Brother T-8421B Instructions Manual
  1. Manuals
  2. Brands
  3. Brother Manuals
  4. Sewing Machine
  5. T-8421B
  6. Instructions manual

Brother T-8421B Instructions Manual

Twin needle direct drive lock stitcher with thread trimmer and with large hook
Hide thumbs Also See for T-8421B:
Table of Contents

Advertisement

Quick Links

T-8421B
TWIN NEEDLE DIRECT DRIVE LOCK STITCHER
T-8422B
TWIN NEEDLE DIRECT DRIVE LOCK STITCHER
WITH THREAD TRIMMER
T-8452B
TWIN NEEDLE DIRECT DRIVE SPLIT NEEDLE BAR
LOCK STITCHER WITH THREAD TRIMMER
T-8722B
TWIN NEEDLE DIRECT DRIVE LOCK STITCHER
WITH LARGE HOOK AND THREAD TRIMMER
T-8752B
TWIN NEEDLE DIRECT DRIVE SPLIT NEEDLE BAR
LOCK STITCHER WITH LARGE HOOK
AND THREAD TRIMMER

Advertisement

Table of Contents
loading

Related Manuals for Brother T-8421B

Summary of Contents for Brother T-8421B

  • Page 1 T-8421B TWIN NEEDLE DIRECT DRIVE LOCK STITCHER T-8422B TWIN NEEDLE DIRECT DRIVE LOCK STITCHER WITH THREAD TRIMMER T-8452B TWIN NEEDLE DIRECT DRIVE SPLIT NEEDLE BAR LOCK STITCHER WITH THREAD TRIMMER T-8722B TWIN NEEDLE DIRECT DRIVE LOCK STITCHER WITH LARGE HOOK AND THREAD TRIMMER...
  • 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.

  • 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-8421B, 8422B, 8452B, 8722B, 8752B...
  • Page 4 Contact your Brother dealer or a qualified shocks could occur. electrician for any electrical work that may need to be done.
  • Page 5 When threading the needle power switch. Then contact your nearest Brother When replacing the bobbin and needle dealer or a qualified technician. When not using the machine and when leaving...
  • Page 6 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. Be sure to connect the ground. If the ground connection is not...

  • Page 7: Table Of Contents

    5-4. Using the lower thread counter ...... 29 6. USING THE OPERATION PANEL (ADVANCED OPERATIONS) ....6-1. Names and functions........30 6-2. Adjusting the needle up stop position..... 31 6-3. LOCK key ............31 6-4. Resetting all settings to their defaults..... 31 T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 8: Machine Specifications

    Standard hook Large hook Stitch function Fixed needle bar Split needle bar Thread trimmer Quick reverse Thread wiper Lubrication type Minimum lubrication Semi dry For light-weight and For foundation For heavy-weight materials medium- weight materials T-8421B, 8422B, 8452B, 8722B, 8752B...
  • Page 9 1,000 rpm Max. stitch length 7 mm Presser foot Lifting lever 7 mm height Knee lifter 10 mm Feed dog height 1 mm Needle (DP×5) #11–#16 #14–#22 Motor AC servo motor (4-pole, 550W) Control circuit Microprocessor T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 10: Names Of Major Parts

    Power switch Stitch length dial (10) Reverse lever (11) Oil gauge window (12) Machine pulley (13) Operation panel (14) Cotton stand (15) Stop lever (T-8452B, 8752B ) Safety devices (16) Thread take-up cover (17) Finger guard T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 11: Installation

    The machine may operate if the treadle is depressed by mistake, which could result in injury. Contact your Brother dealer or a qualified electrician for any electrical work that may need to be done. Use both hands to hold the machine head when tilting it back or returning it to its original position.

  • Page 12: Installation

    2873M 3-2. Installation 1. Control box (1) Control box (2) Bolts [3 pcs] (3) Nuts [3 pcs] (4) Spring washers [3 pcs] (5) Washers [3 pcs] 2. Connecting rod (6) Connecting rod (7) Nut 2091M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 13: Power Switch

    (2) Head cushions (right) [2 pcs] (3) Oil pan (4) Oiler 2874M 5. Rubber cushions (1) Rubber cushions [2 pcs] (2) Nails [4 pcs] 6. Knee lifter complying bar (3) Knee lifter complying bar 2875M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 14: Machine Head

    9. 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-8421B, 8422B, 8452B, 8722B, 8752B...
  • 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 2882M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 16: 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 17 Apply 1 - 2 drops of oil to the places indicated by the arrows. 2885M <Minimum lubrication type only> * Do not apply oil for semi dry types. <T-8452B, 8752B> <Semi dry type and minimum lubrication type> Rotary hook race (left and right) 2886M 2887M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 18: Connecting The Cords

