Sweiss SKYARC ULTRA 3140 User manual

INTRODUCTION
I
ISO9001:2000
2012 ． 09
SKYARC ULTRA 3140
Inverter DC MMA Arc Welding Machine
IMPORTANT: Read this Owner’s Manual Completely before attempting to use this
equipment. Save this manual and keep it handy for quick reference. Pay particular
attention to the safety instructions we have provided for your protection. Contact your
distributor if you do not fully understand this manual.
OPERATORS’ MANUAL

INTRODUCTION
II
CONTENT
1 SAFETY......................................................................................................................................... 1
§1.1 S IGNAL E XPLANATION .....................................................................................................................................................1
§1.2 A RC W ELDING D AMAGE .................................................................................................................................................1
§1.3 T HE KNOWLEDGE OF E LECTRIC AND M AGNETIC F IELDS ...............................................................................................4
2 SUMMARY.................................................................................................................................... 6
§2.1 B RIEF I NTRODUCTION .....................................................................................................................................................6
§2.2 W ORKING P RINCIPLE .......................................................................................................................................................
§2.3 V OLT -A MPERE C HARACTERISTIC ....................................................................................................................................
3 INSTALLATION & ADJUSTMENT .................................................................................................. 7
3.1 PARAMETERS............................................................................................................................ 7
§3.2 D UTY CYCLE & O VER HEAT .............................................................................................................................................8
§3.3 W ELDING POLARITY CONNECTION WAY .........................................................................................................................9
§3.3.1 MMA ............................................................................................................................................................. 9
§3.3.2 TIG ............................................................................................................................................................... 10
4 OPERATION CONTROL AND CONNECTORS .............................................................................. 11
§4.1 L AYOUT FOR FRONT & REAR PANEL ............................................................................................................................. 11
§4.2 W ELDING CURRENT ADJUSTMENT ............................................................................................................................... 13
§4.3 W ELDING OPERATION .................................................................................................................................................. 13
§4.3.1 Striking arc way ........................................................................................................................................ 13
§4.3.2 Manipulation of electro e ..................................................................................................................... 14
§4.4 W ELDING PARAMETERS ................................................................................................................................................ 14
§4.4.1 Joint form in MMA ................................................................................................................................... 14
§4.4.2 Electro e selection ................................................................................................................................... 14
§4.5 A RC W ELDING D EFECT AND P REVENT M ETHOD ....................................................................................................... 15
§4.6 O PERATION E NVIRONMENT ......................................................................................................................................... 16
§4. O PERATION N OTICES ................................................................................................................................................ 16
5 MAINTENANCE & TROUBLESHOOTING .................................................................................... 16
§5.1 M AINTENANCE ............................................................................................................................................................. 16
§5.2 T ROUBLESHOOTING ...................................................................................................................................................... 1
§5.3 E LECTRICAL PRINCIPLE DRAWING ................................................................................................................................ 20

CONTENT
III

SAFETY
1
1 SAFETY
1.1 Signal Explanation
 The above signals mean warning! Notice! Running parts and getting an electric shock or
thermal parts will take damage for your body or others. The corresponding notices are as
follows. It is quite a safe operation after taking several necessary protection measures.
1.2 Arc Welding Damage
 The following signals and word explanations are to some damages for your body or others
happening on the welding operation. While seeing these, please remind of yourself or others
to be dangerous.
 Only ones who are trained professionally can install, debug, operate, maintain and repair
the equipment.
 During the operation, non-concerned people should be lift, especially for children.
 After shut off the machine power, please maintain and examine the equipment according to
§5 because of the DC voltage existing in the electrolytic capacitors.
ELECTRIC SHOCK CAN KILL.
 Never touch electrical parts.
 Wear dry, hole-free gloves and clothes to insulate yourself.
 Insulate yourself from work and ground using dry insulation. Make certain the insulation is
large enough to cover your full area of physical contact with work and ground.
 Take carefully when using the equipment in small place, falling-off and wet circumstance.
 Never close the machine power before installation and adjustment.
 Ensure to install the equipment correctly and ground the work or metal to be welded to a
good electrical (earth) ground according to the operation manual.
The electrode and work (or ground) circuits are electrically “hot” when the welder is on. Do
not touch these “hot” parts with your bare skin or wet clothing. Wear dry, hole-free gloves to

