Nelson NS20A, NS20N Maintenance Manual

NS20A & NS20N
Heavy Duty Floating Lift
Welding Guns

Instruction and
Maintenance Manual

Version 1.30
December 2008

Manual Part Number 729-110-024

NS20A and NS20N HEAVY DUTY FLOATING LIFT WELD GUN

LIMITED WARRANTY

Nelson’s only warranty is that goods being sold will be free from defects in workmanship and
material. This warranty is expressly in lieu of other warranties, expressed or implied and whether
statutory or otherwise, including any implied warranty of merchantability or fitness for a
particular purpose.

Nelson’s liability for breach of warranty shall arise only upon return of the defective goods at
Buyer’s expense after notice to Nelson of the claimed breach, and shall be limited to furnishing a
like quantity of such goods free from such defects or, at Nelson’s option, to refunding the
purchase price (less reasonable depreciation based on actual use); provided, however, that Nelson
will not accept receipt of equipment returned unless buyer has previously afforded Nelson’s
personnel a reasonable opportunity to inspect and repair said equipment at buyer’s facility or
such other location as is mutually agreeable. Notice to Nelson must be given within 30 days of
such defect or failure and within ninety (90) days from the date the equipment was delivered. No
compensation or reimbursement for transportation costs of any kind will be allowed.

Please note that this warranty does not extend beyond the original registered purchaser, and does
not warrant equipment that has been modified by any party other than Nelson, or equipment that
has been improperly installed, improperly operated, or misused based upon industry standards, or
equipment which has not had reasonable and necessary maintenance, or equipment which has
been used for operation outside of specifications for the equipment. Nelson shall never be liable
for consequential damages.

Nelson reserves the right to make engineering and/or part changes, at any time without notice, as
a result of our commitment to continuous improvement.

MANUAL CONTENTS

Gun Part Number
751-535-000 751-535-100 751-535-500 751-693-000
Control Cable Connector
Weld Cable Connector

Cannon R&S Hubbell Hubbell

CamLok CamLok CamLok Dinse

Note: All these guns are equipped with a steel Tranquil-Arc® Plunge Dampener

TABLE OF CONTENTS

MANUAL CONTENTS...........................................................................................................................................................1

GUN SETUP FOR WELDING STEEL STUDS .....................................................................................................................2

Accessory Installation ........................................................................................................................................................2

Plunge Adjustment.............................................................................................................................................................2

Free Travel Adjustment .....................................................................................................................................................2

Lift Adjustment ...................................................................................................................................................................3

Nelweld Power Sources .................................................................................................................................................3

Series 4800 & Series 5000 (TR-1600)...........................................................................................................................4

Series 6000 (TR-2400) ..................................................................................................................................................4

Series 3000 (NS-20A HD)..............................................................................................................................................5

WELD INSPECTION .............................................................................................................................................................6

Visual Inspection................................................................................................................................................................6

Physical Inspection ............................................................................................................................................................6

SEQUENCE OF OPERATIONS ...........................................................................................................................................7

Exploded View ...................................................................................................................................................................8

Parts List ............................................................................................................................................................................9

MAINTENANCE INSTRUCTIONS ......................................................................................................................................10

Part Number Designation ................................................................................................................................................10

Disassembly of Gun.........................................................................................................................................................11

Examination and Cleaning of Gun Parts .........................................................................................................................12

Reassembly of Gun .........................................................................................................................................................12

Installing New Control Cables -Welding Gun #751-535-000...........................................................................................13

Installing New Control Cables -Welding Gun #751-535-100...........................................................................................13

Installing New Control Cables -Welding Gun #751-535-500 & #751-693-000 ................................................................ 13

Installing New Weld Cables -All Guns .............................................................................................................................14

DIMENSIONS AND SPECIFICATIONS..............................................................................................................................15

NS20A & NS20N Heavy Duty Gun Page 1 Revision 1.20 2/19/08

GUN SETUP FOR WELDING STEEL STUDS

Accessory Installation

Free Travel Adjustment

1. Insert chuck for 1” or smaller studs into the
chuck adaptor. While holding the gun by the
chuck adapter, lightly tap the chuck with a
hammer until it is seated and held firmly in the
taper of the chuck adapter (Figure 1). Chucks
for studs larger than 1” diameter screw onto the
½-20 thread of the hex shaft adapter.

Note: A different Chuck is required for each
stud diameter.

2. Insert Ferrule Grip into Foot and secure with
setscrews provided (Figure 1).

3. Insert stud in Chuck and Ferrule in Ferrule Grip
or Ferrule Holder.

4. Loosen the screws holding the foot to the leg
and adjust the foot so that stud is centered in
the ferrule. This is important because improper
welds will result if there is binding or friction
between the stud and ferrule. Tighten the
screws and recheck the centering.

