MODEL SB1231
12" 4-JAW INDEPENDENT CHUCK
Instruction Sheet
PHONE: (360) 734-1540 • www.southbendlathe.com
Independent jaw
screws for each
reversible jaw
Hardened steel jaws
for durability and
extreme clamping
Chucks are heavy! Get assistance when
force and grip
installing or removing the chuck from the
lathe. Wear heavy duty leather boots for
foot and toe protection, and keep hands and
fingers away from all pinch points. Ignoring
this warning can lead to a severe crushing
injury or finger amputation!
Direct
camlock
spindle
mounting
Jaw screw
retaining pin
with lock screws
Manufactured
with high-tech
German CNC
machinery
Specifications
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•
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•
•
•
•
•
•
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OD Clamping...... 0.69"–10.04" (17.5–255mm)
ID Clamping.......... 3.74"–10.83" (95–275mm)
Chuck Bore Diameter ................2.56" (65mm)
Chuck Outer Diameter ..........11.81" (300mm)
Maximum Speed ...........................2500 RPM*
Mounting Type......................... D1-8 Camlock
Construction..................Fine-Grain Cast-Iron
Chuck Weight......................................... 80 lbs
Chuck Shipping Weight......................... 85 lbs
Country of Origin................................ Taiwan
Fine-grain cast
iron body
Figure 1. Features.
Introduction
The Model SB1231 uses a direct mount D1-8
camlock system where the camlock studs are
directly threaded into to the chuck body instead
of being threaded into a backing plate that
is bolted to the chuck. Without using a back
plate to mount the chuck, the chuck jaws are
positioned closer to the headstock which gives
a longer distance between the jaws and the
tailstock. Another benefit is that the distance
between the jaws and the outboard spindle nose
is reduced, so if a spider support is used on the
outboard spindle, short gun barrels and other
shorter workpieces can be held at both ends.
* The maximum speed listed above is ONLY
possible with the chuck jaws and the
workpiece in complete rotational symmetry.
The workpiece weight must be within the
limits of the lathe, and the workpiece mass
must be of equal density throughout to
prevent centrifugal imbalance or radial
runout—even if a tailstock or other support
is used for additional support.
Copyright © October, 2010 by South Bend Lathe Co.
WARNING: No portion of this manual may be reproduced without written approval.
#CR13310 Printed in Taiwan
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Mfg. Since 5/10
Model SB1231
I N S T R U C T I O N S
Camlock Stud Installation
Camlock Stud Adjustment
The camlock studs that are shipped with this
chuck may be pre-installed from the factory.
If so skip this section and complete Chuck
Installation and Removal on Page 4;
otherwise, install the camlock studs as outlined
below:
If the camlock studs have been pre-installed at
the factory, or if you are installing them for the
first time, slight machining differences between
the lathe spindle and chuck can cause one or
more camlocks to lock at the incorrect location.
If any cam line stops outside of a “V” mark when
all of the camlocks have been tightened, remove
the chuck and adjust the height of the offending
stud one full turn up or down as illustrated
below. After all camlocks operate correctly,
stamp alignment marks in the chuck and spindle
to ensure that the chuck can be re-installed in
the same position after being removed.
1. Oil and thread each cam stud into the chuck
until the alignment groove is flush with the
chuck surface, as shown in Figure 2.
2. Install and tighten the locking cap screw
for each stud, making sure that the camlock
studs can slightly rotate back and forth.
Spindle Line
Initial Adjustment:
Camlock Stud Alignment
CORRECT
The Camlock Mark
Stops Between the
“V” Marks.
Groove is Flush with Chuck
Surface
Camlock Stud
Must Slightly
Rotate Back/Forth
Cap Screw
Installed & Tight
Alignment Marks
INCORRECT
The Camlock Mark
Stops After the
“V” Marks.
INCORRECT
The Camlock Mark
Stops Before the
“V” Marks.
Figure 2. Camlock stud installation.
