holding work in the lathe.

The SHERLINE chuck is designed so that it can be used to clamp externally on bar stock or internally on tube stock. The P/N 1041 chuck is designed to grip from 3/32" (2mm) to 1-3/16" (30mm) diameter stock with the jaws in the normal position. The P/N 1040 chuck handles stock up to 1-1/2" (38mm) in diameter. For larger diameter work, the jaws must be reversed (See Figure 2). The reversible jaws can grip to 2-1/4" (56.0 mm) for the P/N 1041 chuck and up to 2.75" (70 mm) for the P/N 1040 chuck. The chucks have a .687" (17mm) diameter through hole with a 3/4"-16 thread.

Due to the nature of the design of a 3-jaw chuck, it cannot be expected to run perfectly true. Even 3-jaw chucks costing five times more than the one made for this lathe will have a 0.002" to 0.003" runout. If perfect accuracy is desired in a particular operation, the use of a 4-jaw chuck or a collet is recommended. Both are available for your SHERLINE Lathe.

FIGURE 1—Three-Jaw Chuck, standard jaw locations

FIGURE 2—Reversing the Chuck Jaws

NOTE: Always start with position "A". To reverse the chuck jaws, rotate the knurled scroll until the jaws can be removed. They can be easily identified by the location of the teeth to the end of the jaw (See Figures 1 and 2). To maintain chuck accuracy, the 2nd jaw must always be inserted in the same slot even when the jaws are reversed. This slot is identified by a punch mark next to the slot. Always insert the jaws in the order and location shown on the drawings. Turn the scroll counter-clockwise when viewed from the face of the chuck until the outside start of the scroll thread is just ready to pass the slot for the 1st jaw. Slide the 1st jaw as far as possible into the slot. Turn the scroll until the 1st jaw is engaged.
Due to the close tolerances between the slot and jaw, the most difficult part of replacing the jaws is engaging the scroll thread and 1st jaw tooth without binding. Therefore, never use force when replacing the jaws, and if binding occurs, back up the scroll slightly and wiggle the jaw until it is free to move in the slot. Advance the scroll and repeat for the 2nd and 3rd jaws. The scroll thread must engage the first tooth in the 1st, 2nd and 3rd jaws in order.