Leg

Setscrews

Hex Shaft

Adaptor

Chuck

Adaptor

Chuck

Leg

Foot

Plunge

1/8" - 1/4"

Ferrule

Grip

With the free travel adjustment sleeve screwed
fully in, (clockwise) there will be 1/16” of free
travel. To increase the free travel, back out
(counter-clockwise) the free travel adjustment
sleeve. Each complete full turn provides .071” of
additional free travel (Figure 2).

Free travel adjusting sleeve
(plunge dampener)

Front of gun has been removed for clarity

Figure 2: Location of free travel sleeve

Note: A 1/2” open-end wrench is the proper tool
for adjusting the free travel.

For studs with a weld base of ½”
diameter or under:
For studs with a weld base of 5/8”
to ¾” diameter:

1/8 turn

½ - ¾ turns

Larger diameter studs can tolerate increased free
travel.

These recommendations are for normal stud
welding applications. For special applications such
as Weld-Thru Deck, obtain appropriate application
sheet.

Figure 1: Gun assembly

Plunge Adjustment

1. Adjust the leg and foot assembly so that the
stud extends ⅛” to ¼” beyond the end of the
ferrule (Figure 1).

2. When plunge is adjusted, tighten the leg screws
so that the Foot Assembly cannot move.

Note: It is necessary to adjust plunge when
changing stud lengths.

NS20A & NS20N Heavy Duty Gun Page 2 Revision 1.20 2/19/08

LIFT AND LIFT ADJUSTMENT

Lift Adjustment

The gun lift can be checked without welding a stud.
The recommended procedure for checking the lift
is under a simulated welding condition as described
below for:

Nelweld Power Sources
Series 6000 (TR-2400)
Series 5000 (TR-1600)
Series 4800
Series 3000 (NS-20A HD)

Nelweld Power Sources

Core screw

Back of gun

Locking

screw

Figure 3: Rear view of gun

1. Load stud and ferrule into gun with proper
plunge setting for welding.

2. Trigger the gun in the air away from the work
surface and continue pressing the gun trigger.
After the gun lifts and plunges, place the gun in
normal welding position on a piece of wood or
other insulated type surface or on the work
surface and continue holding the gun trigger.
After a short delay (the default setting is two
seconds – refer to the Nelweld Manual for
instructions on how to change this time, if
desired), the gun will lift a second time without
an arc being established. The gun will stay
lifted for a short time (the default setting is two
seconds – refer to the Nelweld Manual for
instructions on how to change this time, if
desired).

3. Measure the inward movement of the shaft
extension. This is the actual lift that will occur
under the welding condition.

To Change Lift:

Remove rear cap on gun, loosen lock screw and
position the adjustable core as required (Figure 3).

To Increase Lift, screw out (counter-clockwise)
the adjustable core.
To Decrease Lift, screw in (clockwise) the
adjustable core.

After proper lift is obtained, lock adjustable core in
position by tightening lock screw. Replace rear cap
on gun.

Recommended Lift Settings for Steel Studs

When welding:

½” diameter studs or less.................................1/16”

⅝” and ¾” diameter studs ...............................3/32”

⅞” diameter studs and over .................7/64” to 1/8”

Note: Triggering the gun in the air away from the
work surface will cause the gun to lift. The lift in
open air will be greater than when the gun is in the
actual or simulated weld condition.

NS20A & NS20N Heavy Duty Gun Page 3 Revision 1.20 2/19/08

LIFT AND LIFT ADJUSTMENTS

Series 4800 & Series 5000 (TR-1600)

1. Load stud and ferrule into gun with proper
plunge setting for welding.

2. Set weld time at approximately ½ second. Turn
“Lift Check” feature ON.

3. Place gun in normal welding position on a
piece of wood or other insulated type surface.

4. Depress trigger button as if to weld.

5. Measure the inward movement of the shaft
extension. This is the actual lift under the
welding condition. Turn “Lift Check” feature
OFF.

Note: Triggering the gun in the air away from the
work surface will cause the gun to lift. The lift in
open air will be greater than when the gun is in the
actual or simulated weld condition.

Series 6000 (TR-2400)

To Change Lift:

Remove rear cap on gun, loosen lock screw and
position the adjustable core as required (See Figure

3).

To Increase Lift, screw out (counter-clockwise)
the adjustable core.

To Decrease Lift, screw in (clockwise) the
adjustable core.

After proper lift is obtained, lock adjustable core in
position by tightening lock screw. Replace rear cap
on gun. Adjust for proper weld time.

Recommended Lift Settings for Steel Studs

For welding:

½” diameter studs or less.................................1/16”

⅝” and ¾” diameter studs ...............................3/32”

1. Load stud and ferrule into gun with proper
plunge setting for welding.

2. Set weld time at approximately ½ second.

3. Place gun in normal welding position on a
piece of wood or other insulated type surface.

4. Depress trigger button as if to weld.

6. Measure the inward movement of the shaft
extension. This is the actual lift under the
welding condition.

Note: Triggering the gun in the air away from the
work surface will cause the gun to lift. The lift in
open air will be greater than when the gun is in the
actual or simulated weld condition.