To Correct:
To Correct:
Turn Stud One Turn Out
Turn Stud One Turn In
Figure 3. Camlock stud adjustment.
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Model SB1231
Mfg. Since 5/10
I N S T R U C T I O N S
Chuck Installation and Removal
1. DISCONNECT LATHE FROM POWER!
Do not install the chuck without having
the camlock cap screws in place or fully
tightened. Otherwise, the camlock studs may
turn with the camlocks on release, resulting in
the chuck being permanently locked onto the
spindle.
2. Lay a chuck cradle (see Figure 4) or
plywood under the chuck and over the
bedway to protect the precision ground
surfaces from damage and reduce the risk of
fingers getting pinched.
6. With the help of another person, or with the
help of a chuck cradle, align the chuck with
the spindle so the studs and camlock bores
are aligned correctly, and carefully slide the
chuck onto the lathe spindle. Never rest the
chuck on its lower studs, as shown in Figure
5, and roll or push the top of the chuck into
place on the spindle. This is a bad practice
that may damage the studs and camlock
bores.
CORRECT
INCORRECT
Figure 4. Wooden chuck support cradle.
3. Clean away debris and oily substances from
the mating surfaces of the spindle and the
chuck to ensure the best fit possible.
4. Inspect and make sure that all camlock
studs are undamaged, clean, and lightly
oiled.
5. Make sure that the camlock stud retaining
cap screws are snug, but still allow the studs
to be rotated back and forth slightly by hand.
This free-play is critical to ensure that the
camlocks tighten and lock with the studs
completely, and will release without binding.
Figure 5. Typical alignment of studs and camlock
bores.
— If a problem is found with the camlock
locking or release, remove the offending
stud and clean it with mineral spirits.
Compare it with a good stud for any
inconsistencies, and replace it if a problem
is found. Inspect the bore, cap screw, seat
depth, and threads with others that are
known to be correct. Chase all threads,
and remove any burrs or dings in the seat.
Dry out the bore with compressed air and
lightly re-lubricate with a drop or two of
machine oil or way oil.
Before turning the lathe
ON, make sure the chuck
key is removed! A thrown
chuck key can cause
serious injury or death to
the operator or bystanders.
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Mfg. Since 5/10
Model SB1231
I N S T R U C T I O N S
7. Tighten camlocks in a star pattern to draw
the chuck in evenly and reduce the chance
of misalignment. Make sure to tighten
camlocks in an incremental manner to
ensure that one camlock does not get fully
tightened before the others (i.e., snug the
camlocks on the first pass, then moderately
tighten on the next pass, then fully tighten
on the third pass).
To remove the chuck:
1. DISCONNECT LATHE FROM POWER!
2. Lay a chuck cradle or plywood under the
chuck and over the bedway to protect the
precision ground surfaces from damage and
reduce the risk of fingers getting pinched.
As you tighten the camlocks, the chuck
will seat with the spindle nose. When fully
tightened, the cam line will fall between the
two "V" marks on the spindle nose, as shown
in Figure 6.
PINCH HAZARD! Protect your hands and the
precision ground bedways with plywood or a
chuck cradle when removing the lathe chuck!
The heavy weight of a falling chuck can cause
serious injury.
3. Loosen the camlocks by turning the key
counterclockwise approximately one-third of
a turn until the mark on the camlock aligns
with the spindle mark on the spindle nose
(see Figure 7). If the stud does not freely
release from the camlock, wiggle the camlock
until it stud releases.
Cam line is between
the "V" marks
Figure 6. Camlock is fully tightened with the camlock
line positioned between the "V" marks.
— If the cam is fully tightened, but the cam
line is positioned outside of the “V” marks,
remove the chuck and adjust the height of
the offending camlock stud, as outlined in
Camlock Stud Adjustment on Page 3.
Note: Camlocks can become very tight. A cheater
pipe may be used to add leverage when
loosening.
