Related Manuals for Brother T-8420C
Summary of Contents for Brother T-8420C
- Page 1 T-8420C, 8450C INSTRUCTION MANUAL T-8720C, 8750C Please read this manual before using the machine. Please keep this manual within easy reach for quick reference. TWIN NEEDLE LOCK STITCHER...
- Page 2 Thank you very much for buying a BROTHER sewing machine. Before using your new machine, please read the safety instructions below and the explanations given in the instruction manual. With industrial sewing machines, it is normal to carry out work while positioned directly in front of moving parts such as the needle and thread take-up, and consequently there is always a danger of injury that can be caused by these parts.
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Page 3: Safety Instructions
) indicates something that you must do. The picture inside the circle indicates the · · · · · nature of the thing that must be done. (For example, the symbol at left means “you must make the ground connection”.) T-8420C, 8450C, 8720C, 8750C... -
Page 4: Notes On Safety
Furthermore, do not excessively bend the cords or secure them too Contact your Brother dealer or a qualified firmly with staples, otherwise there is the danger electrician for any electrical work that may need to that fire or electric shocks could occur. -
Page 5: Maintenance And Inspection
Ask your Brother dealer or a qualified electrician to carry out any maintenance and inspection of the Secure the table so that it will not move when tilting electrical system. -
Page 6: Warning Labels
The following warning labels appear on the sewing machine. Please follow the instructions on the labels at all times when using the machine. If the labels have been removed or are difficult to read, please contact your nearest Brother dealer. *Safety devices:... - Page 7 Oil pan 2478B 2509B Oil tank T-8420C, 8450C, 8720C, 8750C...
- Page 8 T-8420C, 8450C, 8720C, 8750C...
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Page 9: Table Of Contents
10-6. Needle and rotary hook timing ......39 6-2. Backtacking ............ 23 10-7. Installing the feed dog........41 6-3. Sewing condensed stitches ......24 10-8. Feed dog position ...........42 10-9. Feed dog height ..........43 10-10. Feed dog angle ..........44 11. TROUBLESHOOTING......T-8420C, 8450C, 8720C, 8750C... -
Page 10: Names Of Major Parts
Knee lifter assembly Stitch length dial Reverse lever Oil gauge window Machine pulley Alarm display (semi dry type) (10) Cotton stand (11) Stop lever (T-8450C, 8750C) Safety devices (12) Thread take-up cover (13) Finger guard (14) Belt cover T-8420C, 8450C, 8720C, 8750C... -
Page 11: Machine Specifications
1 mm Needle (DPu5) #14–#22 T-8450C -005 Max. sewing speed 3,000 sti/min Max. stitch length 5 mm Presser foot Lifting lever 7 mm height Knee lifter 13 mm Feed dog height 1 mm #14–#22 Needle (DPu5) T-8420C, 8450C, 8720C, 8750C... -
Page 12: Table And Motor
50 Hz Motor pulley 100 4,000 sti/min 60 Hz Motor pulley 85 50 Hz Motor pulley 90 3,500 sti/min 60 Hz Motor pulley 70 50 Hz Motor pulley 75 3,000 sti/min 60 Hz Motor pulley 65 T-8420C, 8450C, 8720C, 8750C... -
Page 13: Installation
If only one hand is used, the weight of the machine Contact your Brother dealer or a qualified electrician head may cause your hand to slip, and your hand for any electrical work that may need to be done. -
Page 14: Installation
Tap the head rest (3) securely into the table hole. If the head rest (3) is not pushed in as far as it will go, the machine head will not be sufficiently stable when it is tilted back. 2481B T-8420C, 8450C, 8720C, 8750C... - Page 15 (5) is at the desired position within a distance of 13 mm of the needle plate when the knee liter plate (1) is fully pressed. 9. After adjustment is completed, securely tighten the nut (9). Within 13 mm 2963M T-8420C, 8450C, 8720C, 8750C...
- Page 16 10-14 mm of deflection in the V-belt (1) when it is pressed at the midway point with a force of 5 N. 2966M 9. Belt cover bracket (1) Belt cover bracket (2) Screws [2 pcs] Ground wire 2967M T-8420C, 8450C, 8720C, 8750C...
