Nelson NS20A Instructions for use

NS20A & NS20N
Heavy Duty Floating Lift
Welding Guns
Instruction and
Maintenance Manual
ersion 1.30
December 2008
Manual Part Number 729-110-024

NS20A and NS20N HEAVY DUTY FLOATING LIFT WELD GUN
LIMITED WARRANTY
Nelson’s only wa anty is that goods being sold will be f ee f om defects in wo kmanship and
mate ial. This wa anty is exp essly in lieu of othe wa anties, exp essed o implied and whethe
statuto y o othe wise, including any implied wa anty of me chantability o fitness fo a
pa ticula pu pose.
Nelson’s liability fo b each of wa anty shall a ise only upon etu n of the defective goods at
Buye ’s expense afte notice to Nelson of the claimed b each, and shall be limited to fu nishing a
like quantity of such goods f ee f om such defects o , at Nelson’s option, to efunding the
pu chase p ice (less easonable dep eciation based on actual use); p ovided, howeve , that Nelson
will not accept eceipt of equipment etu ned unless buye has p eviously affo ded Nelson’s
pe sonnel a easonable oppo tunity to inspect and epai said equipment at buye ’s facility o
such othe location as is mutually ag eeable. Notice to Nelson must be given within 30 days of
such defect o failu e and within ninety (90) days f om the date the equipment was delive ed. No
compensation o eimbu sement fo t anspo tation costs of any kind will be allowed.
Please note that this wa anty does not extend beyond the o iginal egiste ed pu chase , and does
not wa ant equipment that has been modified by any pa ty othe than Nelson, o equipment that
has been imp ope ly installed, imp ope ly ope ated, o misused based upon indust y standa ds, o
equipment which has not had easonable and necessa y maintenance, o equipment which has
been used fo ope ation outside of specifications fo the equipment. Nelson shall neve be liable
fo consequential damages.
Nelson ese ves the ight to make enginee ing and/o pa t changes, at any time without notice, as
a esult of ou commitment to continuous imp ovement.

NS20A & NS20N Heavy Duty Gun Page 1 Revision 1.20 2/19/08
MANUAL CONTENTS
Gun Part Number
751-535-000 751-535-100 751-535-500 751-693-000
Control Cable Connector Cannon R&S Hubbell Hubbell
Weld Cable Connector CamLok CamLok CamLok Dinse
Note: All these guns a e equipped with a steel T anquil-A c
®
Plunge Dampene
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
isual Inspection................................................................................................................................................................6
Physical Inspection ............................................................................................................................................................6
SEQUENCE OF OPERATIONS ...........................................................................................................................................7
Exploded iew ...................................................................................................................................................................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 2 Revision 1.20 2/19/08
GUN SETUP FOR WELDING STEEL STUDS
Accessory Installat on
1. Inse t chuck fo 1” o smalle studs into the
chuck adapto . While holding the gun by the
chuck adapte , lightly tap the chuck with a
hamme until it is seated and held fi mly in the
tape of the chuck adapte (Figure 1). Chucks
fo studs la ge than 1” diamete sc ew onto the
½-20 th ead of the hex shaft adapte .
Note: A diffe ent Chuck is equi ed fo each
stud diamete .
2. Inse t Fe ule G ip into Foot and secu e with
setsc ews p ovided (Figure 1).
3. Inse t stud in Chuck and Fe ule in Fe ule G ip
o Fe ule Holde .
4. Loosen the sc ews holding the foot to the leg
and adjust the foot so that stud is cente ed in
the fe ule. This is important because imp ope
welds will esult if the e is binding o f iction
between the stud and fe ule. Tighten the
sc ews and echeck the cente ing.
Hex Shaft
Adaptor
Chu k
Adaptor
Chu k
Foot Ferrule
Grip
Leg
Sets rews
Leg Plunge
1/8" - 1/4"
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
fe ule (Figure 1).
2. When plunge is adjusted, tighten the leg sc ews
so that the Foot Assembly cannot move.
Note: It is necessa y to adjust plunge when
changing stud lengths.
Free Travel Adjustment
With the f ee t avel adjustment sleeve sc ewed
fully in, (clockwise) the e will be 1/16” of f ee
t avel. To inc ease the f ee t avel, back out
(counte -clockwise) the f ee t avel adjustment
sleeve. Each complete full tu n p ovides .071” of
additional f ee t avel (Figure 2).
Free travel adjusting sleeve
(plunge dampener)
Front of gun has been removed for clarity
Figure 2: Lo ation of free travel sleeve
Note: A 1/2” open-end w ench is the p ope tool
fo adjusting the f ee t avel.
Fo studs with a weld base of ½”
diamete o unde : 1/8 tu n
Fo studs with a weld base of 5/8”
to ¾” diamete : ½ - ¾ tu ns
La ge diamete studs can tole ate inc eased f ee
t avel.
These ecommendations a e fo no mal stud
welding applications. Fo special applications such
as Weld-Th u Deck, obtain app op iate application
sheet.