To Change Lift:

Remove rear cap on gun, loosen lock screw and
position the adjustable core as required (See Figure

3).

To Increase Lift, screw out (counter-clockwise)
the adjustable core.

To Decrease Lift, screw in (clockwise) the
adjustable core.

After proper lift is obtained, lock adjustable core in
position by tightening lock screw. Replace rear cap
on gun. Adjust for proper weld time.

Recommended Lift Settings for Steel Studs

For welding:

½” diameter studs or less.................................1/16”

⅝” and ¾” diameter studs ...............................3/32”

⅞” diameter studs and over .................7/64” to 1/8”

NS20A & NS20N Heavy Duty Gun Page 4 Revision 1.20 2/19/08

LIFT AND LIFT ADJUSTMENTS

Series 3000 (NS-20A HD)

1. Load stud and ferrule into gun with proper
plunge setting for welding.

2. Set weld time at approximately ½ second. If
control unit is equipped with a Weld Monitor
Module, set 3-position switch in the "Lift
Check" position.

3. Place gun in normal welding position on a
piece of wood or other insulated type surface.

4. Depress trigger button as if to weld.

5. Measure the inward movement of the shaft
extension. This is the actual lift under the
welding condition.

Note: Triggering the gun in the air away from the
work surface will cause the gun to lift. The lift in
open air will be greater than when the gun is in the
actual or simulated weld condition.

Caution: Erratic lift can be caused by low voltage;
therefore, it is suggested that a minimum of 65
volts open circuit voltage be used when checking
lift or operating the stud welding equipment.

To Change Lift:

Remove rear cap on gun, loosen lock screw and
position the adjustable core as required (See Figure

3).

To Increase Lift, screw out (counter-clockwise)
the adjustable core.

To Decrease Lift, screw in (clockwise) the
adjustable core.

After proper lift is obtained, lock adjustable core in
position by tightening lock screw. Replace rear cap
on gun. Adjust for proper weld time.

Recommended Lift Settings for Steel Studs

For welding:

½” diameter studs or less.................................1/16”

⅝” and ¾” diameter studs ...............................3/32”

⅞” diameter studs and over .................7/64” to 1/8”

NS20A & NS20N Heavy Duty Gun Page 5 Revision 1.20 2/19/08

WELD INSPECTION

Visual Inspection

A proper relationship between the Lift, Plunge, Time,
and Amperage is needed to obtain good weld results.
The length reduction or burn-off and the weld fillet
appearance are determined by the weld settings. Visual
weld inspection consists of interpreting the appearance
of the weld fillet and is normally very accurate if
certain guidelines are followed.

A good weld is characterized by:

• Even fillet formation.

• A shiny, bluish hue to the fillet surface.

• A slight flow or blend of filler metal into the

base material.

• Good fillet height.

• Normal length reduction or burn-off

Normal Stud Weld

Stud hang-up. Check

setup of gun. Refer to
page 2.

A cold weld, which requires more time and/or
amperage, is indicated by:

• Low fillet height.

• Incomplete fillet formation.

• A dull gray cast to the fillet surface.

• Stringers of fillet metal forming spider legs.

• Inadequate length reduction or burn-off.

• Fillet sits on top of the base material.

A hot weld made with too much time and/or amperage
is distinguished by:

• Excessive spatter.

• A washed-out fillet.

• Undercutting of the stud.

• Burn through the base material.

Physical Inspection

If, after visually inspecting the welds, a questionable
weld is evident, the weld should be physically tested.
Initial weld setups should also be physically tested.
Suggested physical tests are as follows:

Hot weld. Check weld
setup. Refer to page 2.

Cold weld. Check weld
setup. Refer to page 2.

Figure 4: Weld inspection diagrams

1. Bend Test - Stud to be tested shall be bent away
from its vertical axis 90º or until failure. Failure
should occur in the stud proper, or, on thin
plate, a full stud diameter plug of base metal
should be torn out.

NS20A & NS20N Heavy Duty Gun Page 6 Revision 1.20 2/19/08

2. Torque Test - Stud shall be torqued until a pre­specified loading is attained or until the stud
fails or, on thin plate, a plug of the base
material should tear out.

SEQUENCE OF OPERATIONS

Welding Gun

1. Mainspring (1) is partially compressed and
lifting rod (5) slides through lifting ring (4)
when the gun is placed in weld position as the
plunge is taken up.

2. Pressing gun trigger button energizes gun coil
(2).

3. The gun coil (2) pulls back the movable core
assembly (3), causing the lifting hook of the
movable core assembly to lock the lifting ring
(4) on the lifting rod (5).

4. At the same time, the lifting ring spring (6) and
core spring (7) are compressed.

5. The cocked ring locks on the lifting rod, and
the movable core assembly "lifts" or pulls back
the entire assembly, including the chuck and
stud (Figure 6).

