Bernette b68 AIRLOCK User manual

User Manual

Table of Contents
2022-05 EN 50400685.00A.04 3
Table of Contents
1 IMPORTANT SAFETY INSTRUCTIONS ................. 6
Important Information ........................................ 9
2 My bernette ......................................................... 11
2.1 Machine Overview ................................................. 11
Overview - Front ......................................................... 11
Overview - Needle Area .............................................. 12
Overview - Presser Foot ............................................... 13
Overview - Looper Area .............................................. 14
Overview - Threading Area ......................................... 15
Overview - Side Panel ................................................. 16
Symbols on the Machine ............................................. 17
Default Values ............................................................ 18
2.2 Overview - Standard Accessories ............................ 19
Included Accessories ................................................... 19
Accessories behind the Threader Cover ....................... 20
Accessories Box .......................................................... 21
3 Setting Up the Machine ...................................... 22
3.1 Working Area ........................................................ 22
3.2 Connection and Switching on ................................ 22
Connecting the Machine and Foot Control ................. 22
Switching the Machine and Sewing Light On/Off ........ 22
3.3 Foot Control .......................................................... 23
Press the Foot Control ................................................ 23
3.4 Handwheel ............................................................ 23
3.5 Machine Covers ..................................................... 23
Open/Close the Threader Cover .................................. 24
Removing/Attaching the Knife Cover Insert/Coverstitch
Insert .......................................................................... 24
Removing/attaching the Coverstitch Insert for the
Slide-on Table ............................................................. 25
3.6 Spool Holder .......................................................... 26
Attaching the Spool Holder ......................................... 26
Preparing the Thread Guide ........................................ 27
Attaching the Spool Stabilizer ..................................... 27
Place the Spool Disc .................................................... 28
Using the Spool Net .................................................... 28
3.7 Presser Foot ........................................................... 28
Positioning the Presser Foot Up/Down ......................... 28
Lifting the Presser Foot Up/Down with the Knee Lifter 29
Changing the Presser Foot .......................................... 29
3.8 Needle Area ........................................................... 30
Needle Holder ............................................................. 30
Changing the Needle ................................................... 30
Positioning the Needles Up/Down ................................ 31
Threading the Needle Manually .................................... 32
3.9 Sewing Assistance ................................................... 33
Using the Thread Cutter ............................................... 33
Needle Pad ................................................................... 33
Attaching/Removing the Knee Llifter ............................ 34
Attaching/Removing the Cut-offs Bin ........................... 34
Attaching/Removing the Freearm Cover ....................... 35
Attaching/Removing the Slide-on Table ........................ 35
Attaching the Decorative Threads Guide ...................... 36
4 Sewing Start ......................................................... 37
4.1 Check before Starting to Sew ................................. 37
4.2 Selecting the Fabric ................................................. 37
4.3 Selecting the Thread ............................................... 37
Needle Thread .............................................................. 38
Looper Thread .............................................................. 38
4.4 Selecting the Needle ............................................... 39
Detect Defective Needles .............................................. 39
Needle Overview .......................................................... 40
4.5 Fixing Fabric Layers ................................................. 40
5 Selecting a Stitch .................................................. 41
5.1 Stitch Type .............................................................. 41
Overlock Stitch ............................................................. 41
Coverstitch ................................................................... 45
Chainstitch ................................................................... 46
Combostitch ................................................................ 47
5.2 Stitch Chart ............................................................ 49
6 Machine Settings ................................................. 53
6.1 Preparing the Machine for Overlock or Overlock/
Chainstitch Combo ................................................. 53
6.2 Preparing the Machine for Cover- and Chainstitch .. 53
6.3 Setting the Knife ..................................................... 53
Knife «On/Off» ............................................................ 53
Setting the Cutting Width ............................................ 54
Adjusting the Stitch Width ........................................... 55
6.4 Setting the Upper Looper On/Off ............................ 56
6.5 Upper Looper Converter Hooked in/Hooked out ..... 57
6.6 Setting the Stitch Length ......................................... 57
6.7 Rolled Hem Selection Lever «N/R» ........................... 58