SAFETY
2
insulate hands.
 In semiautomatic or automatic wire welding, the electrode, electrode reel, welding head,
nozzle or semiautomatic welding gun are also electrically “hot”.
 Always be sure the work cable makes a good electrical connection with the metal being
welded The connection should be as close as possible to the area being welded.
Maintain the electrode holder, work clamp, welding cable and welding machine in good,
safe operating condition. Replace damaged insulation.
 Never dip the electrode in water for cooling.
 Never simultaneously touch electrically “hot” parts of electrode holders connected to two
welders because voltage between the two can be the total of the open circuit voltage of
both welders.
 When working above floor level, use a safety belt to protect yourself from a fall should you
get a shock.
FUMES AND GASES CAN BE DANGEROUS.
 Welding may produce fumes and gases hazardous to health. Avoid breathing these fumes
and gases. When welding, keep your head out of the fume. Use enough ventilation and/or
exhaust at the arc to keep fumes and gases away from the breathing zone. When welding
with electrodes which require special ventilation such as stainless or hard facing or on lead or
cadmium plated steel and other metals or coatings which produce highly toxic fumes, keep
exposure as low as possible and below Threshold Limit Values using local exhaust or
mechanical ventilation. In confined spaces or in some circumstances, outdoors, a respirator
may be required. Additional precautions are also required when welding on galvanized steel.
 Do not weld in locations near chlorinated hydrocarbon vapors coming from degreasing,
cleaning or spraying operations. The heat and rays of the arc can react with solvent vapors to
form phosgene, a highly toxic gas, and other irritating products.
 Shielding gases used for arc welding can displace air and cause injury or death. Always use
enough ventilation, especially in confined areas, to insure breathing air is safe.
 Read and understand the manufacturer’s instructions for this equipment and the
consumables to be used, including the material safety data sheet and follow your employer’s
safety practices.

SAFETY
3
ARC RAYS CAN BURN.
 Use a shield with the proper filter and cover plates to protect your eyes from sparks and the
rays of the arc when welding or observing open arc welding.
 Use suitable clothing made from durable flame-resistant material to protect your skin and
that of your helpers from the arc rays.
 Protect other nearby personnel with suitable, non-flammable screening and /or warn them
not to watch the arc nor expose themselves to the arc rays or to hot spatter or metal.
SELF-PROTECTION
 Keep all equipment safety guards, covers and devices in position and in good repair. Keep
hands, hair, clothing and tools away from V-belts, gears, fans and all other moving parts when
starting, operating or repairing equipment.
 Do not put your hands near the engine fan. Do not attempt to override the governor or idler
by pushing on the throttle control rods while the engine is running .
DO NOT adds the fuel near an open flame welding arc or when the
engine is running. Stop the engine and allow it to cool before refueling to prevent spilled fuel
from vaporizing on contact with hot engine parts and igniting. Do not spill fuel when filling
tank. If fuel is spilled, wipe it up and do not start engine until fumes have been eliminated.
WELDING SPARKS can cause fire or explosion.
 Remove fire hazards from the welding area. If this is not possible, cover them to prevent the
welding sparks from starting a fire. Remember that welding sparks and hot materials from
welding can easily go through small cracks and openings to adjacent areas. Avoid welding
near hydraulic lines. Have a fire extinguisher readily available.
 Where compressed gases are to be used at the job site, special precautions should be used
to prevent hazardous situation.
 When not welding, make certain no part of the electrode circuit is touching the work or
ground. Accidental contact can cause overheating and create a fire hazard.
 Do not heat, cut or weld tanks, drums or containers until the proper steps have been taken
to insure that such procedures will not cause flammable or toxic vapors from substances