6. When the stud is "lifted" from the work, an arc
is initiated.

Figure 5: Gun mechanism in normal

position

7. The assembly remains "lifted" for a preset weld
time.

8. At the end of this time period, the gun coil (2)
is de-energized.

9. The movable core assembly (3) is returned to
normal position by the core spring (7).

10. The lifting ring (4) is uncocked by the lifting
hook and lifting ring spring (6).

11. The mainspring (1) returns the assembly to
normal position, and this action “plunges” the
molten end of the stud into a pool of molten
metal on the base plate, thus completing the
weld.

Figure 6: Gun mechanism in lifted position

NS20A & NS20N Heavy Duty Gun Page 7 Revision 1.20 2/19/08

MAINTENANCE INSTRUCTIONS

Exploded View

14

Figure 7

NS20A & NS20N Heavy Duty Gun Page 8 Revision 1.20 2/19/08

MAINTENANCE INSTRUCTIONS

Parts List

751-535-000 751-535-100 751-535-500 751-693-000

Item # Item # Item # Item # Description Part No.

1 1 1 1 Gun Body 751-535-002 1
2 2 2 2 Front Cover 751-535-006 1
3 3 3 3 Rear Cover 751-535-007 1
4 4 4 4 Dust Seal Bellows 751-535-008 1
5 5 5 5 Plunge Dampener Assembly 751-535-010 1
6 6 6 6 Gun Coil 716-041-000 1
7 7 7 7 Main Spring 526-001-191 1
8 8 8 8 O Ring 717-306-000 1

9 9 9 9 Adjustable Core 751-535-029 1
10 10 10 10 Free Travel Adjustment Sleeve 751-535-012 1
11 11 11 11 Front Coil Yoke Sleeve 751-535-013 1
12 12 12 12 Front CoiI Yoke 751-535-014 1
13 13 13 13 Lifting Rod Assembly 751-535-015 1

*13a *13a *13a *13a Shaft Extension 751-535-011 1

14 14 14 14 Rear Coil Yoke 751-535-030 1
15 15 15 15 Threaded Hex Shaft Adaptor 751-004-028 1
16 16 16 16 Handle Cover 751-535-034 1
17 17 17 17 Cover Nut 751-333-023 2
18 18 18 18 Lifting Module Assembly 751-535-025 1

18a 18a 18a 18a Lift Mech. Housing 751-535-024 1
18b 18b 18b 18b Ring-Core Spring 526-001-192 1
18c 18c 18c 18c Lifting Hook & Movable Core Assy 751-535-026 1
18d 18d 18d 18d Lifting Ring 751-535-022 1
18e 18e 18e 18e Lifting Mech. Stop 751-535-023 1
18f 18f 18f 18f Retaining Springs 717-881-003 1

19 19 19 19 Front Bearing 751-000-013 1
20 20 20 20 Wave Washer 717-844-001 1
21 21 21 21 Cable Spacer 751-004-007 1
22 22 22 22 Wire Splice 713-032-000 4
23 23 23 23 Trigger Button 751-148-016 1
24 24 24 24 Trigger Switch Actuator 751-535-038 1
25 25 25 25 Cable Support Assembly 751-535-032 1

26a 26a 26a Weld Cable Asm. -Camlok 720-075-000 1

26b Weld Cable Asm. -Dinse 720-543-000 1

27a Control Cable Asm. - Cannon 4 Wire 721-194-000 1

27b Control Cable Asm. - R & S 3 Wire 721-194-001 1
27c 27c Control Cable Asm. -Hubbell 721-215-000 1

28 28 28 28 Locking Ball 751-000-051 1

29a 29a Trigger Switch Assembly 709-028-100 1

29b 29b Trigger Switch Assembly 709-028-200 1
31 31 31 31 Chuck Adaptor 751-004-029 1
35 35 35 35 10-32 x 1/2 Binding Hd. Screw 524-001-163 1
36 36 36 36 10-32 x 3/8 Oval Hd. Screw 524-001-215 1
37 37 37 37 10-32 x 7/8 Oval Hd. Screw 524-001-216 2
38 38 38 38 8-32 x 1/4 Flat Pt. Soc. Set Screw 524-002-005 1
39 39 39 39 5/16-18 x 3/8 Flat Pt. Soc. Set Screw 524-002-011 2

* 13a is normally part of 13 but can be purchased separately.

Qty.

Required

NS20A & NS20N Heavy Duty Gun Page 9 Revision 1.20 2/19/08

MAINTENANCE INSTRUCTIONS

Part Number Designation

The Nelson Heavy Duty handgun has been designed for use with various Nelson Stud Welding Systems. The
basic construction of the gun remains the same - only the control cable and trigger switch assembly change for
proper interconnection with the control unit. The correct gun number may be determined per the following
table:

Heavy Duty

Gun Part

Number

751-535-000 751-535-100 751-535-500 751-693-000

For Use With

Control Cable

Description

Control Cable

Part Number

Control

Connector

Type

Control

Connector

Part Number

Control

Connector

Boot

Trigger

Switch

Assembly

Series 6000 (TR-2400)
Series 5000 (TR-1600)

with 4 wire control

Series 3000 (NS-20AHD)

with 3 wire control

Series 6000 (TR-2400)
Series 5000 (TR-1600)

with 2 wire control

Nelweld Power

with 2 wire Control

6 pin – 4 wire 4 pin – 3 wire 3 Pin 2-Wire 3 Pin 2-Wire

721-194-000 721-194-001 721-215-000 721-215-000

Cannon R & S Hubbell Hubbell

714-083-002 714-061-000 714-174-000 714-174-000

N/A N/A 714-174-002 714-174-002

709-028-100 709-028-100 709-028-200 709-028-200

Sources

Connector

Pin-out

Pin

1 No Connection
2 Red (To Red Coil Lead)
3 White (To Trigger)
4 Black (To Trigger)
5 Green (To Green Coil Lead)
6 No Connection

Description

NS20A & NS20N Heavy Duty Gun Page 10 Revision 1.20 2/19/08

Pin Description

X No Connection
Y Green (To Green Coil Lead)

Z Black (To Trigger)

Small

Pin

White (To Trigger)

Pin Description

Silver White
Brass Black

Center No Connection

Pin Description

Silver White
Brass Black

Center No Connection

MAINTENANCE INSTRUCTIONS

If the gun motion becomes sluggish or erratic the gun should be disassembled, cleaned, and lubricated.

Disassembly of Gun

A. Step By Step Gun Disassembly - Refer to

exploded view

1. Loosen leg set screws (39), remove foot and
leg assembly, and unscrew chuck adaptor
(31).

2. Remove cable (26) from threaded hex shaft
adaptor (15), unscrew shaft extension (13a)
from lifting rod assembly (13), and remove
dust seal bellows (4).

3. Unscrew front cover nuts (17), remove front
cover (2), plunge dampener assembly (5),
and balance of lifting rod assembly (13) as a
unit.

4. Unscrew free travel adjustment sleeve (10),
extend the piston rod of the plunge
dampener assembly (5), disengage the spool
shaped dampener rod end from hook of
lifting rod assembly (13) and remove the
plunge dampener assembly thru the front
cover (2).

5. Remove the main spring (7) and lifting
module assembly (18) from the gun body
(1).

6. Remove screw (35) and rear cover (3).
Loosen setscrew (38) and unscrew
adjustable core (9). Do not unscrew, loosen
or remove rear coil yoke (14) or gun coil
(6).

7. Disassembly of the lifting module assembly
(18) is not routinely required. If further
disassembly is necessary, consult Figure 8.
In order to disassemble the lifting module,
the internal retaining ring (18f) must be
removed from the lifting module housing
(18a). When doing this, maintain thumb
pressure on the lifting mechanism stop
(18e) to resist internal spring pressure and
then release retaining ring (18f). Slowly
release thumb pressure and note position of
the lifting mechanism stop (18e), lifting
ring (18d), lifting hook and movable core
assembly (18c) and ring-core spring (18b)
as they are removed from the lift
mechanism housing (18a).

Figure 8: Explosion diagram of Lifting Module

NS20A & NS20N Heavy Duty Gun Page 11 Revision 1.20 2/19/08

Item # Description Part Number

18a Lifting Module Housing 751-535-024
18b Ring Core Spring 526-001-192
18c Lifting Hook & Movable Core

Assembly
18d Lifting Ring 751-535-022
18e Lifting Module Stop 751-535-023
18f Internal Retaining Ring 717-881-003

751-535-026

MAINTENANCE INSTRUCTIONS

Examination and Cleaning of Gun Parts

A. The inside diameters of adjustable core screw

(9), the lifting ring (18d) and mating diameters
on the lifting rod should be carefully examined
for wear or rust. Although the lubrication
should prevent any oxidation on these surfaces,
if they reveal signs of dirt or a dull reddish
brown stain, clean and polish with a fine (600
grit or finer) abrasive paper.

Disassembly of the lifting module should not be
necessary to inspect or clean the lifting ring,
item (18d). However, if the lifting ring shows
signs of wear or excessive dirt the module may
be disassembled as described in the Gun
Disassembly Procedure (Step 7). Mark the
position of the lifting ring. When reassembling,
consult Figure 8. The lifting ring should be
rotated 180° so the lifting hook engages the
unused hole or “window” in the lifting ring to
distribute the wear evenly. This will maximize
the life of the gun.

B. Lubricate lifting rod and cable clamp assembly

(13) surfaces with a thin coat of high
temperature bearing grease, Lubrico M-24-M
(#523-001-013) or equivalent.

NOTE: Do not over-lubricate.

Reassembly of Gun

A. Step-By-Step reassembly of gun - refer to
exploded view.

1. Reassembly of lifting module assembly
(Figure 8)

Insert ring core spring (18b) into lifting
module housing (18a). Install the lifting
ring (18d) onto the lifting hook and
movable core assembly (18c) by inserting
the hook through a "window" of the lifting
ring (18d) with the flat side of the ring
towards the lifting hook and movable core
assembly.