- Page 17 2968M (1) Belt cover U (2) Screws [4 pcs] Insert the projecting part underneath the machine pulley. 2969M 11. Belt cover D (1) Belt cover D (2) Wood screws [2 pcs] (3) Washers [2 pcs] 2970M T-8420C, 8450C, 8720C, 8750C...
- Page 18 (1) Belt cover D lid 2972M Pull belt cover D (2) forward to adjust so that there is no gap between belt cover U (3) and the belt cover D lid (1). 2973M Re-tighten the wood screws. 2974M T-8420C, 8450C, 8720C, 8750C...
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Page 19: Cotton Stand
14. Cotton stand (1) Cotton stand NOTE: Securely tighten the nut (4) so that the two rubber cushions (2) and the washer (3) are securely clamped and so that the cotton stand (1) does not move. 2878M T-8420C, 8450C, 8720C, 8750C... -
Page 20: Lubrication
Use only the lubricating oil <NIPPON OIL CORPORATION Sewing Lube 10N; VG10> specified by Brother. * If this type of lubricating oil is difficult to obtain, the recommended oil to use is <Exxon Mobil Essotex SM10; VG10>. - Page 21 Apply 1 - 2 drops of oil to the places indicated by the arrows. <Minimum lubrication type only> * Do not apply oil for semi dry types. <T-8450C, 8750C> 2200B <Semi dry type and minimum lubrication type> Rotary hook race (left and right) 2485B T-8420C, 8450C, 8720C, 8750C...
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Page 22: Checking The Machine Pulley Rotating Direction
(2) GREASE indicator (red) If the GREASE indicator (2) illuminates and the buzzer sounds each time the treadle is depressed, it is time to apply 2981M grease. (See P. 31.) T-8420C, 8450C, 8720C, 8750C... -
Page 23: Preparation Before Sewing
3. Insert the needle (2) straight in as far as it will go so that the long groove is facing inward, and then securely tighten the screws (1). Long groove 2461B <T-8450C, 8750C> Long groove 2462B T-8420C, 8450C, 8720C, 8750C... -
Page 24: Removing The Bobbin
1. Open the slide plates (1) by moving them to the right and left. 2. Lift up the latch (2) of the rotary hook, and then remove the bobbin case (3). 3. Remove the bobbin. 2487B T-8420C, 8450C, 8720C, 8750C... -
Page 25: Winding The Lower Thread
* Loosen the screw (5) and move the bobbin presser (6) to adjust the amount of thread wound onto the bobbin. NOTE: More thread The amount of thread wound onto the bobbin should be a maximum of 80 % of the bobbin capacity. Less thread 2123M 2124M T-8420C, 8450C, 8720C, 8750C... -
Page 26: Installing The Bobbin
5. Pull out the thread to a length of approximately 50 mm. 6. Close the slide plates. Use bobbins (1) made of light alloy as specified by BROTHER. 2488B 2900M T-8420C, 8450C, 8720C, 8750C... - Page 27 3. Insert the bobbin case (2) into the rotary hook. 4. Push latch (9) of the rotary hook flat. 5. Close the slide plates. Use bobbins (1) made of light alloy as specified by BROTHER. 3126M <C> 3127M 2489B T-8420C, 8450C, 8720C, 8750C...
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Page 28: Threading The Upper Thread
Turn the machine pulley and raise the thread take-up (1) before threading the upper thread. This will make threading easier and it will prevent the thread from coming out at the sewing start. Thread the left-side thread first. T-8420C, 8450C, 8720C, 8750C... - Page 29 Operate the lifting lever or the knee lifter to raise the presser foot. The thread can be passed securely in between the tension discs. <T-8420C, 8720C> <T-8450C, 8750C> Pass the thread on the inside of the tab (3). T-8420C, 8450C, 8720C, 8750C...