SAFETY
4
inside. They can cause an explosion even though they have been “cleaned”.
 Vent hollow castings or containers before heating, cutting or welding. They may explode.
 Sparks and spatter are thrown from the welding arc. Wear oil free protective garments such
as leather gloves, heavy shirt, cuff less trousers, high shoes and a cap over your hair. Wear ear
plugs when welding out of position or in confined places. Always wear safety glasses with side
shields when in a welding area.
 Connect the work cable to the work as close to the welding area as practical. Work cables
connected to the building framework or other locations away from the welding area increase
the possibility of the welding current passing through lifting chains, crane cables or other
alternate circuits. This can create fire hazards or overheat lifting chains or cables until they fail.
Rotating parts may be dangerous.
 Use only compressed gas cylinders containing the correct shielding gas for the process used
and properly operating regulators designed for the gas and pressure used. All hoses, fittings,
etc. should be suitable for the application and maintained in good condition.
 Always keep cylinders in an upright position securely chained to an undercarriage or fixed
support.
 Cylinders should be located:
-Away from areas where they may be struck or subjected to physical damage.
-A safe distance from arc welding or cutting operations and any other source of heat,
sparks, or flame.
 Never allow the electrode, electrode holder or any other electrically “hot” parts to touch a
cylinder.
 Keep your head and face away from the cylinder valve outlet when opening the cylinder
valve.
 Valve protection caps should always be in place and hand tight except when the cylinder is
in use or connected for use.
1.3 The knowledge of Electric and Magnetic Fields
Electric current flowing through any conductor causes localized Electric and Magnetic
Fields (EMF). The discuss on the effect of EMF is ongoing all the world. Up to now, no material
evidences show that EMF may have effects on health. However, the research on damage of

SAFETY
5
EMF is still ongoing. Before any conclusion, we should minimize exposure to EMF as few as
possible.
In order to minimize EMF, we should use the following procedures:
 Route the electrode and work cables together – Secure them with tape when possible.
 All cables should be put away and far from the operator.
 Never coil the power cable around your body.
 Make sure welding machine and power cable to be far away from the operator as far as
possible according to the actual circumstance.
 Connect the work cable to the workpiece as close as possible to the area being welded.
 The people with heart-pacemaker should be away from the welding arc.

SUMMARY
6
2 Summary
This operation manual is suitable for the models of SKYARC ULTRA 3140 | ULTRA POWER |
2.1 Brief Introduction
SKYARC ULTRA 3140 | ULTRA POWER | welders are general MMA arc welder which adopts
the latest pulse width modulation (PWM) technology and the insulated gate bipolar transistor
(IGBT) power module. It can change work frequency to medium frequency so as to replace
the traditional hulking work frequency transformer with the cabinet medium frequency
transformer. Thus, it is characterized with portable, small size, low consumption and etc.
SKYARC ULTRA 3140 | ULTRA POWER | have excellent performances: constant current
output makes welding arc more stable; fast dynamic response speed reduces the impact from
the arc length fluctuation to the current; accurate step less current adjustment and
pre-setting function. There are also some automatic protection functions for under voltage,
over current, over heat, etc. inside the welders, when the problems listed before occurred, the
alarm on the front panel is light and at the same time the output current will be cut off. It can
self-protect and prolong the using life and greatly improved the reliability and practicability
of the welders.
SKYARC ULTRA 3140 | ULTRA POWER | welders can also realize TIG operation. While MMA
operation, if the electrode touches workpiece over two seconds, the welding current will drop
to the minimum current automatically to protect the electrode. While TIG operation, the
minimum current will be outputted firstly until the arc is ignited by lifting method, the output
current will rise to the preset value, which can protect the electrode. At the same time, the arc
force and hot start will be provided with MMA operation.
SKYARC ULTRA 3140 Characteristics:
Input voltage from 110~440±15%(1~3)
Anti-sticking, Arc force, hot start, adjustable arc length
MCU control system and IGBT technology
Current preset and real-time display
Fan on demand
MMA/Lift TIG,VRD selectable
Intelligent protection: Over-voltage, Low-voltage, Over-current, Over-heat

SUMMARY
7
Protected & compatible POWER GENERATOR
No single phase de-rating
PFC/ZVS technology, Power factor more than 0.98 Compact light weight, portable,
high efficiency, Low input current
MMA——Manual Metal Arc welding;
PWM——Pulse-Width Modulation;
IGBT——Insulation Gate Bipolar Transistor;
TIG——Tungsten Inert Gas welding.
2.2 Working Principle
The working principle of SKYARC ULTRA 3140 | ULTRA POWER |welder is shown as the
following figure. Single phase 208V － 460V±10% work frequency (50/60 Hz) AC is rectified into
DC, three phase 208V － 460V±10% work frequency (50/60 Hz) AC is rectified into DC, then by
PFC circuit, DC(about 50V)is converted to medium frequency AC (about 20KHz) by inverter
device (IGBT module), after reducing voltage by medium transformer (the main transformer)
and rectified by medium frequency rectifier (fast recovery diodes), and is outputted by
inductance filtering. The circuit adopts current feedback control technology to insure current
output stably. Meanwhile, the welding current parameter can be adjusted continuously and
steplessly to meet with the requirements of welding craft.
PFC Inverter
Medium
frequency
transformer
Medium
frequency
rectify
Hall device
Current positive-
feedback control
Single-phase AC DC
AC DCAC DC
Rectify
208-460V 50/60Hz
208-460V 50/60Hz
Three-phase AC
2.3 Volt-Ampere Characteristic
SKYARC ULTRA 3140 welders have excellent volt-ampere characteristic, seeing the following
graph. In MMA welding, the relation between the rated loading voltage U
2
and welding
current I
2
is as follows:

SUMMARY
8
When I
2
≤600A，U
2
＝20＋0.04 I
2
（V）；When I
2
＞600A，U
2
＝44（V） .
64
44
20
0 600 I
2
（ A ）
U
2
（ V ）
Working
point
Volt-ampere characteristic
The relation of the rated loading
voltage&welding current

INSTALLATION AND ADJUSTMENT
7
3 Installation & Adjustment
3.1 Parameters
Model
SKYARC ULTRA 3140
Power Supply
Voltage(V) 1~110/208/220/230/240±10% 1~380/400/440/460±10% 3~220/230/240±10% 3~380/400/440/460±10%
Frequency(Hz) 50/60 50/60 50/60 50/60
TIG MMA TIG MMA TIG MMA TIG MMA
Rated input
Power （ KW ） 6.25 8.9 9.3 8.9 9.3 8.9 12.8
Rated input
Current(A) 28.4 31.8 23.4 24. 23.4 24. 13.5 19.5
Effective
Current(A) 15.5 15.9 15.3 15.6 15.3 15.6 8.9 10.6
Duty Cycle(
40
℃
10min)
30%250A
60%1 A
100%140A
30%/200A
60%/130A
100%/100A
40%/315A
60%/26 A
100%/20 A
40%/250A
60%/204A
100%/158A
40%/315A
60%/26 A
100%/20 A
40%/250A
60%/204A
100%/158A
45%/315A
60%/26 A
100%/20 A
40%/315A
60%/223A
100%/1 3A
No Load
Voltage(V) 0/15(VRD)
Welding Current
Range(A) 5~200 5~200 5~315 5~250 5~315 5~250 5~315 5~315
Efficiency(%) ≥80% ≥80% ≥80% ≥80%
Power Factor 0.98 0.98 0..9 0.9
Electrode
diameter
￠ 2.5, ￠ 3.2, ￠ 5 ,etc.
Electrode Type 6010
、 6011 、 6013 、 018 、 etc.
Net Weight(Kg) 21.8
Dimensions(mm) 535×235×435
Protection Class IP23S
Insulation Class F
Cooling AF
Note: T he above parameters are subject to change with the improvement of machines.

INSTALLATION AND ADJUSTMENT
8
3.2 Duty cycle & Over heat
The letter “X” stands for duty cycle, which is defined as the proportion of the time that a
machine can work continuously within a certain time (10 minutes). The rated duty cycle
means the proportion of the time that a machine can work continuously within 10 minutes
when it outputs the rated welding current.
The relation between the duty cycle “X” and the output welding current “I” is shown as the
following figure.
If the welder is over-heat, the IGBT over-heat rotection unit inside it will output an
instruction to cut output welding current, and brighten the over-heat pilot lamp on the front
panel. At this time, the machine should be relaxed for 15 minutes to cool the fan. When
operating the machine again, the welding output current or the duty cycle should be
reduced.
I （ A ）
0
100 ％
140 250
XThe relation between duty cycle and
welding current for G M-3150
60%
30%
Input: single phase 220V TIG
177 I
（ A ）
0
100 ％
100 200
XThe relation between duty cycle and
welding current for G M-3150
60%
25%
Input: single phase 220V MM A
130
I （ A ）
0
100 ％
158 250
XThe relation between duty cycle and
welding current for G M-3150
60%
40%
Input: single phase 380V MM A
204
I （ A ）
0
100 ％
207 315
XThe relation between duty cycle and
welding current for G M-3150
60%
43%
Input: single phase 380V TIG
267

