Central Machinery 90727 User manual

3491 Mission Oaks Blvd., Camarillo, CA 93011
Visit our Web site at: http://www.harborfreight.com
Copyright©2003 by Harbor Freight Tools®. All rights reserved. No portion of this
manual or any artwork contained herein may be reproduced in any shape or form
without the express written consent of Harbor Freight Tools.
For technical questions, please call 1-800-444-3353.
®
Model 90727
ASSEMBLY AND OPERATING INSTRUCTIONS
8” SLOW SPEED
INDUSTRIAL GRINDER
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PRODUCT SPECIFICATIONS
SAVE THIS MANUAL
You will need this manual for the safety warnings and precautions, assembly,
operating, inspection, maintenance and cleaning procedures, parts list and as-
sembly diagram. Keep your invoice with this manual. Write the invoice number
on the inside of the front cover. Keep this manual and invoice in a safe and dry
place for future reference.
GENERAL SAFETY RULES
WARNING!
READ AND UNDERSTAND ALL INSTRUCTIONS
Failure to follow all instructions listed below may result in
electric shock, fire, and/or serious injury.
SAVE THESE INSTRUCTIONS
WORK AREA
1. Keep your work area clean and well lit. Cluttered benches and dark areas
invite accidents.
2. Do not operate power tools in explosive atmospheres, such as in the
presence of flammable liquids, gases, or dust. Power tools create sparks
which may ignite the dust or fumes.
3. Keep bystanders, children, and visitors away while operating a power tool.
Distractions can cause you to lose control. Protect others in the work area from
debris such as chips and sparks. Provide barriers or shields as needed.
SKU 90727 PAGE 2
Motor 120 V, 3/4 HP, 60 Hz, 1440 Watts
RPM 1725 RPM
Amp Draw 12 Amps (load)
Power Cord 7’, 1” Long, 16 AWG / 3C SJT Cord
Overall Dimensions 21-1/4” W x 12-1/2” H x 12-1/4” H
Base Dimensions 8-5/8” x 7-1/8” L
Spindle Diameter 5/8”
Mounting Holes .39 inches Dia. (2)
Weight 82.35 Lbs.
Lightbulb 40W (or less) Type A (Not Included)
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ELECTRICAL SAFETY
4. Grounded tools must be plugged into an outlet properly installed and
grounded in accordance with all codes and ordinances. Never remove the
grounding prong or modify the plug in any way. Do not use any adapter
plugs. Check with a qualified electrician if you are in doubt as to whether
the outlet is properly grounded. If the tools should electrically malfunction or
break down, grounding provides a low resistance path to carry electricity away
from the user.
5. Double insulated tools are equipped with a polarized plug (one blade is
wider than the other). This plug will fit in a polarized outlet only one way. If
the plug does not fit fully in the outlet, reverse the plug. If it still does not
fit, contact a qualified electrician to install a polarized outlet. Do not
change the plug in any way. Double insulation eliminates the need for the
three wire grounded power cord and grounded power supply system.
6. Avoid body contact with grounded surfaces such as pipes, radiators,
ranges, and refrigerators. There is an increased risk of electric shock if your
body is grounded.
7. Do not expose power tools to rain or wet conditions. Water entering a power
tool will increase the risk of electric shock.
8. Do not abuse the Power Cord. Never use the Power Cord to carry the tools
or pull the Plug from an outlet. Keep the Power Cord away from heat, oil,
sharp edges, or moving parts. Replace damaged Power Cords immedi-
ately. Damaged Power Cords increase the risk of electric shock.
9. When operating a power tool outside, use an outdoor extension cord
marked “W-A” or “W”. These extension cords are rated for outdoor use, and
reduce the risk of electric shock.
PERSONAL SAFETY
10. Stay alert. Watch what you are doing, and use common sense when oper-
ating a power tool. Do not use a power tool while tired or under the influ-
ence of drugs, alcohol, or medication. A moment of inattention while operat-
ing power tools may result in serious personal injury.