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42022-05 EN 50400685.00A.04
Setting Overlocking «N» ............................................. 58
Setting Rolled Hem «R» .............................................. 58
6.8 Setting the mtc micro thread control ...................... 59
6.9 Setting the Presser Foot Pressure ............................ 60
6.10 Adjusting the Differential Feed ............................... 61
Default Value "1" ....................................................... 61
Gathering/Gather to fit "1.5 – 2" ............................... 62
Stretching "0.6" ......................................................... 63
7 Threading ............................................................. 64
7.1 Preparing for Threading ......................................... 65
7.2 Threading the Needle Thread ................................. 66
Threading the Left Overlock Needle Thread LN/Yellow 66
Threading the Right Overlock Needle Thread RN/Green
................................................................................... 67
Threading the Left Coverstitch Needle Thread LC/
Yellow ........................................................................ 68
Threading the Center Coverstitch Needle Thread CC/
Green ......................................................................... 69
Threading the Right Coverstitch Needle Thread RC/
Blue ............................................................................ 70
7.3 Threading the Looper Thread ................................. 71
Using the Air Threader ................................................ 71
Threading the Looper Thread with an Auxiliary Thread 73
Using the Threading Wire ........................................... 73
7.4 Changing the Thread ............................................. 74
Knotting Thick Thread ................................................ 74
Changing the Needle Thread ...................................... 74
Changing the Looper Thread ...................................... 75
8 Sewing Test ......................................................... 76
8.1 Perfoming a Sewing Test for an Overlock Stitch ...... 76
8.2 Perfoming a Sewing Test for an Coverstitch ........... 76
8.3 Perfoming a Sewing Test for an Chainstitch ........... 76
8.4 Optimizing Stitches ................................................ 77
4-Thread Overlock with Integrated Safety Seam .......... 77
3-Thread Super Stretch ............................................... 77
3-Thread Overlock Wide (LN) ...................................... 78
3-Thread Overlock Narrow (RN) .................................. 78
3-Thread Flatlock Wide (LN) ........................................ 79
3-Thread Flatlock Narrow (RN) .................................... 79
3-Thread Narrow Seam ............................................... 80
3-Thread Rolled Hem .................................................. 80
2-Thread Wrapped Overlock Wide (LN) ....................... 81
2-Thread Wrapped Overlock Narrow (RN) ................... 82
2-Thread Flatlock Wide (LN) ........................................ 82
2-Thread Flatlock Narrow (RN) .................................... 83
2-Thread Rolled Hem .................................................. 83
2-Thread Overlock Wide (LN) ...................................... 83
2-Thread Overlock Narrow (RN) .................................... 84
2-Thread Chainstitch .................................................... 84
3-Thread Overlock (LN) + Chainstitch (RC) .................... 85
3-Thread Overlock (RN) + Chainstitch (RC) .................... 85
2-Thread Overlock (LN) + Chainstitch (RC) .................... 86
2-Thread Overlock (RN) + Chainstitch (RC) .................... 87
4-Thread Coverstitch .................................................... 88
3-Thread Coverstitch Wide (LC-RC) .............................. 88
3-Thread Coverstitch Narrow (LC-CC) .......................... 89
3-Thread Coverstitch Narrow (CC-RC) .......................... 89
3-Thread Picotstitch ..................................................... 89
9 Practical Overlocking ........................................... 91
9.1 Securing Overlock Stitches ...................................... 91
Sewing in the Overlock Chain at the Start of the Seam . 91
Sewing in the Overlock Chain at the End of the Seam .. 91
Securing Overlock Stitches ........................................... 92
Knotting the Overlock chain ......................................... 92
9.2 Removing a Stitch ................................................... 92
9.3 Securing Coverstitches ............................................ 93
Securing Cover- and Chainstitches at the Start of the
Seam ........................................................................... 93
Securing Cover- and Chainstitches at the Seam End ..... 93
Securing the Stitches at the Seam End and Detaching
the Thread Chain ......................................................... 94
9.4 How to Undo Coverstitches .................................... 95
Undoing Coverstitches ................................................. 95
Undoing Chainstitches ................................................. 95
9.5 Sewing a Hem ........................................................ 95
9.6 Flatlock ................................................................... 96
9.7 Joining Seams ......................................................... 97
9.8 Binding Seams ........................................................ 97
9.9 Topstitching Seams ................................................. 98
9.10 Gathering ............................................................... 98
Pulling the Needle Thread ............................................ 98
9.11 Gathering a Seam ................................................... 99
9.12 Sew Outer Corners ................................................. 99
9.13 Sewing Inner Corners .............................................. 100
9.14 Sewing Inner Curves ............................................... 100
9.15 Sew Outer Curves and Circles ................................. 101
10 Appendix .............................................................. 102
10.1 Storing and Transporting the Machine .................... 102
Storing the Machine .....................................................102
Transporting the Machine ............................................102
10.2 Maintenance and Cleaning the Machine ................. 102