NOTE: The lifting ring should be
reinstalled, rotated 180° from the position it
was in when removed, to distribute the wear
evenly.

Insert the assembled lifting ring and lifting
hook and movable core assembly into the
lifting module housing (18a). Place lifting
module stop (18e) in position, flat side
towards lifting ring and apply thumb
pressure depressing the lifting mechanism
into the lifting module housing. Complete
the assembly by reinstalling the internal
retaining ring (18f).

2. Replace the lifting module assembly (18)
and the main spring (7) in the gun body.

3. Reinstall the plunge dampener assembly (5)
by extending the piston rod of the plunge
dampener. Insert the plunge dampener into
front cover (2). Inspect the O-Ring (8) on
the free travel adjustment sleeve (10) and
replace if necessary. Screw the free travel
adjustment sleeve in place.

4. Inspect and replace if necessary front
bearing (19) in front cover. Install lifting
rod (13) through rear of front cover.
Engage the hook of lifting rod on the spool
of plunge dampener.

5. Reinstall the front cover (2) and lifting rod
(13) into gun inserting the lifting rod
through main spring (7) and lifting module
assembly (18). Secure front cover with
cover nuts (17).

6. Install dust seal bellows (4) over lifting rod
and screw shaft extension (13a) into lifting
rod. Torque to 20-25 ft. lbs. Install cable
onto shaft extension and secure with chuck
adaptor (31).

7. Reinstall foot and leg assembly. Adjust the
plunge, free travel, and lift.

8. Replace rear cover (3) and secure with
screw (35).

NS20A & NS20N Heavy Duty Gun Page 12 Revision 1.20 2/19/08

MAINTENANCE INSTRUCTIONS

Installing New Control Cables -Welding Gun #751-535-000

1. Remove handle cover screws (36) and (37).
Lift off handle cover (16).

2. Lift out switch assembly (29).

3. Disconnect control cable wire (27a), cut red and

Note: Connect green coil lead with insulated wire
splice (22) or solder and tape coil lead to new
control cable lead.

6. Replace switch assembly (29a) after all

green coil lead as close as possible to the wire
splice.

4. Remove cable spacer (21) from old control
cable and install on new control cable.

5. Connect new cable as follows:

Black lead to one terminal on switch.
White lead to the other terminal on switch.
Green lead to green gun coil lead.
Red lead to red gun coil lead.

Installing New Control Cables -Welding Gun #751-535-100

1. Remove handle cover screws (36) and (37).
Lift off handle cover (16).

2. Lift out switch assembly (29).

3. Disconnect control cable wire (27b), cut red

Note: Connect green coil lead with insulated wire
splice (22) or solder and tape coil lead to new
control cable lead.

6. Replace switch assembly (29a) after all

and green coil lead as close as possible to the
wire splice.

4. Remove cable spacer (21) from old control
cable and install on new control cable.

5. Connect new cable as follows:

Black lead to Red gun coil lead using splice
#713-006-000 to one terminal on switch.

White lead to the other terminal on switch.
Green lead to green gun coil lead.

connections are made. Install cable into gun
handle. Reinstall handle cover (16) and secure
with screws (36) and (37).

connections are made. Install cable into gun
handle. Reinstall handle cover (16) and secure
with screws (36) and (37).

Installing New Control Cables -Welding Gun #751-535-500 & #751-693-000

1. Remove handle cover screws (36) and (37).
Lift off handle cover (16).

2. Lift out switch assembly (29b).

3. Disconnect control cable wire (27c). Cut the
trigger lead as close as possible to the wire
splice.

4. Remove cable spacer (21) from old control
cable and install on new control cable.

NS20A & NS20N Heavy Duty Gun Page 13 Revision 1.20 2/19/08

5. Connect new cable as follows:
Black trigger lead to Black cable lead using

insulated splice (22).
White trigger lead to White cable lead using

insulated splice (22).

6. Replace switch assembly (29b) after all

connections are made. Install cable into gun
handle. Reinstall handle cover (16) and secure
with screws (36) and (37).

MAINTENANCE INSTRUCTIONS

Installing New Weld Cables -All Guns

1. Loosen leg screws (39), remove foot and leg
assembly, and unscrew chuck adapter (31).
Remove cable (26) from threaded hex shaft
adapter (15).

2. Remove handle cover screws 36 & 37. Lift off
handle cover (16).

3. Remove cable (26) and cable support assembly
(25). Disassemble cable support assembly (25)
and remove cable.

4. Install new cable into cable support assembly
allowing 12 inches of cable to extend forward
from the front face of the cable support to the
centerline of the cable lug. The end of the
Neoprene tubing is to be flush with the cable
support. Reassemble the cable support.

