Instructions

WEAR YOUR
FORESIGHT IS BETTER
THAN NO SIGHT
READ INSTRUCTIONS
BEFORE OPERATING
SAFETY GLASSES
SHERLINE PRODUCTS INC. • 3235 Executive Ridge • Vista • California 92081-8527 • FAX: [phone]
Toll Free Order Line: [phone] • International/Local/Tech. Assistance: [phone] • Internet: www.sherline.com
12/8/19
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.
Jaw Opening Ranges
These chucks are designed so that the jaws can be removed
and reversed to hold larger stock.
The 2.5" 4-Jaw Chuck (P/N 1075)
With jaws in normal position: 3/32" (2mm) to 1-3/16" (30 mm)
With jaws in reverse position: 5/16" (8mm) to 2-1/4" (56 mm)
3.125" 4-Jaw Chucks (P/N 1076, 1076C, and 1078)
With jaws in normal position: 3/32" (2mm) - 1-1/2" (38mm)
With jaws in reverse position: 5/16" (8mm) - 2-3/4" (70mm)
Sherline chucks have a .687" (17 mm) through hole with
a 3/4"-16 thread for use on standard Sherline headstock
spindles. (P/N 1078 has a 22 x1.5 mm thread for use on
ER-16 collet spindles).
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 identied by the location of the
teeth as noted in Figures 1 and 2.
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 will exchange positions. The order of installation
to reverse the jaws is 4-3-2-1 in slots D-A-B-C. (See Fig.
1.) To install the jaws in the reversed position, turn the
scroll counter-clockwise (viewed from the top) until the
outside tip of the spiral scroll thread is just ready to pass
the slot for the rst 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
4-Jaw Self-Centering Chucks
P/N 1075, 1076, 1076C and 1078
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!
NOTE: Allowable chuck runout is
specified as .003" or less.
Not designed for use above
3000 RPM.
A
B
C
D
A
B
C
D
Jaw Locations
REVERSED POSITION
Jaw Number
Insertion Order
1st 2nd 3rd 4th
4 3 2 1
Rotate knurled ring
this direction to
engage jaws
Insert this
jaw 2nd
Punch Mark or Letter “A”
Spiral Scroll Teeth
Insert this
jaw 3rd
Insert this
jaw last
Insert this
jaw 1st
Jaw 3
Jaw 4Jaw 2
Jaw 1
Jaw Locations
NORMAL POSITION
Jaw Number
Insertion Order
1st 2nd 3rd 4th
1 2 3 4
Rotate knurled ring
this direction to
engage jaws
Insert this
jaw 1st
Insert this
jaw 2nd
Insert this
jaw 3rd
Insert this
jaw last
Jaw 1
Jaw 4Jaw 2
Jaw 3
Punch Mark or Letter “A”
difcult part of replacing the jaws is engaging the scroll
thread and rst 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 counter-
clockwise and engage jaw #3 next in the slot that previously
held jaw #1 (the slot marked “A”). Continue to engage jaws
2 and nally jaw 1.
When reinstalling jaws in the normal position, the order of
insertion reverts to 1-2-3-4 in slots A-B-C-D. (See Fig. 2.)
FIGURE 1—
Reversing the
chuck jaws to
hold a larger
work piece.
FIGURE 2—
Four-jaw chuck,
standard jaw
locations.