INSTALLATION AND ADJUSTMENT
9
I （ A ）
0
100 ％
207 315
XThe relation betw een duty cycle and
welding current for G M-3150
60%
43%
Input: three phase 220V TIG
267
§3.3 Welding polarity connection way
3.3.1 MMA
workpiece
Welding holder
electrode
DCEP
workpiece
electrode
DCEN
Welding holder
SKYARC SKYARC
Choosing the connection of DCEN or DCEP is based on the arc stable burning condition. The different
electrodes need different connection way. Please refer to the electrode manual.
I （ A ）
0
100 ％
158 250
XThe relation between duty cycle and
welding current for G M-3150
60%
40%
Input: three phase 220V MMA
204
I （ A ）
0
100 ％
207 315
XThe relation between duty cycle and
welding current for G M-3150
60%
43%
Input: three phase 380V TIG
267 I
（ A ）
0
100 ％
173 315
XThe relation between duty cycle and
welding current for G M-3150
60%
30%
Input: three phase 380V MMA
223

INSTALLATION AND ADJUSTMENT
10
3.3.2 TIG
Ar
Workpiece
DCEN
Welding gun
SKYARC
2 ～ 4mm
1、 Place the welding
gun aslant.
2、 Scrape the electrode
with the workpiece.
3、 Lift arc.
Steps of scraping arc
Stricking arc of TIG operation：when tungsten electrode touches the workpiece，the
short-circuit current is only 28A . After generating arc, current can rise to the setting welding
current.If the tungesten electrode touches the workpiece when welding, the current will drop
to 5A within 2s, which can reduce the tungsten spoilage farthestly，prolong the using life of
the tungsten electrode，and prevent tungsten clipping.
●When TIG operation,
the shielded gas is inputted
to welding gun directly, and
the method of lifting arc is
scraping arc.

OPERATION CONTROL AND CONNECTORS
11
4 Operation control and connectors
4.1 Layout for front & rear panel
TIG
S c h w e i s s t e c h n i k
SWEISSWELD.COM
A
SKYARC 3140
ULTRA
A
MMA
OFF
200 A
250 A
315 A
ON
Imax
108 - 440V / 1ph & 3ph
315 AMP
108-440V
1ph & 3ph
1 Welding current display The welding current display shows the welding current now.
2 Maximum current pilot lamp This pilot lamp when lit
indicates that the maximum current is 200A.
3 Maximum current pilot lamp This pilot lamp when lit
indicates that the maximum current is 250A.
4 Maximum current pilot lamp This pilot lamp when lit
indicates that the maximum current is 315A.
Power Supply Voltage(V) Imax (A)
MMA
1~220
200
1~380/3~220 250
3~380 315
TIG
1~220 250
1~380/3~220 315
3~380 315

OPERATION CONTROL AND CONNECTORS
12
5~6 VRD pilot lamp
Choose the switch as shown below to choose VRD model.
Model Condition
Choose “1”
MMA
No load
“on” turn on
“off” turn off
Welding
“on” turn off
“off” turn on
TIG No load/Welding
“on” turn on
“off” turn off
Choose “on” MMA/TIG No load/Welding “on”/“off” turn off
Power pilot lamp This pilot lamp when lit indicates that the machine is
on.
8 Alarm pilot lamp When the machine less voltage, over current, or over
heat, This pilot lamp indicates when lit that the protection of the machine has been
activated.
9~12 Rod electrode welding key
Parameter Setting range
Arc force 0-10
Hot start 1-10
Arc length 1-10
13 Conversion switch Choose TIG .
14 Connector The welder’s positive polarity output.

OPERATION CONTROL AND CONNECTORS
13
15 Welding current regulation Set welding current.
16 Connector The welder’s negative polarity output.
1 Power source input To connect power source.
18 Power switch Choose “ON”, power through; Choose “OFF”, power cut
off.
4.2 Welding current adjustment
SKYARC ULTRA 3140 welder has the function of welding
current pre-setting. Before welding, adjusting welding
current, the welding current display will show the ampere.
It is convenient to set parameters and adjust accurately.
4.3 Welding operation
4.3.1 Striking arc way
Knocking arc: take the electrode upright to touch the workpiece, after forming
short circuit, quickly lift up about 2~4 mm, and arc will be ignited. This method
is difficult to master. But in the welding for the brittle or hard steel, it is better
to use knocking way.
electrode
workpiece
electrode electrode
workpiece workpiece
Take the electrode upright The Electrode touch the workpiece Lift up for about 2-4mm
upright
up
touch
2 ～ 4mm
Lifting arc: take the electrode to scrape the workpiece for striking arc. But it
may cause the arc scratch, so must to lift arc in the groove.