5. Install cable and cable support into gun handle.
Reinstall handle cover (16) and secure with
screws (36) and (37).

6. Reattach cable to threaded hex shaft adapter
(15) and secure with chuck adaptor (31).

7. Reinstall foot and leg assembly and adjust the
plunge as described in on page 2.

NS20A & NS20N Heavy Duty Gun Page 14 Revision 1.20 2/19/08

DIMENSIONS AND SPECIFICATIONS

1.25"

2.25"

1"

13"

NELSON

NELSON

NELSONNELSON

9.25"

7"

7"

Length:

(less accessories) ........................................................................................... 13”

Basic Weight:

Includes standard legs and foot plus cable loop to cable spud .......... 7 lbs. 8 oz.

Working Weight:

Includes standard legs and foot plus four (4) feet of cable from gun handle.
(Note: Four (4) foot length of cable is normally supported by the operator

when in working position)............................................................... 10 lbs. 8 oz.

Shipping Weight:

Includes standard legs and foot plus approximately 7 feet of cable with

connectors normally supplied with gun............................................ 14 lbs. 8 oz

NS20A & NS20N Heavy Duty Gun Page 15 Revision 1.20 2/19/08

STUD WELDING SAFETY PRECAUTIONS

General: Stud welding, as with any welding process, can be dangerous if the equipment is not properly installed and maintained or if the
operator does not use the process with proper safety precautions. The operator should read and understand these precautions and be
trained or experienced In the installation, operation, and maintenance procedures provided in this Nelson manual.

Electrical: Remember, electric shock can kill! Properly install and use stud welding systems in accordance with the National Electrical
Code NFPA-70 and local codes. Take the following safety precautions:

• Do not touch live electrical parts: be sure you are Insulated from same

• Be certain that the equipment is properly grounded and that all weld cables and connectors are In good condition. Inspect the

cables, connections, etc. regularly for frays, broken insulation, insulators or other electrical hazards and repair or replace them at
once.

• Do not work in wet areas or weld when you are wet.

• Wear proper clothing at all times and when gloves are necessary due to welding position, be sure that they are dry, insulated, and

have no holes.

Fire Protection: Remove all combustible or volatile materials from the work area. Although weld spatter or berries resulting from stud
welding are minimal, proper precautions should be taken when welding near or through combustible materials to be sure that sparks or
berries cannot reach and ignite them. Store and restrain gas cylinders properly. Be sure that they never become a part of an electrical
circuit and are isolated from excessive heat or welding spatter and berries. Always have fire suppression equipment available for
immediate use and know how to use it.

Vision Protection: It is recommended that eye protection be worn by the operator at all times when welding. Eye glasses with spectacle
frames equipped with Shade No.3 absorption and filter lenses and side shields are suggested. Helpers or workers within five (5) feet of a
welding operation should wear clear safety glasses with side shields. For additional Information consult ANSI Standard Z87.1.

Hearing Protection: It is recommended that proper ear protection be used when operating or working within five (5) feet of all capacitor
discharge stud welding systems. Other stud welding operations in confined environments should be evaluated for noise level and hearing
protection need. Consult OSHA standard 29 CFR, Part 1910, Subpart Q, "Welding, Cutting, and Brazing" for additional information.

Protective Clothing: The use of protective clothing is recommended. The type of protection will vary with the stud welding process,
application, weld position and stud size being welded, but flame resistant clothing, including high boots, gloves, apron, leather leggings,
etc., should be considered to protect the operator from welding spatter, arc flash and berries if required. In all cases during welding do
not wear clothing made from flammable, synthetic fabrics. For information see ANSI/AWS Z49.1, "Safety in Welding and Cutting".

Ventilation: Continuous welding in a closed area or welding and cleaning materials with paint, epoxy, galvanizing or other coatings, can
produce fumes that are unhealthy. Natural or forced ventilation in the welding area should be provided as necessary to prevent fume
accumulation. Material Safety Data Sheets (MSDS) should be supplied by the material suppliers for materials used in the welding
process and evaluated for dangerous contents that would produce toxic fumes or gasses.

Other: Keep hands, clothing, tools, feet, etc. away from the weld stud, chuck and other moving parts during the weld cycle to avoid
pinch points or electric shock.

Maintenance: Warning - Use extreme caution when servicing or troubleshooting any electrical component of the stud welding system. If
possible, turn off all power and disconnect all electrical cables and follow the manufacturer's maintenance and service procedures.
Capacitor Discharge (CD) stud welding equipment may retain a very high electrical charge in the capacitor bank even after being shut off.
Follow the manufacturers instructions for discharging or draining the capacitor bank before servicing CD equipment.