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Page 30: Adjusting The Stitch Length
(2). * Check that the stitch length dial (2) does not rotate. Locked Unlocked 2985M 5-7. Using the knee lifter The presser foot (2) can be raised by pressing the knee lifter plate (1). 2907M 2469B T-8420C, 8450C, 8720C, 8750C... -
Page 31: Corner Sewing Method (T-8450C, 8750C)
The number of stitches of the outer needle varies according to the combination of sewing angle and stitch length. [Example] For a sewing angle of 40q and a stitch length of 2.9 mm, the number of stitches becomes 6. T-8420C, 8450C, 8720C, 8750C... -
Page 32: Sewing
4. Depress the treadle to start sewing. Lower thread Lower thread 2472B 6- 2. Backtacking When the reverse lever (1) is pressed during sewing, the feed direction will be reversed. When it is released, the feed direction will return to normal. 2986M T-8420C, 8450C, 8720C, 8750C... -
Page 33: Sewing Condensed Stitches
(Condensed stitches are sewn while the reverse lever (1) is being pressed.) * To stop sewing condense stitches and return to using the backtack function, lower the stopper (5) so that it does not touch the reverse stitching lever plate (6). 2989M T-8420C, 8450C, 8720C, 8750C... -
Page 34: Thread Tension
After the lower thread tension has been adjusted, adjust the upper thread tension so that a good, even stitch is obtained. 1. Lower the presser foot. 2. Adjust by turning the tension nut (2). Becomes stronger Becomes weaker Becomes weaker Becomes stronger 2924M T-8420C, 8450C, 8720C, 8750C... -
Page 35: Adjusting The Presser Foot Pressure
2. Turn the presser adjusting screw (2) to adjust the presser foot pressure. 3. Tighten the adjusting nut (1). Reference values Adjusting screw height For foundation Approx. 34mm For light-weight and medium- weight Approx. 34mm materials For heavy-weight Approx. 29mm materials 2925M T-8420C, 8450C, 8720C, 8750C... -
Page 36: Adjusting The Presser Foot Floating Amount (Minute Lifting Amount)
If the floating amount is too small • Ease of working (handling) will be poorer when sewing curves. If the floating amount is too large • The stitch lengths and seam lines will be unstable. 3097M T-8420C, 8450C, 8720C, 8750C... -
Page 37: Adjusting The Thread Take-Up Amount
Start of movement The thread take-up amount required will vary depending on the type of thread, the thickness of the material and the stitch length, so adjust the thread take-up amount to suit the sewing conditions. 3019M T-8420C, 8450C, 8720C, 8750C... -
Page 38: Cleaning
<Filling the oil tank> Use only the lubricating oil (NIPPON OIL CORPORATION Sewing Lube 10N; VG10) specified by Brother. * If this type of lubricating oil is difficult to obtain, the recommended oil to use is <Exxon Mobil Essotex SM10; VG10>. -
Page 39: Lubricating Via The Oil Cover (Every 6 Months)
Use only the lubricating oil <NIPPON OIL CORPORATION Sewing Lube 10N; VG10> specified by Brother. * If this type of lubricating oil is difficult to obtain, the recommended oil to use is <Exxon Mobil Essotex SM10; VG10>. -
Page 40: Applying Grease - When The Grease Indicator Illuminates (Semi Dry Type)
Note based on California law (USA) on the use and handling of Perchlorate This product contains a CR Coin Lithium Battery which contains Perchlorate Material – special handling may apply. See http://www.dtsc.ca.gov/hazardouswaste/perchlorate. T-8420C, 8450C, 8720C, 8750C... - Page 41 8. CLEANING <Applying grease> Use Brother-specified “Grease unit (SA8837-001)”. 1. Using the tube 4087M 2. Applying grease Follow the procedure below to apply grease to the places indicated by arrows on the next page. Grease Grease Insert the tip of the nozzle...