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2022-05 EN 50400685.00A.04 5
Cleaning the Machine ................................................. 102
Cleaning the Looper Area ........................................... 103
Cleaning the Air Threader Pipes .................................. 104
Cleaning the Suction Feet ........................................... 104
Oiling the Machine ..................................................... 104
10.3 Troubleshooting ..................................................... 105
10.4 Technical Specifications .......................................... 106

IMPORTANT SAFETY INSTRUCTIONS
62022-05 EN 50400685.00A.04
IMPORTANT SAFETY INSTRUCTIONS
Please be aware of the following basic safety instructions when using your
machine. Before using this machine, read instruction manual carefully.
DANGER
To protect against electric shock, the following instructions must be observed.
• Never leave the machine unattended when it is connected to the power
supply.
• Immediately after use and before cleaning, switch off the machine and
disconnect the power cable from the outlet.
In order to protect against injury, the following instructions must be adhered to.
• Do not look directly into the LED lamp with optical instruments
(e.g.magnifying glass).
• If the LED lamp is damaged or defective, have the LED lamp checked or
repaired at your local authorized bernette dealer.
• Switch off the machine before working in the needle area.
• Before starting the machine, attach all protection guards and close the
covers.
WARNING
To reduce the risk of burns, fire, electric shock or injury to persons, the following
instructions must be observed.
General Facts
• This machine may only be used for the purpose described in this instruction
manual.
Working Environment
• Do not use the machine outdoors.
• Only use the machine in dry rooms.
• Do not use the machine in a humid area.
• Do not use the machine in rooms where aerosol products (sprays) are being
used.
• Do not use the machine in rooms where oxygen is dispensed.
Technical Condition
• Never use the machine when it is damp.

IMPORTANT SAFETY INSTRUCTIONS
7
2022-05 EN 50400685.00A.04
• Do not use the machine if it is not working properly.
• Do not use the machine if a cable or the plug is damaged.
• Do not use the machine if it has been dropped, damaged or has fallen into
water.
• If the machine is damaged or does not work properly, have the machine
checked or repaired by your local authorized bernette dealer.
• Keep all ventilation openings of the machine and the foot control free of
lint, dust and loose cloth.
• Do not use the machine if the ventilation openings are blocked.
Accessories and Supplies
• Only use the accessories recommended by the manufacturer.
• Always use the original bernette Stitch Plate.
An incorrect stitch plate can result in needle breakage.
• Use only straight needles of good quality.
Bent or damaged needles can cause needle breakage.
• This machine is double-insulated (except for USA, Canada and Japan).
Use only identical replacement parts. See instructions for servicing of double-
insulated products.
• To lubricate the machine, only use the supplied overlocker oil.
Safety Instructions
• While operating the machine, all protective inserts must be in place and all
covers must be closed.
Appropriate Use
• The machine may be used, cleaned and maintained by children older than
eight or by people with reduced physical, sensory or mental capabilities or if
there is a lack of experience and knowledge as long as they have been given
instructions.
• Furthermore, these persons must be supervised while working with the
machine, and/or they must know the safe operation of the machine and be
aware of the resulting hazards.
• Children must not play with the machine.
• Special care should be taken when the machine is operated by or in the
presence of children.
• Only use the machine with the supplied power cable.
• USA and Canada only: Do not connect power plug NEMA 1-15 to circuits
exceeding 150 volt-to-ground.

IMPORTANT SAFETY INSTRUCTIONS
82022-05 EN 50400685.00A.04
• Only use this machine with the supplied foot control of type
4C-326G/4C-316B.
• Do not insert any objects into the openings of the machine.
• Do not place any objects on the foot control.
• While sewing, guide the fabric gently.
Pulling and pushing the fabric can cause needle breakage.
• Keep fingers away from all moving parts.
• Special care is required in the needle area, the loopers and the knife.
• For activities in the needle area - such as threading the needle, changing the
needle, threading the looper or changing the presser foot - switch off the
machine.
• To switch off, set the power switch to «0».
• When protective covers are removed, when the machine is oiled or when
other cleaning and maintenance operations mentioned in this instruction
manual are carried out, switch off the machine and disconnect the power
plug from the outlet.
• Pull the plug out of the outlet by pulling on the plug. Do not pull on the
cable.