References:

• AWS pamphlet "Arc Welding Safety"

• ANSI/AWS Standard Z49 1 "Safety In Welding and Cutting"

• ANSI Standard Z87. 1 "Safe Practice for Occupation and Educational Eye and Face Protection"

• ANSI/AWS C5.4 "Recommended Practices for Stud Welding"

• OSHA Standard 29CFR. Part 1910. Subpart Q "Welding, Cutting, and Brazing”

• CSA Standard W117.2 "Code for Safety in Welding and Cutting"

• NFPA -70 National Electrical Code

Available from:
American National Standards Institute
1430 Broadway
New York, NY 10018

Available from:
Superintendent of Documents

U.S. Government Printing Office
Washington, D.C. 20402

Available from:
Canadian Standards Association
178 Rexdale Blvd.
Rexdale, Ontario M9W-1R3

Available from:
National Fire Protection Association
Batterymarch Park
Quincy, Ma. 02269

American Welding Society

-or-

550 N W LeJeune Road
Miami, FL 33135

NS20A & NS20N Heavy Duty Gun Page 16 Revision 1.20 2/19/08

Sales and Service

North America Sales Offices and Warehouses Subsidiaries International

Atlanta

1520 Pine Log Road
Suite 6
Conyers, GA 30012

Phone: [phone]

Boston

114 Union Street
Holden, MA 01520-2549

Phone: [phone]

*Chicago

9008 S. Thomas Ave.
Bridgeview, IL 60455

708.430.3770
Phone: [phone]

Fax: [phone]

*Dallas

2211 Century Center Blvd.
Suite 105
Irving, TX 75062

Phone: [phone]

800.635.9353
Fax: [phone]

Denver

4259 S. Richfield Street
Aurora, CO 80013

Phone: [phone]

**Elyria

7900 West Ridge Road
P.O. Box 4019
Elyria, OH 44036-2019

Phone: [phone]
Fax: [phone]

Houston

1617 Fountainview Dr. #51
Houston, TX 77057

Phone: [phone]

Indianapolis

17767 Sun Park Drive
Westfield, IN 46074

Phone: [phone]

Printed in USA IDD 6-01
*Warehouse
** Manufacturing Facility

Kansas City

8600 W. 95th Street
Suite 104
Overland Park, KS 66212

Phone: [phone]

*Los Angeles

20621B East Valley Blvd.
Walnut, CA 91789-2731

Phone: [phone]

800.635.9353
Fax: [phone]

Mexico

398 Huitzilihuitl
Col. Sta. Isabel Tola
Mexico, D.F. 07010

Phone: [phone]

800.635.9353
Fax: [phone]

Milwaukee

Unit LL #1
11400 W. Bluemound Road
Wauwatosa, WI 53226-4049

Phone: [phone]

Nashville

2114 Rogers Lane
Lebanon, TN 37087-7382

Phone: [phone]

*Philadelphia

260 Boot Road
Downingtown, PA 19335

Phone: [phone]

800.635.9353
Fax: [phone]

Pittsburgh

5213 Broadlea Drive
Pittsburgh, PA 15236-2606

Phone: [phone]

Richmond

2907 Semmes Avenue
Richmond, VA 23225

Phone: [phone]

*

San Francisco

23765 Foley Street
Hayward, CA 94545

Phone: [phone]

800.635.9353
Fax: [phone]

Seattle – Export

406 – 26th Avenue Place
Milton, WA 98354

Phone: [phone]
Fax: [phone]

Tampa – Export

P.O. Box 3990
Seminole, FL 33775

Phone: [phone]
Fax: [phone]

Tampa – US

9401 Ayleshire Place
Riverview, FL 33569

Phone: [phone]

*Toronto

6199A Danville Road
Mississauga, Ontario
Canada L5T 2H7

Phone: [phone]

800.635.9353

905.795.8275

Tulsa

6104 East 32nd Street
Suite 100
Tulsa, OK 74135

Phone: [phone]

Warren

52 Casale Dr., Street
Warren, NJ 07059

Phone: [phone]

Winston-Salem

P.O. Box 5339
Winston-Salem, NC 27113

Phone: [phone]

England

Nelson U.K. Ltd.
47-49 Edison Road
Rabans Lane Ind’l Estate
Aylesbury HP19 8TE, UK

Phone: [phone]
Fax: [phone]

France

Nelson Frances S.A.S.
Z. 1 du Chemin Vert
8 rue de l’Angoumois
F-95100 Argenteuil, France

Phone: [phone]
Fax: [phone]

Germany

Nelson Germany
Mailing Address
Postfach 40 20
58272 Gevelsberg
Germany

Shipping Address

Flurstrasse 7-19
58285 Gevelsberg
Germany

Phone: [phone]
Fax: [phone]

Italy

Nelson Italy
Via Miraflores, 20
Nichelino, (TO) I-10042
Italy

Phone: [phone]
Fax: [phone]

Middle East &
Asia/Pacific

7900 West Ridge Road
P.O. Box 4019
Elyria, OH 44036-2019

Phone: [phone]
Fax: [phone]

Central & South America

P.O. Box 3990
Seminole, FL 33775 USA

Phone: [phone]
Fax: [phone]

For Distributors in specific
Areas call: 440.329.0400

General Offices

7900 West Ridge Road
P.O. Box 4019
Elyria, OH 44036-2019

Phone: [phone]
Fax: [phone]

World Wide Web

www.NelsonStudWelding.com

E-mail

[e-mail]

NS20A & NS20N Heavy Duty Gun Page 17 Revision 1.20 2/19/08