NS20A & NS20N Heavy Duty Gun Page 3 Revision 1.20 2/19/08
LIFT AND LIFT ADJUSTMENT
L ft Adjustment
The gun lift can be checked without welding a stud.
The ecommended p ocedu e fo checking the lift
is unde a simulated welding condition as desc ibed
below fo :
Nelweld Powe Sou ces
Se ies 6000 (TR-2400)
Se ies 5000 (TR-1600)
Se ies 4800
Se ies 3000 (NS-20A HD)
Figure 3: Rear view of gun
Nelweld Power Sources
1. Load stud and fe ule into gun with p ope
plunge setting fo welding.
2. T igge the gun in the ai away f om the wo k
su face and continue p essing the gun t igge .
Afte the gun lifts and plunges, place the gun in
no mal welding position on a piece of wood o
othe insulated type su face o on the wo k
su face and continue holding the gun t igge .
Afte a sho t delay (the default setting is two
seconds – efe to the Nelweld Manual fo
inst uctions on how to change this time, if
desi ed), the gun will lift a second time without
an a c being established. The gun will stay
lifted fo a sho t time (the default setting is two
seconds – efe to the Nelweld Manual fo
inst uctions on how to change this time, if
desi ed).
3. Measu e the inwa d movement of the shaft
extension. This is the actual lift that will occu
unde the welding condition.
Note: T igge ing the gun in the ai away f om the
wo k su face will cause the gun to lift. The lift in
open ai will be g eate than when the gun is in the
actual o simulated weld condition.
To Change L ft:
Remove ea cap on gun, loosen lock sc ew and
position the adjustable co e as equi ed (Figure 3).
To Increase L ft, sc ew out (counte -clockwise)
the adjustable co e.
To Decrease L ft, sc ew in (clockwise) the
adjustable co e.
Afte p ope lift is obtained, lock adjustable co e in
position by tightening lock sc ew. Replace ea cap
on gun.
Recommended L ft Sett ngs for Steel Studs
When weld ng:
½” diamete studs o less.................................1/16”
⅝” and ¾” diamete studs ...............................3/32”
⅞” diamete studs and ove .................7/64” to 1/8”
Core s rew
Ba k of gun
Lo king
s rew

NS20A & NS20N Heavy Duty Gun Page 4 Revision 1.20 2/19/08
LIFT AND LIFT ADJUSTMENTS
Ser es 4800 & Ser es 5000 (TR-1600)
1. Load stud and fe ule into gun with p ope
plunge setting fo welding.
2. Set weld time at app oximately ½ second. Tu n
“Lift Check” featu e ON.
3. Place gun in no mal welding position on a
piece of wood o othe insulated type su face.
4. Dep ess t igge button as if to weld.
5. Measu e the inwa d movement of the shaft
extension. This is the actual lift unde the
welding condition. Tu n “Lift Check” featu e
OFF.
Note: T igge ing the gun in the ai away f om the
wo k su face will cause the gun to lift. The lift in
open ai will be g eate than when the gun is in the
actual o simulated weld condition.
To Change L ft:
Remove ea cap on gun, loosen lock sc ew and
position the adjustable co e as equi ed (See Figu e
3).
To Increase L ft, sc ew out (counte -clockwise)
the adjustable co e.
To Decrease L ft, sc ew in (clockwise) the
adjustable co e.
Afte p ope lift is obtained, lock adjustable co e in
position by tightening lock sc ew. Replace ea cap
on gun. Adjust fo p ope weld time.
Recommended L ft Sett ngs for Steel Studs
For weld ng:
½” diamete studs o less.................................1/16”
⅝” and ¾” diamete studs ...............................3/32”
Ser es 6000 (TR-2400)
1. Load stud and fe ule into gun with p ope
plunge setting fo welding.
2. Set weld time at app oximately ½ second.
3. Place gun in no mal welding position on a
piece of wood o othe insulated type su face.
4. Dep ess t igge button as if to weld.
6. Measu e the inwa d movement of the shaft
extension. This is the actual lift unde the
welding condition.
Note: T igge ing the gun in the ai away f om the
wo k su face will cause the gun to lift. The lift in
open ai will be g eate than when the gun is in the
actual o simulated weld condition.
To Change L ft:
Remove ea cap on gun, loosen lock sc ew and
position the adjustable co e as equi ed (See Figu e
3).
To Increase L ft, sc ew out (counte -clockwise)
the adjustable co e.
To Decrease L ft, sc ew in (clockwise) the
adjustable co e.
Afte p ope lift is obtained, lock adjustable co e in
position by tightening lock sc ew. Replace ea cap
on gun. Adjust fo p ope weld time.
Recommended L ft Sett ngs for Steel Studs
For weld ng:
½” diamete studs o less.................................1/16”
⅝” and ¾” diamete studs ...............................3/32”
⅞” diamete studs and ove .................7/64” to 1/8”