Important Information
9
2022-05 EN 50400685.00A.04
Important Information
Availability of the Instruction Manual
The short manual is part of the machine.
• Keep the short manual of the machine in a suitable place near the machine and have it ready for
reference.
• The latest version of the detailed instruction manual can be downloaded at www.bernette.com.
• When passing on the machine to a third party, enclose the short manual of the machine.
Proper Use
Your bernette machine is conceived and designed for private household use. It answers the purpose for
overlocking fabrics as it is decribed in this instruction manual. Any other use is not considered proper.
BERNINA assumes no liability for consequences resulting from improper use.
Equipment and Scope of Delivery
Example images are used in these instructions for the purposes of illustration. The machines shown in the
images and the accessories shown therefore do not always match the actual items included with your
machine. The supplied accessory can vary depending on the country of delivery. You can acquire any
accessories mentioned or shown that are not included in the scope of delivery as optional accessories from a
specialist bernette dealer. Further accessories can be found at www.bernette.com.
For technical reasons and in order to improve the product, changes may be made to the equipment of the
machine and the scope of delivery at any time and without prior notice.
Maintenance of Double-insulated Products
In a double-insulated product two systems of insulation are provided instead of grounding. No grounding
means is provided on a doubleinsulated product, nor should a means for grounding be added to the
product. Servicing a double-insulated product requires extreme care and knowledge of the system and
should only be done by qualified service personnel. Replacement parts for a double-insulated product must
be identical to the original parts in the product. A double insulated product is marked with the words:
«Double-Insulation» or «double-insulated».
The symbol may also be marked on the product.
Environmental Protection
BERNINA International AG is committed to environmental protection. We strive to minimize the
environmental impact of our products by continuously improving product design and our technology of
manufacturing.
The machine is labeled with the symbol of the crossed-out wastebin. This means that the machine should
not be disposed of in household waste when it is no longer needed. Improper disposal can result in
dangerous substances getting into the groundwater and thus into our food chain, damaging our health.
The machine must be returned free of charge to a nearby collection point for waste electrical and electronic
equipment or to a collection point for the reuse of the machine. Information on the collection points can be
obtained from your local administration. When purchasing a new machine, the dealer is obliged to take back
the old machine free of charge and dispose of it properly.
If the machine contains personal data, you are responsible for deleting the data yourself before returning the
machine.

Important Information
10 2022-05 EN 50400685.00A.04
Explanation of Symbols
DANGER Designates a danger with a high risk which can lead to serious injuries or even death unless it is avoided.
WARNING Designates a medium-risk hazard which can lead to serious injuries if not avoided.
CAUTION Designates a low-risk hazard which can lead to minor or moderate injuries if not avoided.
NOTICE Designates a hazard which can lead to material damage if not avoided.
You will find tips from bernette sewing experts next to this symbol.

My bernette
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2022-05 EN 50400685.00A.04
2 My bernette
2.1 Machine Overview
Overview - Front
1
2
3
4
5
6
7
10
8
9
11
12
13
1 Guide Rail 8 Thread Guide Plate
2 Freearm 9 Threader Cover
3 Sewing Light 10 Thread Deflection Fingers
4 Thread Cutter 11 Coverstitch Insert
5 Presser Foot Pressure Wheel 12 Cut-offs Bin Snap-in Opening
6 Needle Thread Take-up Lever Cover 13 Connection for Knee Lifter (FHS)
7 Thread Tension Adjustment

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12 2022-05 EN 50400685.00A.04
Overview - Needle Area
1
2
4
5
3
8
7
10
9
6
1 Stitch Plate 6 Thread Guide on the Machine
2 Stitch Plate Screw 7 Thread Guide on the Needle Holder
3 Standard Presser Foot 8 Needle Holder
4 Presser Foot Release Button 9 Needle Screws
5 Presser Foot Bar 10 Needles

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2022-05 EN 50400685.00A.04
Overview - Presser Foot
1
2
3
45
6
8
10
9
7
1 Presser Foot Sole 6 Shaft Groove
2 Presser Foot Sole Pin 7 Marking: Right Overlock Needle (RN)
3 Presser Foot Spring 8 Marking: Right Coverstitch Needle (RC)
4 Fixing Screw 9 Marking: Center Coverstitch Needle (CC)
5 Presser Foot Shaft 10 Marking: Left Coverstitch Needle (LC)

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14 2022-05 EN 50400685.00A.04
Overview - Looper Area
5
2
1
4
3
9
7
10
11
8
12
6
1 Knife On/Off 7 Upper Looper
2 Cutting Width Dial 8 Lower Looper
3 mtc micro thread control dial 9 Chain Looper
4 Rolled Hem Selection Lever 10 Air Threader Pipes Upper Looper
5 Feed Dog 11 Air Threader Pipes Lower Looper
6 Knife 12 Air Threader Pipes Chain Looper