11. Dress properly. Do not wear loose clothing or jewelry. Contain long hair.
Keep your hair, clothing, and gloves away from moving parts. Loose
clothes, jewelry, or long hair can be caught in moving parts.
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12. Avoid accidental starting. Be sure the Power Switch is off before plugging
in. Carrying power tools with your finger on the Power Switch, or plugging in
power tools with the Power Switch on, invites accidents.
13. Remove adjusting keys or wrenches before turning the power tool on. A
wrench or a key that is left attached to a rotating part of the power tool may result
in personal injury.
14. Do not overreach. Keep proper footing and balance at all times. Proper
footing and balance enables better control of the power tool in unexpected
situations.
15. Use safety equipment. Always wear ANSI approved safety goggles. Dust
mask, non-skid safety shoes, hard hat, or hearing protection should be used if
necessary.
TOOL USE AND CARE
16. Use clamps (not included) or other practical ways to secure and support
the workpiece. Holding the work by hand or against your body is unstable and
may lead to loss of control.
17. Do not force the tool. Use the correct tool for your application. The correct
tool will do the job better and safer at the rate for which it is designed.
18. Do not use the power tool if the Power Switch does not turn it on or off.
Any tool that cannot be controlled with the Power Switch is dangerous and must
be replaced.
19. Disconnect the Power Cord Plug from the power source before making any
adjustments, changing accessories, or storing the tool. Such preventive
safety measures reduce the risk of starting the tool accidentally.
20. Store idle tools out of reach of children and other untrained persons. Tools
are dangerous in the hands of untrained users.
21. Maintain tools with care. Keep cutting tools sharp and clean. Properly
maintained tools with a sharp cutting edge are less likely to bind and are easier
to control. Do not use a damaged tool. Tag damaged tools “Do not use” until
repaired.
22. Check for misalignment or binding of moving parts, breakage of parts, and
any other condition that may affect the tool’s operation. If damaged, have
the tool serviced before using. Many accidents are caused by poorly main-
tained tools.
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23. Use only accessories that are recommended by the manufacturer for your
model. Accessories that may be suitable for one tool may become hazardous
when used on another tool.
SERVICE
24. Tool service must be performed only by qualified repair personnel. Service
or maintenance performed by unqualified personnel could result in a risk of injury.
25. When servicing a tool, use only identical replacement parts. Follow
instructions in the “Inspection, Maintenance, And Cleaning” section of this
manual. Use of unauthorized parts or failure to follow maintenance instructions
may create a risk of electric shock or injury.
SPECIFIC SAFETY RULES
1. Maintain labels and nameplates on the Grinder. These carry important infor-
mation. If unreadable or missing, contact Harbor Freight Tools for a replacement.
2. Always wear ANSI approved safety goggles and heavy work gloves when
using the Grinder. Using personal safety devices reduce the risk for injury.
Safety impact eye goggles and heavy work gloves are available from Harbor
Freight Tools.
3. Maintain a safe working environment. Keep the work area well lit. Make sure
there is adequate surrounding workspace. Always keep the work area free of
obstructions, grease, oil, trash, and other debris. Do not use a power tool in
areas near flammable chemicals, dusts, and vapors. Do not use this product in a
damp or wet location.
4. Always maintain a firm grip on the workpiece with both hands to resist
starting torque.
5. Always keep the extension cord away from moving parts on the tool.
6. Make sure you are prepared to begin work before turning on the Grinder.
7. Keep all guards and eyeshields in place and in working order. Pieces of the
grinding wheels and/ or the item you are grinding may fly off. Keeping the guards
and eyeshields in good working order (in addition to wearing appropriate safety
gear) helps prevent severe injury or blindness from fast moving objects.
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7. Never leave the Grinder unattended when it is plugged into an electrical
outlet. Turn off the tool, and unplug it from its electrical outlet before leaving.
8. Always unplug the Grinder from its electrical outlet before performing any
inspection, maintenance, or cleaning procedures.