    CAUTION Contact your Brother dealer or a qualified electrician for any electrical work that may need to be done. Do not connect the power cord until all cords have been connected. The machine may operate if the treadle is depressed by mistake, which could result in injury.
  • Page 19 (3) using the repeat cable tie (1), otherwise vibration from the sewing machine may cause the cords become disconnected, which can cause problems with the <Securing> operation of the control box. Cords <Closing the cover> 2110M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 20: Other Cords

    (4). (The green and yellow wire is the ground wire.) 2. Insert plug into properly-grounded AC power supply. <Single-phase> <Three-phase> NOTE: extension cords, otherwise machine operation problems may result. Green and yellow wire (ground wire) 2891M T-8421B, 8422B, 8452B, 8722B, 8752B...
  • Page 21 4. Ground wire (1) Ground wire (2) Screw [With washer] (3) Screw Ground symbol NOTE: Always be sure to connect the ground wire (1), otherwise problems may occur with sewing machine operation. Oil pan 2892M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 22: Test Operation (Operating The Treadle)

    4. If the treadle (4) is pressed to position (D), (thread trimming is carried out for models with thread trimmer) and the needle rises above the needle plate and stops. 2117M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • 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 2894M <T-8452B, 8752B> Long groove 3125M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • 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. 2896M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 25: Winding The Lower Thread

    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-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 26: Installing The Bobbin

    There is an anti-spin spring (6) inside the rotary hook. The anti-spin spring (6) prevents the bobbin from racing at times such as during thread trimming. y Use bobbins (1) made of light alloy as specified by BROTHER. 2901M T-8421B, 8422B, 8452B, 8722B, 8752B...
  • Page 27 There is an anti-spin spring (10) inside the rotary hook. The anti-spin spring (10) prevents the bobbin from racing at times such as during thread trimming. y Use bobbins (1) made of light alloy as specified by BROTHER. 2904M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • 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-8421B, 8422B, 8452B, 8722B, 8752B...
  • Page 29 The thread can be passed securely in between the tension discs. Pass the thread on the inside of the tab (3). 3910M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 30: Adjusting The Stitch Length

    4-8. Using the thread wiper (Models with thread trimmer only) Press the thread wiper switch (1) to the side. 2909M After thread trimming is carried out, the thread wiper (2) will pull up the thread. 2209M 2910M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 31: Corner Sewing Method (T-8452B, 8752B)

    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 40° and a stitch length of 2.9 mm, the number of stitches becomes 6. T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 32: Using The Operation Panel (Basic Operations)

    (0í99) in the A, B, C and D stitch number displays is sewn continuously. The sewing machine sews a single cycle of A, B, C and D, and for models with thread trimmer, the thread is trimmed automatically. 2142M T-8421B, 8422B, 8452B, 8722B, 8752B...
  • Page 33 These keys are used to set the initial value for the lower thread counter. (Refer to p.29.) 2155M (17) RESET key This key is used to return the lower thread counter to its initial value and to cancel warning conditions. (Refer to p.29.) 2156M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 34: Sewing Start And End Backtack Stitches

    • For models with thread trimmer, if the indicator of the thread trimming lock key is illuminated, the sewing machine will stop in the needle up position without thread trimming being carried out. 2160M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 35: Sewing Fixed Stitches

    • If changing the number of end backtack stitches in C and D, press the fixed stitch key to temporarily turn off the fixed stitch function before making the change. (The CD display will show the number of stitches and the setting can then be changed.) T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 36: Using The Lower Thread Counter

    If you press the RESET key (2), the warning icon (1) will disappear and sewing will be possible when the treadle is depressed. y If you press and hold the RESET key (2) for 2 seconds or more, the display will return to the initial value. T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 37: Using The Operation Panel (Advanced Operations)

    • When the needle up icon (23) is illuminated, the needle bar stops in the up position. • When the needle down icon (24) is illuminated, the needle bar stops in the down position. 2207M 2208M 2174M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 38: Adjusting The Needle Up Stop Position

    Once the settings have been reset, “iniT ALL” appears in the display and the operation panel settings are reset to their factory default settings. Once the above display appears, normal operation will then be possible. T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 39: Sewing

    The power indicator (2) and (3) will illuminate. 4. Use the operating panel to carry out the programming which is necessary for sewing. (Refer to the chapter on “5. using the operating panel”.) 5. Depress the treadle to start sewing. 2893M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 40: Backtacking