NS20A & NS20N Heavy Duty Gun Page 5 Revision 1.20 2/19/08
LIFT AND LIFT ADJUSTMENTS
Ser es 3000 (NS-20A HD)
1. Load stud and fe ule into gun with p ope
plunge setting fo welding.
2. Set weld time at app oximately ½ second. If
cont ol unit is equipped with a Weld Monito
Module, set 3-position switch in the "Lift
Check" position.
3. Place gun in no mal welding position on a
piece of wood o othe insulated type su face.
4. Dep ess t igge button as if to weld.
5. Measu e the inwa d movement of the shaft
extension. This is the actual lift unde the
welding condition.
Note: T igge ing the gun in the ai away f om the
wo k su face will cause the gun to lift. The lift in
open ai will be g eate than when the gun is in the
actual o simulated weld condition.
Caut on: E atic lift can be caused by low voltage;
the efo e, it is suggested that a minimum of 65
volts open ci cuit voltage be used when checking
lift o ope ating the stud welding equipment.
To Change L ft:
Remove ea cap on gun, loosen lock sc ew and
position the adjustable co e as equi ed (See Figu e
3).
To Increase L ft, sc ew out (counte -clockwise)
the adjustable co e.
To Decrease L ft, sc ew in (clockwise) the
adjustable co e.
Afte p ope lift is obtained, lock adjustable co e in
position by tightening lock sc ew. Replace ea cap
on gun. Adjust fo p ope weld time.
Recommended L ft Sett ngs for Steel Studs
For weld ng:
½” diamete studs o less.................................1/16”
⅝” and ¾” diamete studs ...............................3/32”
⅞” diamete studs and ove .................7/64” to 1/8”

NS20A & NS20N Heavy Duty Gun Page 6 Revision 1.20 2/19/08
WELD INSPECTION
V sual Inspect on
A p ope elationship between the Lift, Plunge, Time,
and Ampe age is needed to obtain good weld esults.
The length eduction o bu n-off and the weld fillet
appea ance a e dete mined by the weld settings. Visual
weld inspection consists of inte p eting the appea ance
of the weld fillet and is no mally ve y accu ate if
ce tain guidelines a e followed.
A good weld is cha acte ized by:
• Even fillet fo mation.
• A shiny, bluish hue to the fillet su face.
• A slight flow o blend of fille metal into the
base mate ial.
• Good fillet height.
• No mal length eduction o bu n-off
A cold weld, which equi es mo e time and/o
ampe age, is indicated by:
• Low fillet height.
• Incomplete fillet fo mation.
• A dull g ay cast to the fillet su face.
• St inge s of fillet metal fo ming spide legs.
• Inadequate length eduction o bu n-off.
• Fillet sits on top of the base mate ial.
A hot weld made with too much time and/o ampe age
is distinguished by:
• Excessive spatte .
• A washed-out fillet.
• Unde cutting of the stud.
• Bu n th ough the base mate ial.
Phys cal Inspect on
If, afte 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 a e as follows:
1. Bend Test - Stud to be tested shall be bent away
f om its ve tical axis 90º o until failu e. Failu e
should occu in the stud p ope , o , on thin
plate, a full stud diamete plug of base metal
should be to n out.
2. To que Test - Stud shall be to qued until a p e-
specified loading is attained o until the stud
fails o , on thin plate, a plug of the base
mate ial should tea out.
Normal Stud Weld Stud hang-up. Check
setup of gun. Refe to
page 2.
Hot weld. Check weld
setup. Refe to page 2.
Cold weld. Check weld
setup. Refe to page 2.
Figure 4: Weld inspe tion diagrams

NS20A & NS20N Heavy Duty Gun Page 7 Revision 1.20 2/19/08
SEQUENCE OF OPERATIONS
Weld ng Gun
1. Mainsp ing (1) is pa tially comp essed and
lifting od (5) slides th ough lifting ing (4)
when the gun is placed in weld position as the
plunge is taken up.
2. P essing gun t igge button ene gizes gun coil
(2).
3. The gun coil (2) pulls back the movable co e
assembly (3), causing the lifting hook of the
movable co e assembly to lock the lifting ing
(4) on the lifting od (5).
4. At the same time, the lifting ing sp ing (6) and
co e sp ing (7) a e comp essed.
5. The cocked ing locks on the lifting od, and
the movable co e assembly "lifts" o pulls back
the enti e assembly, including the chuck and
stud (Figure 6).
6. When the stud is "lifted" f om the wo k, an a c
is initiated.
7. The assembly emains "lifted" fo a p eset weld
time.
8. At the end of this time pe iod, the gun coil (2)
is de-ene gized.
9. The movable co e assembly (3) is etu ned to
no mal position by the co e sp ing (7).
10. The lifting ing (4) is uncocked by the lifting
hook and lifting ing sp ing (6).
11. The mainsp ing (1) etu ns the assembly to
no mal 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 5: Gun me hanism in normal
position
Figure 6: Gun me hanism in lifted position

NS20A & NS20N Heavy Duty Gun Page 8 Revision 1.20 2/19/08
MAINTENANCE INSTRUCTIONS
Exploded iew
Figure 7
14