OPERATION CONTROL AND CONNECTORS
14
4.3.2 Manipulation of electrode
In MMA welding, there are three motions to being matched in the end of
electrode: the electrode moving to the
molten pool along axes; the electrode
swing right and left; the electrode moving
along welding way.
The operator can choose the
manipulation of electrode based on
welding joint shape, welding position, electrode spec, welding current and
operation skill, etc.
The details please refer to《Welding Dictionary》P69, Volume 1 of Edition 2.
§ 4.4 Welding parameters
4.4.1 Joint form in MMA
In MMA welding, the common basic joint form: butt joint, lap joint, corner joint
& T joint.
4.4.2 Electrode selection
The electrode diameter selection is based on the workpiece thickness, welding
position, joint form, welding layer, etc. Please refer to the following table.
The welding current reference for different electrode diameter
Electrode
diameter/mm 1.6 2.0 2.5 3.2
Welding current/A 25
～ 40 40 ～ 60 50 ～ 80 100 ～ 130
The relation between the welding current(I)’ factor(K) & electrode diameter(d) (I ＝ K×d: Carbon electrode)
Electrode
diameter/mm 1.6 2
～ 2.5 3.2
butt joint lap jointcorner joint T joint
electrode
workpiece
weld
1
2
3
2
1-electrode moving; 2-the electrode swing right & left; 3-the electrode move along weld

OPERATION CONTROL AND CONNECTORS
15
Factor/K 20
～ 25 25 ～ 30 30 ～ 40
Notice: the above parameters originate from《Welding Dictionary》P66～P6 ,
Volume 1 of Edition 2.
Electrode should be drying according to user manual before using. For
reducing the hydrogen of the molten pool and welding seam, and avoiding
the blowhole and cold crack.
In the welding process, the arc must not be too long; otherwise, it will cause
unstable arc burning, large spatter, light penetration, undercut, blowhole, etc.
If the arc is too short, it will cause electrode stick.
In MMA welding the arc length is usually equal to 0.5~1.0 time of the electrode
diameter. The basic electrode’s arc length is not beyond the electrode diameter,
it’s better to choose the short arc welding; the acid electrode’s arc length is
equal to the electrode diameter.
§ 4.5 Arc Welding Defect and Prevent Method
Defect name Caused reasons Prevent methods
Welding
seam
doesn’t
meet the
requirement
The groove angle is not proper
The root face and assembly gap is not equal
Welding technics parameters are
unreasonable
The welder’s operation skill is lower
Choosing the proper groove angle & assembly
gap, improve the assembly quality
Choosing the proper welding parameters
Improve the operation skill of welders
Undercut
Over current
Arc length is too long
The electrode angle is wrong
Manipulation of electrode is not proper
Choosing the proper welding current & speed
The arc can’t be drawn too long
The electrode angle should be proper
Manipulation of electrode should be correct
Incomplete
penetration
The groove angle or gap is too small, the root
face is too big
Welding parameters are not suitable, or the
assembly is not good
The welder’s operation skill is lower
Correctly to choose and process the groove
size
Correctly to assemble and ensure clearance
Choosing the suitable welding current & speed
Improve the operation skill of welders
Incomplete
fusion
The welding thermal input is too low
The arc direction is lean
There are rust & dust on the side of groove
The slag between the layers is not cleared
well
Correctly to choose the welding parameters
Operation seriously
Enhance the clearness of layers
Overlap The temperature of molten pool is too high
The liquid metal concretes slowly
Choosing parameters based on the welding
different position
Strictly to control the molten hole size
Crater The crater time lasts too short
Over current in the welding of thin plate
In the crater, electrode should be stayed for a
short time or round to manipulate electrode
after the molten pool is filled in by metal, take
to the side for crater
Blowhole
There are some dust like oil, rust or water on
the work piece surface and groove
The coating of electrode is damped& is not
Clear out the dust around groove for about
20 ～ 30mm