    2917M <Actuator rotation function> The actuator can be rotated 90 degrees as shown in the illustration. Select the position (A or B) that is easier to use. 2918M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 41: Sewing Condensed Stitches

    (2) is being pressed.) * To stop sewing condense stitches and return to using the backtack function, lower the stopper (6) so that it does not touch the reverse stitching lever plate (7). 2921M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 42: 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-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 43: 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-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 44: Adjusting The Presser Foot Floating Amount (Minute Lifting Amount)

    If the tension of the pretension (1) is increased, the lengths of the threads trailing from the needle tips will be Longer Shorter reduced; if the tension is reduced, the lengths will be increased. Adjust by turning the pretension (1). Trailing thread 2926M 2927M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 45: Adjusting The Thread Take-Up Amount

    When sewing with a stitch length of 2 mm or less When sewing under any of the above three conditions and you would like to prevent skipped stitches, thread 2929M tightening problems such as looping, or thread breakages T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 46: Cleaning

    1. Replace the needle if it is bent or if the tip is broken. 2. Check that the upper threads have been threaded correctly. (Refer to page 22.) 3. Carry out a test sewing. 2932M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 47: Lubricating Via The Oil Cover (Every 6 Months)

    Pour lubricating oil into the oil cover (1) about as often as grease is applied. Use only the lubricating oil <NIPPON OIL CORPORATION Sewing Lube 10N; VG10> specified by Brother. 2190M * If this type of lubricating oil is difficult to obtain, the recommended oil to use is <Exxon Mobil Essotex SM10;...

  • Page 48: Applying Grease - When "Greaseup" Appears (Semi Dry Specifications)

    If this happens, apply grease and carry out the reset procedure. * If you continue to use the sewing machine after carrying out the reset procedure but without applying grease, problems with the sewing machine may result. T-8421B, 8422B, 8452B, 8722B, 8752B...
  • Page 49 When using the grease again, remove any old grease from inside the nozzle first. (Store the tube away carefully once the tube has been opened, otherwise the grease remaining inside the tube may deteriorate, and this may affect its lubricating performance.) 2937M T-8421B, 8422B, 8452B, 8722B, 8752B...
  • Page 50 (1) will change to stitch number display mode. 7. Depress the treadle to run the sewing machine for 1 second or more. 8. Turn the power switch to “OFF”. (This completes the reset 2940M procedure.) 2139M T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 51: 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 2943M machine has been used for approximately two hours. T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 52: 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-8421B, 8422B, 8452B, 8722B, 8752B...
  • Page 53 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 2944M 2946M T-8421B, 8422B, 8452B, 8722B, 8752B...
  • Page 54 Attach the anti-spin spring. 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? 19-20 Use only bobbins which are specified by Brother.
  • Page 55 0469M y Is the power supply connector Machine does not operate when power is turned on disconnected from the control and treadle is pressed. box? Insert connector securely. 2952M T-8421B, 8422B, 8452B, 8722B, 8752B...
  • Page 56 Insert connector securely. 3154M y This display is to notify you that it is time to apply grease. “GREASEUP” flashes on the operation panel when Apply grease. the power is turned on. T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 57: Error Code Displays

    Is the motor connector disconnected from the control box? (Motor lock) Insert the connector securely. y Has the machine locked up? Turn off the power and then turn the machine pulley by hand and check that it turns easily. 2202M T-8421B, 8422B, 8452B, 8722B, 8752B...
  • Page 58 Check the resistances of the solenoids. overcurrent) y Problem with control P.C. board. Replace the control box. y Is connector CN5 inside the motor disconnected? Insert the connector securely. (Problem with motor over- heating sensor) 3116M T-8421B, 8422B, 8452B, 8722B, 8752B...
  • Page 59 The settings in “Setting method for standard depression stroke” may be incorrect. Redo the settings in “Setting method for standard depression stroke”. (Treadle pedal y Problem with treadle unit. position error) Replace the treadle unit. T-8421B, 8422B, 8452B, 8722B, 8752B...
  • Page 60 (diP SW4) Set DIP switch No.4 to OFF. 3160M If an error code that is not listed above appears or if carrying out the specified remedy does not solve the problem, contact the place of purchase. T-8421B, 8422B, 8452B, 8722B, 8752B...

  • Page 61: Instruction Manual

    INSTRUCTION MANUAL http://www.brother.com/ T-8421B, 8422B, 8452B , 8722B, 8752B SA2698-601 2008.06.B (1)

This manual is also suitable for:

T-8722bT-8422bT-8452bT-8752b

Table of Contents