9. WARNING! Some dust created by power sanding, sawing, grinding, drilling,
and other construction activities, contain chemicals known (to the State of Cali-
fornia) to cause cancer, birth defects or other reproductive harm. Some ex-
amples of these chemicals are: lead from lead-based paints, crystalline silica
from bricks and cement or other masonry products, arsenic and chromium from
chemically treated lumber. Your risk from these exposures varies, depending on
how often you do this type of work. To reduce your exposure to these chemicals:
work in a well ventilated area, and work with approved safety equipment, such as
those dust masks that are specially designed to filter out microscopic particles.
(California Health & Safety Code 25249.5, et seq.)
10. WARNING! People with pacemakers should consult their physician(s)
before using this product. Operation of electrical equipment in close proximity to
a heart pacemaker could cause interference or failure of the pacemaker.
SKU 90727 PAGE 6
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GROUNDING
WARNING!
Improperly connecting the grounding wire can result in the risk of electric
shock. Check with a qualified electrician if you are in doubt as to whether the
outlet is properly grounded. Do not modify the power cord plug provided with
the tool. Never remove the grounding prong from the plug. Do not use the
tool if the power cord or plug is damaged. If damaged, have it repaired by
a service facility before use. If the plug will not fit the outlet, have a proper
outlet installed by a qualified electrician.
GROUNDED TOOLS: TOOLS WITH THREE PRONG PLUGS
1. Tools marked with “Grounding Required” have a three wire cord and three prong
grounding plug. The plug must be connected to a properly grounded outlet. If
the tool should electrically malfunction or break down, grounding provides a low
resistance path to carry electricity away from the user, reducing the risk of elec-
tric shock. (See Figure A.)
2. The grounding prong in the plug is connected through the green wire inside the
cord to the grounding system in the tool. The green wire in the cord must be the
only wire connected to the tool’s grounding system and must never be attached
to an electrically “live” terminal. (See Figure A.)
3. Your tool must be plugged into an appropriate outlet, properly installed and
grounded in accordance with all codes and ordinances. The plug and outlet
should look like those in the following illustration. (See Figure A.)
FIGURE A
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FIGURE B
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DOUBLE INSULATED TOOLS: TOOLS WITH TWO PRONG PLUGS
4. Tools marked “Double Insulated” do not require grounding. They have a special
double insulation system which satisfies OSHA requirements and complies with
the applicable standards of Underwriters Laboratories, Inc., the Canadian
Standard Association, and the National Electrical Code. (See Figure B.)
5. Double insulated tools may be used in either of the 120 volt outlets shown in the
following illustration. (See Figure B.)
EXTENSION CORDS
1. Grounded tools require a three wire extension cord. Double Insulated tools
can use either a two or three wire extension cord.
2. As the distance from the supply outlet increases, you must use a heavier gauge
extension cord. Using extension cords with inadequately sized wire causes a
serious drop in voltage, resulting in loss of power and possible tool damage.
(See Figure C, next page.)
3. The smaller the gauge number of the wire, the greater the capacity of the cord.
For example, a 14 gauge cord can carry a higher current than a 16 gauge cord.
(See Figure C.)
4. When using more than one extension cord to make up the total length, make
sure each cord contains at least the minimum wire size required.
(See Figure C.)
5. If you are using one extension cord for more than one tool, add the nameplate
amperes and use the sum to determine the required minimum cord size.
(See Figure C.)
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6. If you are using an extension cord outdoors, make sure it is marked with the
suffix “W-A” (“W” in Canada) to indicate it is acceptable for outdoor use.
7. Make sure your extension cord is properly wired and in good electrical condition.
Always replace a damaged extension cord or have it repaired by a qualified
electrician before using it.
8. Protect your extension cords from sharp objects, excessive heat, and damp or
wet areas.
SKU 90727 PAGE 9
FIGURE C
SYMBOLOGY
Double Insulated
Canadian Standards
Association
Underwriters
Laboratories, Inc.
Volts Alternating Current
Amperes
No Load Revolutions
per Minute (RPM)
noxxxx/min.