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Page 42: Resetting The Cumulative Operating Time
If the GREASE indicator (3) does not illuminate and the buzzer does not sound when the RESET switch (1) is pressed, operate the sewing machine for more than 30 seconds, and then carry out the reset procedure again. The RESET switch (1) should never be pressed except when carrying out the reset procedure after grease application. T-8420C, 8450C, 8720C, 8750C... -
Page 43: Adjusting The Rotary Hook Lubrication Amount
* Turn the adjusting screw (1) and check the lubrication amount repeatedly until the lubrication amount is correct. 4. Check the lubrication amount again after the sewing machine has been used for approximately two hours. 2497B T-8420C, 8450C, 8720C, 8750C... -
Page 44: Standard Adjustment
The motor will keep turning even after the power is Ask your Brother dealer or a qualified electrician to switched off as a result of the motor’s inertia. Wait carry out any maintenance and inspection of the until the motor stops fully before starting work. -
Page 45: Thread Take-Up Spring Tension
Thread take-up spring L (2) [for left thread] 1. Loosen the tension nut (5). 2. Use a small screwdriver to turn the tension stud (6) to Stronger adjust the tension. 3. Tighten the tension nut (5). 3017M T-8420C, 8450C, 8720C, 8750C... -
Page 46: Clearance Between Rotary Hook And Needle Plate
(1) does not lift up. If the clearance is too large • The inner rotary hook may come out from the needle plate (2). If the clearance is too small • Poor thread tightening may occur. 3056M T-8420C, 8450C, 8720C, 8750C... -
Page 47: Clearance Between Rotary Hook And Opener
Do not turn the presser bar (8) at this time. 5. Tighten the screw (7). 6. Turn the presser adjusting screw (4) to adjust the presser foot pressure, and then tighten the nut (3). Approx. 7mm 3059M T-8420C, 8450C, 8720C, 8750C... -
Page 48: Needle And Rotary Hook Timing
• Both the left and right seams will become uneven, and skipped stitches or thread breakages will occur. If the needle bar lift amount is too small • Skipped stitches and thread breakages will occur. Lower feed Needle feed 3040M T-8420C, 8450C, 8720C, 8750C... - Page 49 0.7 mm, otherwise the rotary hook tip (15) may touch the projection (D) and this could damage the rotary hook tip Mark (15). 2262B T-8420C, 8450C, 8720C, 8750C...
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Page 50: Installing The Feed Dog
(4) touches the bottom of the feed dog (1). 3. Tighten the nut (5) to secure the set screw (4). Touch * The set screw (4) is not used for installing the feed dog at an angle. 3060M T-8420C, 8450C, 8720C, 8750C... -
Page 51: Feed Dog Position
(5) and (6). If the needle plate and the feed dog are touching, loosen the screw (1) and move the feed rocker base arm (3) sideways Should not be to adjust. touching at any points 3063M T-8420C, 8450C, 8720C, 8750C... -
Page 52: Feed Dog Height
• It may be difficult to obtain uniform stitch lengths for normal feed and reverse feed. • Large variations in stitch length may occur at slow and fast sewing speeds. Lower Higher 3066M T-8420C, 8450C, 8720C, 8750C... -
Page 53: Feed Dog Angle
* In addition, when the angle of the feed dog is adjusted, the height of the feed dog will also change, so readjust the height of the feed dog. 3067M T-8420C, 8450C, 8720C, 8750C... -
Page 54: Troubleshooting
Pull out the lower thread to check that there is no slackness in the thread tension, or replace the bobbin or bobbin case. y Is the thread take-up amount too large? Adjust the thread take-up amount. 0977M T-8420C, 8450C, 8720C, 8750C... - Page 55 If sewing light or medium-weight materials, is a presser foot with slots on the underside or grooved feed dog being used? Use a presser foot without slots. Use a feed dog without grooves. Grooves Slot 2946M 2944M T-8420C, 8450C, 8720C, 8750C...
- Page 56 80 %. y Is the bobbin turning smoothly? If the bobbin is not turning smoothly, replace the bobbin. y Is a bobbin other that the light-alloy bobbins specified by Brother being used? Use only bobbins which are specified by Brother.
- Page 57 0469M The GREASE indicator on y This is a notification that it is time to apply grease. alarm display Apply grease to the sewing machine. illuminates and the buzzer sounds when the treadle is depressed. T-8420C, 8450C, 8720C, 8750C...
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Page 58: Instruction Manual
INSTRUCTION MANUAL © 2010 Brother Industries, Ltd. All Rights Reserved. T-8420C, 8450C, 8720C, 8750C SB1412-001 E This is the original instructions. 2010.05. B (1)