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Minerva Boskovice 4280i-6 Instructions For Service Manual

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Summary of Contents for Minerva Boskovice 4280i-6

  • Page 2: Table Of Contents

    CONTENTS: 1. General safety instructions ............................... 1 2. Introduction ..................................1 3. Head of the sewing machine .............................. 2 3. 1 Hook and hook post ................................2 3.1.1 Description 3.1.2 Height setting of the hook 3.1.3 Setting the distance of the hook from the needle 3.1.4 Angular setting of the hook (timing) 3.1.5 Protection of the needle and of the hook point 3.1.6 Setting of the bobbin case opener...

  • Page 3: Introduction

    3.7.5 Replacement of the indented belt 3.7.6 Top roller 3.7.6.1 Selection of the top roller diameter 3.7.6.2 Forward, rearward and side setting 3.7.6.3 Setting the gear clearance and in the mounting of the top roller 3.7.6.4 Replacement of the top roller Setting the presser foot lift ..............................

  • Page 5: Head Of The Sewing Machine

    3. Head of the sewing machine 3.1 Hook and the hook post 3.1.1 Description The hook (1) is mounted on the shaft (2) and is driven by the gear (3) from the shaft (4). The shaft of the hook (2) is slidably mounted on the top, in post and, on the bottom, in a needle bearing.

  • Page 6: Angular Setting Of The Hook (Timing)

    3.1.4 Angular setting of the hook (timing) The hook is to be angularly set in such a way that the hook point (1) is opposite the needle at the moment, when the needle shifts by 2.5 mm from its bottom dead center. This corresponds to the 2O5°...
  • Page 7 ° °...

  • Page 8: Dismantling Of The Hook Post

    3.1.10 Dismantling of the hook post Caution ! Danger of injury! Switch off the main switch! Before starting the setting operation, wait until the motor stops! - Loosen only one screw (5). - Unscrew the screws (6). - Shift the post(1) in the sense of the arrows and remove it out from the machine.

  • Page 9: Side Setting Of The Needle Bar Holder)

    3.2.4 Side setting of the needle bar holder The correct position of this holder is in such case, when the needle bar is lined up with the presser-foot bar. The needle bar holder can be set as follows: Caution! Danger of injury! Switch off the main switch! Before starting the setting operation, wait until the motor stops! - Loosen the screw (1) of the pin (2).

  • Page 10: Throat Plate And Its Post

    3.3 Throat plate and its post 3.3.1 Description The throat plate (1) is always for the given stitch width of needles and universal for all respective categories of sewing (see Tab. sewing equipments - Spare parts list). In the throat plate there is mounted an exchangeable throat plate insert (2).

  • Page 11: Front And Rear Guides Of Needles

    3.4 Front and rear guides of needles 3.4.1 Description The front guide (1) and the rear guide (2) are used together for stitch widths of a tandem arrangement. With the sewing categories 300 and 400, it is possible to replace these guides by one guide (4) /the rear guide and the side guide in one guide/.

  • Page 13: Thread Tensioners And Limiter

    3.5 Thread tensioners and limiter 3.5.1 Description The main tensioners (1) serve for producing the thread tension when tightening stitches. The auxiliary tensioners (2) prevent the pulling out of the thread after having ended the thread trimming when removing the sewn material, when the threads are being passed through this material and when the main tensioners are relieved.

  • Page 15: Feeding Mechanism Of The Needle Feed And Of The Lower Feed Wheel

    3.6 Feeding mechanism of the needle feed and of the lower feed wheel 3.6.1 Description The feeding mechanism is formed by the leverage (1) which is driven from the main shaft through the eccentric with connection rod (2). The feeding motion is transmitted by the shaft (3) on the clutch of the bottom feed (7).

  • Page 16: Forward And Rearward Stitch Length Distribution (Fine)

    3.6.2.3b Forward and rearward stitch length distribution (fine) When setting the maximum length of the stitch, the forward and the rearward stitch length must be equal with the maximum error of ± 5 %. This setting can be done only after having set the needle bar holder in the direction of sewing (par.

  • Page 17: Lower Feed Wheel

    3.6.3 Lower feed wheel 3.6.3.1 Feeding clutches 3.6.3.1.1 Description The feeding clutch is formed by the clutch cover (1) driven from the connecting bar (2), by the clutch star (4) driven from the connecting rod (3) and by the carrier plate (5) firmly connected with the shaft (6).

