Instructions for Use

NOTE: Newer chucks now have each slot marked with the letters A through D. Slot A is the slot formerly shown above marked with the punch, and the others follow in a counterclockwise order of rotation. Therefore, in the above illustration of the jaws in Normal position, slot A would be jaw 1, jaw 2 would be in slot B, jaw 3 would be in slot C and jaw 4 would be in slot D.

About self-centering chucks

Self centering chucks are designed to have all the jaws move in unison. The jaws are driven by a spiral scroll when the knurled ring is turned. Self centering chucks will never duplicate the accuracy that can be attained with jaws that are moved independently, but they will usually "get the job done", saving a machinist much time and effort.

The main purpose of a 4-Jaw self centering chuck is to hold square stock. It can also be useful in holding thin wall round tubing that will collapse easily. Round stock that is held in this chuck must be perfectly round and can not be at all elliptical or one of the jaws will not grip. The same is true for square stock; it must be very square and not at all rectangular to achieve a proper grip with all four jaws.

Chuck sizes

P/N 1075 2.5" Chuck—This chuck is designed s that the jaws can be removed and reversed to hold larger stock. In the normal position, stock from 3/32" (2.0mm) to 1-3/16" (30.16mm) can be secured. With the jaws reversed, material up to 2-1/4" (56.0mm) can be held in the 2.5" chuck, and material up to 2-3/4" can be held in the 3.1" chuck.. The hole through the center of the chuck is .687" (17.46mm) and it is threaded 3/4-16.

P/N 1076 3.1" Chuck—This chuck shares the same jaws and is used in the same way as the 2.5" chuck. It has the same center hole and minimum closing specifications. The difference is that at the large size end it will hold parts up to 1-1/2" (38.1 mm) and with the jaws reversed it can hold parts as large as 2.75" (70 mm). It is the same thickness as the 2.5" chuck so it uses no more space between centers.

Removing the Jaws

When seen from the front, turning the scroll clockwise backs the jaws out. Turn clockwise until all jaws can be removed. The jaws can be identified by the location of the teeth as noted in Figures 1 and 2 above.

Reversing the Jaws

When reversing the jaws, jaws 4 and 2 will go back into the same slots from which they were removed. Jaws 3 and 1 (from slots A and C) will swap positions. The order of installation to reverse the jaws is, therefore, 4-3-2-1 in slots D-A-B-C in that order. (See Fig. 1.)

To install the jaws in the reversed position, turn the scroll counterclockwise (when viewed from the top) until the outside tip of the spiral scroll thread is just ready to pass the slot marked "D" for the first jaw to be inserted (jaw #4). Slide jaw 4 as far as possible into the slot. Turn the scroll until the jaw is engaged.

Due to close tolerances between the slot and jaw, the most difficult part of replacing the jaws is engaging the scroll thread and first tooth of each jaw without binding. Never use force when replacing the jaws, and if binding occurs, simply back up the scroll slightly and wiggle the jaw until it is free to move in the slot. Advance the scroll counterclockwise and engage jaw #3 next in the slot that previously held jaw #1 (the slot marked with a punch or laser engraved with the letter "A"). continue to engage jaws 2 and finally 1.

When reinstalling jaws in normal position, the order of insertion reverts to 1-2-3-4 in slots A-B-C-D. (See Fig. 2.)

A set of replacement jaws is available as P/N 1177. Should repair become necessary, please return your chuck to the factory so that we may replace the jaws and check the alignment of the chuck before returning it to you. Each jaw is custom ground to the size of the slots in your chuck body to achieve the best possible fit. It is not possible to simply mail you new jaws that will accurately fit your particular chuck. In the case of a damaged chuck body, replacement of the entire chuck is usually more economical than attempting repairs.

Lubrication and maintenance

Clean chips from the jaw slots with a brush and add lubrication periodically to keep the chuck operating smoothly. To prevent rust, keep the surfaces of the chuck lightly oiled. If possible, store wrapped in the waxed paper it came in.

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