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2022-05 EN 50400685.00A.04
Overview - Threading Area
1
2
3
4
6
5
7
8
1 Threader Cover 5 Air Threader Nozzles
2 Threading Chart 6 Air Threader Lever
3 Knife Cover Insert/Coverstitch Insert 7 Accessories Stored in the Needle Threader
Cover
4 Air Threader Connector On/Off 8 Upper Looper On/Off

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16 2022-05 EN 50400685.00A.04
Overview - Side Panel
11
12
9
8
7
6
5
10
1
2
3
4
1 Carry Handle 7 Stitch Length Setting
2 Retractable Thread Guide 8 Differential Feed Dial
3 Spool Pin 9 Handwheel
4 Spool Holder 10 Air Vents
5 Needle Pad 11 Foot Control-/Power Connection
6 Presser Foot Lifter 12 Main Switch

My bernette
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2022-05 EN 50400685.00A.04
Symbols on the Machine
The symbols on the machine are for your guidance and give assistance when adjusting settings and
threading the machine.
• Overlock Stitch Formation «OL»
• Coverstitch Formation «CS»
• Chainstitch Formation «CS»
LN
(Left Overlock Needle)
Left Overlock Needle Thread
Thread Path Yellow «OL»
LC
(Left Cover Needle)
Left Coverstitch Needle Thread
Thread Path Yellow «CS»
RN
(Right Overlock Needle)
Right Overlock Needle Thread
Thread Path Green «OL»
CC
(Center Cover Needle)
Center Coverstitch Needle
Thread
Thread Path Green «CS»
RC
(Right Cover Needle)
Right Coverstitch Needle Thread
Thread Path Blue «CS»
UL
(Upper Looper)
Upper Looper Thread
Thread Path Blue
LL
(Lower Looper)
Lower Looper Thread
Thread Path Red
CL
(Chain Looper)
Chain Looper Thread
Thread Path Purple «CL»

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18 2022-05 EN 50400685.00A.04
ULC
(Upper Looper Converter)
Upper Looper Cover
Upper Looper On/Off
CW
(Cutting Width)
Cutting Width
SL
(Stitch Length)
Stitch Length
DF
(Differential Feed)
Differential Feed
N/R Rolled Hem Selection Lever
mtc mtc micro thread control
FHS
(Free Hand System)
Knee Lifter (Free Hand System)
Foot Pressure
Air Threader
Air Threader Connector On/Off
Default Values
The default values of the machine are chosen so that the settings are suitable for most typical applications.
The default values are marked on the machine with a dot.
The actual values may differ from the stitch chart depending on the fabric, thread and stitch and may need
to be adjusted to the result of the sewing sample.

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2022-05 EN 50400685.00A.04
2.2 Overview - Standard Accessories
Included Accessories
To find more accessories, visit www.bernette.com.
Figure Name Purpose
Foot Control with Power
Cable
To connect the machine with the power supply
system.
To start and stop the machine.
To control the sewing speed.
Cut-Offs Bin To collect scraps and fabric trimmings.
Knife Cover Insert To protect the fingers and to deflect the fabric cut-
offs during the sewing process.
Coverstitch Insert To protect the fingers and the looper area.
Coverstitch Insert for Slide-on
Table
To protect the fingers and the looper area.
To increase the sewing area when using the slide-
on table.
Freearm Cover To extend the work surface.
Slide-On Table To increase the sewing surface.
Free Hand System (FHS) To raise and lower the presser foot.
Standard Presser Foot For all overlock, cover and combostitches.
For general sewing projects.

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20 2022-05 EN 50400685.00A.04
Figure Name Purpose
Retractable Thread Guide For an even unwinding of the thread from the
thread cones.
Accessories Box To store the supplied accessories as well as
optional accessories.
Accessories behind the Threader Cover
The most often used accessories while sewing are stored behind the threader cover on the machine, so it is
always quickly at hand.
Figure Name Purpose
Needle Set ELx705 CF Recommended needles for all-purpose use.
Screwdriver To loosen or tighten the fixing screws on the
needle holder.
Upper Looper Cover To cover the upper looper.
For sewing 2-thread overlock and the 3-thread
super stretch stitch.
Brush To clean the feed dog and the looper area.
Tweezers For gripping the thread in tight positions.
Needle Threader/
Inserter
To manually thread, insert and remove the needle.