  • Page 18: Setting Of The Lower Eccentric

    3.6.3.1.3 Setting of the lower eccentric The rotation of the eccentric (3) must be delayed in phase by 1/4 revolution against the rotation of the eccentric of the stitch length. This corresponds to the angle of 244° on the handwheel (1), when the setting pin (4) is put into the eccentric (3) which is in contact with the indented belt (5).
  • Page 19 ° °...

  • Page 22: Replacement Of The Indented Belt

    3.7.5 Replacement the indented belt Before replacing the indented belt, the bottom feeding shaft is to be removed. The procedure is as follows: Caution! Danger of injury! Switch off the main switch! Before starting the setting operation, wait until the motor stops! - Loosen the screw (1) of the tensioning roller (2) and loosen - Loosen the screws (3) of the pulley (4) and shift it to the left in such a way that the screws (5 and 6) of the feeding clutch...

  • Page 23: Top Roller

    3.7.6 Top roller 3.7.6.1 Selection of the top roller diameter The machine can be supplied with two types of top roller, namely with the diameter of 25 mm and with the diameter of 35 mm. The suitability of the diameter used depends on the type of sewing and on the concrete technological operation.

  • Page 24: Replacement Of The Top Roller

    3.7.6.4 Replacement of the top roller When replacing the top roller, proceed as follows: Caution! Danger of injury! Switch off the main switch! Before starting the setting operation, wait until the motor stops! - Unscrew the screw (1). - Unscrew the screw (3) with the washer (2). - Remove the driven top roller with the holder (4) from the holder (5) and from the articulated shaft (6).

  • Page 25: Bobbin Winder

    3.9 Bobbin winder 3.9.1 Description The winder (bobbin winder) winds a reserve of the hook thread. It is driven by a spring-mounted friction gear, which stops after having filled the bobbin. An ideal winding is attained with a sufficient pretension of the thread obtained on the thread guide (4) and with 1 mm under the diameter of the bobbin.

  • Page 26: Safety Clutch

    3.10 Safety clutch 3.10.1 Description The machine is provided with a safety clutch which enables the turning through of the lower belt wheel (1) on the hub of the lower shaft (2), when the hook is blocked. This blocking occurs due to the penetration of thread into the hook path. With current running, this clutch should not disengage during the normal running.

  • Page 27: Replacing The Indented Belt

    3.11.2 Replacing the indented belt To observe: in machines with Mini-stop first remove the driving toothed belt as instructed in par. 3.13. When replacing the indented belt, the mutual position of the pulleys (4 and 5) should be maintained. Caution! Danger of injury! Switch off the main switch! Before starting the setting operation, wait until the motor stops! - Remove the handwheel, the belt guard and the V-belt.

  • Page 29: Thread Trimming

    4. Thread trimming 4.1 Description of the trimming mechanism During the trimming cycle, the moving trimming knife (1), in an opportune moment, hooks up the sewing threads and pulls them in the sense of the arrow (A) against the fixed knife (2) until the threads are trimmed.

  • Page 30: Setting The Fork

    4.4 Setting the fork In the starting rest position of the trimming mechanism, when the holder (1) is in contact with the console (2), the lever (3) must be in contact with the stop (4). Caution! Danger of injury! Switch off the main switch! Before starting the setting operation, wait until the motor stops! - Shift the shaft (5), until the holder (1) strikes the bracket (2).

  • Page 31: Setting The Retaining Spring Of The Hook Thread

    4.7 Setting the retaining spring of the hook thread The retaining spring (1) holds the hook thread after having performed the trimming. It is to be set in such a way that the force necessary for pulling out the thread from the retaining spring (1) is approximately equal to the force necessary for pulling out the thread from the hook.

  • Page 34: Maintenance (Table Of Operations)

    Maintenance Caution! Danger of injury! The maintenance operations should be performed only with the machine switched off and with the motor stopped! In the following table there are given the operations which should be performed and the respective time intervals between the individual operations.

  • Page 35: Table Of Setting The Machine According To The Sewing Category

    10.2 Table of setting the machine according to the sewing category Commercial designation of the machine 4280i - 6XX - X Standard machine setting Standard sewing parameters Sewing category Seam Thick- Number Stitch Label Needle Sewing Position Width Feeder Presser Presser Thread tension Splice of hook...

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