A
V ~
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UNPACKING
When unpacking, check to make sure all the parts shown on the Parts List on page 16
are included. If any parts are missing or broken, please call Harbor Freight Tools at the
number shown on the cover of this manual as soon as possible.
ASSEMBLY AND OPERATING INSTRUCTIONS
NOTE: For additional information regarding the parts listed in the following pages, refer
to the Assembly Diagram on page 14.
1. CAUTION: Always make sure the Power Cord of the Grinder is unplugged from
its electrical outlet prior to making any adjustments to the tool.
SKU 90727 PAGE 10
Grinder
Lamp (62)
Eyeshield (30)
Water Tray (69)
Right Tool
Rest (49)
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SKU 90727 PAGE 11
ASSEMBLY AND OPERATING INSTRUCTIONS (continued)
Note: After unpacking the tool, clean off the factory protective coating with a soft cloth
moistened with kerosene. Do not use gasoline, acetone, or lacquer thinner as they will
damage the Grinder finish.
Note: First, mount the Grinder to a level, flat, secure work surface using the two
mounting holes. The mounting surface must be capable of supporting the weight of the
Grinder and workpiece.
Assembling the Tool Rests
Note: The Tool Rest Arms (42,50) are interchangeable and may be used on either side.
The Left Tool Rest (43) has threaded holes on its right side. The Right Tool Rest (49)
has a thread holes on its left side.
1. Attach the Right Tool Rest (49) to
one of the Tool Rest Arms (42,50) with
one bolt and washer.
2. Attach the Right Tool Rest Assembly
( Right Tool Rest (49) & Tool Rest Arm (42,50)
to the inside of the Right Wheel Guard (22)
and fasten with two bolts and two washers.
See FIGURE 1.
Do not completely tighten the hardware.
3. Attach the Left Tool Rest Assembly to
the other side as explained above.
4. By loosening the two bolts, adjust
each Tool Rest so that they fit slightly below the
centerline of the wheel, and as close as possible to the Grinding Wheel (8). This will
give maximum support to the workpiece. Always maintain a distance of 1/8” or less
between the Grinding Wheel (8) and the inside edge of the Tool Rest.
5. When the each Tool Rest is correctly positioned, tighten the hardware.
Note: As the Grinding Wheel (8) wears down and becomes smaller from use, re-adjust
the Tool Rest.
Note: Freehand grinding without the use of the tool rest should always be done on the
lower quarter of the wheel.
FIGURE 1
Right Tool
Rest (49)
Tool Rest
Arm (42,50)
Right Wheel
Guard (22)
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SKU 90727 PAGE 12
ASSEMBLY AND OPERATING INSTRUCTIONS (continued)
Assembling Spark Guards
See the Assembly Drawing on page 16.
1. Mount the Left Spark Guard (16) to the left of the right side of the Left Wheel
Guard (13) as shown in the Assembly Drawing, using one bolt and one washer. Adjust
the Spark Guard as close as possible to the Grinding Wheel (8) to protect the operator’s
hand.
2. Repeat the same process with the Right Spark Guard (21), on the left side of the
Right Wheel Guard (22).
Eye Shield Assembly
Warning!! Even though your Grinder is equipped with Eye Shields, you must always
wear ANSI approved safety goggles.
1. Attach the long end of the Right Mounting Rod (41)
to the side of the Right Wheel Guard (22) with
one screw and washer. Position it so that
the “L” shaped end of the Rod
is pointed out and away from
the machine as shown in
FIGURE 2.
2. Insert the “L” shaped end into the
hole on the Frame of the Eye
Shield (30), and secure it with one
small screw, washer, and nut.
3. Repeat the process on the other
side.
Note: By loosening the hardware you
just installed, you can adjust the Eye Shields.
FIGURE 2
Rod Bracket
Right Mounting
Rod (41)
Frame
Eye Shield
Right Wheel Guard (22)
Dressing a Grinding Wheel
To dress the wheel, set the Wheel Dresser (86) on
the tool rest until it just touches the high point
on the face of the Wheel. Dress the Wheel by
moving the Wheel Dresser back and forth.