8. When installation is complete and you are
satisfied with the results, lightly stamp a set
of alignment marks on the chuck and spindle.
Cam line is
aligned with the
spindle mark
Note: Alignment marks ensure that the
chuck can be re-installed in the correct
position every time for consistent chuck and
spindle alignment. It also allows for the same
camlocks and studs to operate together for
consistent locking and unlocking.
Figure 7. Camlock is fully loosened when the camlock
line is aligned with the spindle mark.
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Model SB1231
CAUTION: During the next step, the
Mfg. Since 5/10
I N S T R U C T I O N S
6. Following the sequence shown in Figure 8,
tighten each jaw in small increments to move
the workpiece into the required position.
Check frequently to make sure the intended
center point of the workpiece has not
chuck may come off suddenly, so it
is important that you are ready to
support its weight with a chuck cradle
to prevent crushing your fingers or
dropping the chuck.
wandered away from the spindle centerline
while the jaws are being tightened.
4. Using a dead blow hammer or other
soft mallet, lightly tap around the outer
circumference of the chuck body to break the
chuck free from the camlocks and the spindle
nose taper.
3
Hole to be
bored into
workpiece
1
5. Use a rocking motion to carefully remove the
chuck from the spindle.
— If the chuck does not immediately come
off, rotate the chuck approximately 60˚
and tap again. Make sure all the marks
on the cams and spindle are in proper
alignment for removal.
2
4
Figure 8. Tightening sequence.
Operation
Non-cylindrical parts can be held and brought
into the spindle centerline for facing or boring
The other benefit is that the majority of
7. After the workpiece is held in place by
the jaws, turn the chuck by hand and pay
attention to the workpiece alignment.
workpieces can be positioned out of the spindle
rotation axis if a bore (see Figure 9) or a step
needs to be cut into a workpiece on an outlying
edge. For the best grip possible on odd-shaped
workpieces, one or more jaws can also be rotated
180° to grab more surface area for clamping.
If all four jaws cannot be used to hold the
workpiece, you must use faceplate to reduce the
risk of a workpiece being thrown.
— If the workpiece is not correctly aligned
for your operation, turn the chuck and
make fine adjustments by slightly
loosening one jaw and tightening the
opposing jaw until the workpiece is
correctly aligned (see Figure 9 for an
example).
To clamp a workpiece in the chuck:
1. DISCONNECT LATHE FROM POWER!
2. Install a center in the tailstock.
3. Retract each jaw and place the workpiece
flat against the chuck face.
4. Slide the tailstock forward, so the tip of the
dead center applies enough pressure against
the workpiece to hold it in place, and then
lock the tailstock in position.
Figure 9. Non-concentric workpiece correctly clamped
in the 4-jaw chuck.
5. Move each jaw until it makes light contact
with the workpiece.
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Mfg. Since 5/10
Model SB1231
I N S T R U C T I O N S
Care & Maintenance
d
d
!
Always disconnect
a
machine from power before
performing maintenance or
serious personal injury may
result.
b
e
For optimum performance from your chuck,
follow the maintenance schedule below. Never
hammer on the chuck, jaws, or a workpiece that
is clamped in the chuck; and never subject the
chuck to abrasives, flame, or water.
c
Set screw
Jaw screw retaining pin
Figure 10. Chuck sequence of disassembly.
b. Back the jaws out of the chuck
c. Remove the four set screws.
Daily:
•
•
•
Check/correct loose mounting bolts.
Keep the chuck clean and oiled.
Use a vacuum, rag, or brush to clean the
chuck after use. Never use air pressure to
clean chips away from a chuck.
d. Put on safety glasses, and use a hammer
and drift punch to tap out each jaw screw
retaining pin.
•
•
Avoid leaving the chuck clamped on a
workpiece, unload the chuck jaws daily.
Make sure the chuck key is removed from
the chuck when not in use.
e. Slide the jaw screws out of their bores.