Continue the operation until the face of the
Grinding Wheel (8) is clean and the corners
of the Wheel are square.
See FIGURE 3.
FIGURE 3
Position of
Wheel Dresser
on the Tool Rest.
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3 screws
FIGURE 4
Changing Grinding Wheels
Warning! Disconnect the Grinder from the power source before changing grinding wheels.
1. Remove the 3 screws shown in FIGURE 4 to remove the Left
Cover (3).
2. Prevent the Shaft from rotating by placing a wedge
between the Grinding Wheel (8) and the Tool Rest
(43).
3. To replace the Wheel on the left side of the
Grinder, use the Wrench (91) to turn the Hex Nut
(5) clockwise to loosen and remove the Hex Nut
(5). Remove the Wheel Flange (4), and the Wheel
Bushing (6), and then the Grinding Wheel.
4. Replace with a new Grinding Wheel and replace the Wheel
Flange (4), and the Wheel Bushing (6). Next, replace and
tighten the Hex Nut (5). Remove the wedge.
Warning! Do not overtighten the Hex Nut (5) when installing Grinding Wheels. Tighten the
nut just enough to drive the wheel and prevent slippage.
Note: The procedure for the right side Grinding Wheel is identical.
Warning! Always perform a “Ring Test” on the grinding wheel when changing or checking
its condition. Suspend the wheel on a screwdriver (not included) or something
similar. Then, tap the wheel with the handle of another screwdriver. A cracked
wheel will produce a dull sound, while a solid one will ring. Do not use a cracked
or damaged wheel.
Operation
Note: On the rear of each Grinding Wheel Cover is a dust port for attaching a dust collection
system to the Grinder.
Additional Grinding Wheel Warnings
1. Do not use accessories or attachments with this Grinding Wheel or severe injuries may
result.
2. Always keep the Wheels properly dressed.
3. Do not force the workpiece against a cold wheel; Always run the Wheel to idle speed
before making contact with a workpiece.
4. Make sure you’re using a balanced Wheel. They will eliminate most vibration and ensure
you more accurate work.
Operation
Warning!! Even though your Grinder is equipped with Eye Shields, you must always wear
ANSI approved safety goggles.
1. When sharpening a tool or bit, the Tool Rest should be positioned a little below the center
of the grinding wheel, adjusted so the edge of the Tool Rest is as close as possible to the
Grinding Wheel. This will allow maximum support.
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ASSEMBLY AND OPERATING INSTRUCTIONS (continued)
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SKU 90727 PAGE 14
INSPECTION, MAINTENANCE, AND CLEANING
1. WARNING! Make sure the Power Switch (64) of the Grinder, is in its “OFF”
position and that the tool is unplugged from its electrical outlet before performing
any inspection, maintenance, or cleaning procedures.
2. BEFORE EACH USE, inspect the general condition of the Grinder. Check for
loose screws, misalignment or binding of moving parts, cracked or broken parts,
damaged electrical wiring, and any other condition that may affect its safe opera-
tion. If abnormal noise or vibration occurs, have the problem corrected before
further use. Do not use damaged equipment.
3. Inspect the Grinding Wheels before each use and make sure they are not too
worn or damaged. Dress the wheels according to the instructions on page 12 if
needed. If a Wheel is damaged, replace it with a new Wheel.
2. As the Grinding Wheel (8) wears down and becomes
smaller from use, re-adjust the Tool Rest (43). Always
maintain a distance of 1/8” or less between the Grinding
Wheel (8) and the inside edge of the Tool Rest.
3. Plug in the Grinder. Lift the safety cover over the On/Off
Switch (64), and flip the switch up to start the Grinder.
See FIGURE 5.
4. After the wheel reaches idle speed, put the object you wish
to grind on the Tool Rest and slowly push it forward to make
contact with the Grinding Wheel. Do not force the object.
Let the wheel grind at its own pace.
5. When you are finished, lift the safety cover over the Switch (64), turn off the Grinder,
and cover the switch. Unplug the unit when not in use.
ASSEMBLY AND OPERATING INSTRUCTIONS (continued)
FIGURE 5
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SKU 90727 PAGE 15
THE MANUFACTURER AND/OR DISTRIBUTOR HAS PROVIDED THE PARTS LIST AND ASSEM-
BLY DIAGRAM IN THIS MANUAL AS A REFERENCE TOOL ONLY. NEITHER THE MANUFACTURER
OR DISTRIBUTOR MAKES ANY REPRESENTATION OR WARRANTY OF ANY KIND TO THE BUYER
THAT HE OR SHE IS QUALIFIED TO MAKE ANY REPAIRS TO THE PRODUCT, OR THAT HE OR
SHE IS QUALIFIED TO REPLACE ANY PARTS OF THE PRODUCT. IN FACT, THE MANUFACTURER
AND/OR DISTRIBUTOR EXPRESSLY STATES THAT ALL REPAIRS AND PARTS REPLACEMENTS
SHOULD BE UNDERTAKEN BY CERTIFIED AND LICENSED TECHNICIANS, AND NOT BY THE
BUYER. THE BUYER ASSUMES ALL RISK AND LIABILITY ARISING OUT OF HIS OR HER REPAIRS
TO THE ORIGINAL PRODUCT OR REPLACEMENT PARTS THERETO, OR ARISING OUT OF HIS
OR HER INSTALLATION OF REPLACEMENT PARTS THERETO.
PLEASE READ THE FOLLOWING CAREFULLY
PARTS LIST
Part No. Description Part No. Description Part No. Description
1 Screw M6 32 Lock Washer 63 ` Lock Washer
2 Tooth Washer 33 Hex Bolt M6 64 Switch
3 Left Cover 34 Flat Washer 65 Ext. Tooth Washer
4 Wheel Flange 35 Lock Washer 66 Screw M5
5 Hex Nut M14 36 Hex Nut M4 67 Water Tray Plate
6 Wheel Bushing 37 Left Mounting Rod 68 Screw M5
7 Label 38 Rod Bracket 69 Water Tray
8 Grinding Wheel 39 Flat Washer 70 Base Plate
9 Warning Label 40 Hex Bolt M8 71 Rubber Washer
10 Rotation Label 41 Right Mounting Rod 72 Ext. Tooth Washer
11 Screw M6 42 Left Tool Arm 73 Screw M5
12 Lock Washer 43 Left Tool Rest 74 Screw M5
13 Left Wheel Guard 44 Flat Washer M8 75 Lock Washer
14 Flat Washer 45 Hex Bolt M8 76 Capacitor Clamp
15 Hex Nut M6 46 Flat Washer 5/16 77 Capacitor
16 Left Spark Arrestor 47 Knob 5/16” x 18 78 Hex Bolt M8
17 Flat Washer 48 Table 79 Lock Washer
18 Hex Bolt M8 49 Right Tool Rest 80 Ele. Cable Assy.
19 Motor Warning Label 50 Right Tool Arm 81 Base
20 Motor Assy. 51 Bolt M6 82 Clamping Plate
21 Right Spark Arrestor 52 Lock Washer 83 Clamp
22 Right Wheel Guard 53 Flat Washer 84 Ext. Tooth Washer
23 Grinding Wheel 54 Bearing Housing 85 Screw M5
24 Label 55 Wave Washer 86 Wheel Dresser
25 Right Cover 56 Bearing 87 Wh.Dresser Blade
26 Hex Nut M14 57 Stator 88 Wh.Dresser Handle
27 Bolt M4 58 Rotor 89 Hex Screw M6
28 Bolt M6 59 Retaining Ring (shaft) 90 Set Screw M6
29 Eye Shield Plate 60 Centrifugal Switch 91 Wrench
30 Eye Shield 61 Lamp Warning Label
31 Flat Washer 62 Lamp Assy.
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SKU 90727 PAGE 16
ASSEMBLY DIAGRAM
NOTE: Some parts are listed and shown for illustration purposes only, and are not
available individually as replacement parts.
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