If the chuck ever becomes stiff to operate,
it may have been contaminated with metal
chips or abrasives from incorrect or infrequent
maintenance intervals. If this is the case, the
chuck must be disassembled, cleaned, and re-
lubricated.
4. Using mineral spirits, clean and dry all
parts. Inspect and fix all bores, teeth, pins,
and mating surfaces for wear, burrs, galling,
rust, or cracks.
5. Without changing the dimension of any part,
use a wire brush, emery cloth, or dressing
stones to remove all rust, burrs, or any high
spots caused by galling.
To disassemble the chuck for a full cleaning
and lubrication service:
1. DISCONNECT LATHE FROM POWER!
6. Coat all parts with any automotive NLGI #2
grease, and carefully re-assemble the chuck
in the reverse order shown in Figure 10.
2. Verify that chuck alignment marks are
present so the chuck can be re-installed in
the same position, and remove the chuck.
Stamp the marks if they do not exist.
7. Rotate the chuck key clockwise until the
lead thread of each jaw screw is seen just
entering the jaw guide, then insert each
numbered jaw into its numbered slot.
3. Leaving the camlock studs in place,
disassemble the chuck in the sequence listed
below and shown in Figure 10.
8. One at a time, hold each jaw against its jaw
screw, and rotate the chuck key clockwise to
engage the jaw screw with the jaw, then fully
thread the jaw into the chuck.
a. Place a set of wooden blocks under the
chuck so the camlock studs do not rest on
the table, and clamp the chuck to the
table as shown in Figure 10.
9. Align and re-install the chuck.
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Model SB1231
Mfg. Since 5/10
I N S T R U C T I O N S
Troubleshooting
Symptom
Possible Cause
Possible Solution
The chuck has
hard spots or binds
completely.
1. Jaw is in a poor position for
1. Re-install jaws for maximum engagement with jaw
clamping.
slot and jaw screw.
2. Lack of lubrication, rust, burr, or
2. Disassemble, de-burr, clean, and lubricate chuck.
metal shavings inside of chuck.
3. Broken tooth on the jaw or the jaw
3. Disassemble chuck and repair/replace broken part.
screw.
The workpiece slips
in the jaws.
1. Incorrect jaw or workpiece clamping
1. Re-install jaws for maximum engagement with jaw
position.
slot and jaw screw.
2. Chuck is binding before full
clamping force is achieved, or a jaw
or jaw screw is binding.
2. Chuck is loaded up with contaminants. Disassemble
and service chuck. Loosen and retighten the chuck
key several times to distribute lubricant.
3. Cutting overload.
3. Reduce cutting depth or feed rate.
Clamping accuracy
1. Workpiece improperly clamped or
1. Remove jaws, clean, de-burr, and re-install; verify
is poor.
workpiece is misaligned.
accuracy and recalibrate test/dial indicator.
2. Chuck loose; mounting is off-center,
2. Remove chuck, clean and de-burr mounting; adjust
or is improperly seated.
camlock studs, and re-install chuck.
Parts List
Parts Diagram
REF
PART #
DESCRIPTION
1
PSB1231001
PSB1231002
PSB1231003
PSB1231004
PSS02
PSB1231006
PSB1231007
PCAP09
REVERSIBLE CHUCK JAW
CHUCK BODY
JAW SCREW
JAW SCREW PIN
SET SCREW 5/16-18 X 3/8
CHUCK KEY
2
3
4
5
6
7
7
8
4
5
D1-8 CAMLOCK STUD
CAP SCREW 5/16-18 x 5/8
8
If you need help with your new chuck,
contact us at:
PHONE: (360) 734-1540
2
FAX: (360) 676-1075 (International)
FAX: (360) 734-1639 (USA Only)
EMAIL: [email protected]
3
1
6
Please Note: We included this parts breakdown for service purposes only. Since many of the parts shown are machined to
each individual chuck, they may not be available as replacement items.
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