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'Weldert Handbook

Copyright @ 2OO7 by Richard Finch, S.A.E., A.\7'S.Cover design by Tiesa Rowe/Bird StudiosCover photos courtesy Lincoln Electric{enny OgbornEditing, Design and Production by Michael Lutfy

All rights reserved' -r., h. ""..^.r,,ccrr- ".rnnerl- or rristrihrrted i onic form withoutNo part of this book may be reproduced, scanned, or distributed in any printed pr electr

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rights. Purchase only authorized editions.HPBooks is a registered trademark of Penguin Group (USA) Inc'

First edition : Aprrl2007

ISBN: 97 8-I-55788-513-5

PRINTED IN THE I.INITED STAIES OF AMERICA

109876

NOTICE: The information in this book is true and complete to the best of our knowledge. All recommendations

on parts and procedures are made without any guarantees on the part of the author or the publisher. Thmpering

with, altering, modifying, or removing any emissions-conffol device is a violation of federal law. Author and

publisher disclaim all liability incurred in connection with the use of this information.

Wmonnis Hanoooor

It is not possible to weld thick materials with one pass.

lgl must bevet the edges as shown here, ttren wilO iwo,Ittree 0r more passes to obtain 100% weld fusion andstrength.

Simple rotatinqfixture brinoE

the weld seamio&e welder. Using

one saves a lotof time and

makes all of thewelds easy to

see and to weld.

Welding jig forfuselage ofsteel-tube

airplane: I use5/8',-thick

particle boardandnaillxl-

1/2 x 2-in. pineblocks to it tohold tubing in

place. Positionblocks about 3

in. from eachweld joint to

avoid firehazard.

pants with full--length sleeves and.legs. .il7ear gloveswhen uslng a drsc gnnder or torch.

WETDI[G JIGSA wrlding

1ig is a fixture d_.lig"d for holding

parts in position during welding. The term scaresmany would-be welderi becaus6 rhey envision avery complicated deviced.signed by a weldingengineer. This is true only ifit was desiened tJ weldhundreds of parts on a pioduction-lineiasis. Iis-welded usually means that all weldments, o, *."ld.dassemblies, come out looking exactly the same, withconsistent qqaliry For example, you should use awelding jig if you're building 1,d00 airliner sears.

For a onetime projecr, a ii[ can be as simple asVise-Grip pliers or just a pieie of angle iron used toprop up a part while it's welded in pJace. The moresophisticated welding jigcan be liki that shownabove for welding race-car frames and roll cages.

Fortunately, you probably won't have to concefnyourself with such a device. The mosr frequentlvused jiLin my welding shop is a simple three-leigedfinger. The metal finger ralies the place of yourhnger so you won'r get burned while holding a parrin place during weld'ing.

. Remembel "

ji1is whatever it takes to hold partsi, 0.i".. rlntil tacliwelding and finish-weldingLnbe done. Thck welds are a"series of very short"weldsspaced at even intervals. The tack welis hold twopieces of metal together so they can be finish-welded.

\YoodenJigs-Awooden iie is iust thar-plywood or plrticle board *itf, srirallwood blocksnailed ro it to hold meta.l pieces in place. Vhenwelding one or r*o ,.r.rntlies, sucir a simplewooden jig is sufficient. See the illustrarion below. Ihave welded airplane parrs, race-clr parrs, evenfactory production parts such as turbochargerwastFgatesr turbocharger conrrol shafts andseatheadrests on wooden ligs.

Permanent Steel Jigs*Factories use heavy steelweldlng Jrgs ro ensure consistent sizes and fit ofparts. You wouldn't wanr to buy a new exhaust

flstem for your car and discouei that the facroryhad welded the muffler inlet pipe on the wronqside, Factory welding jigs ro .r,iur. that weidefparts will be interchangeable. Even small race-carfactories have weldinsiier to assureinterchangeabiliry antr ri improve producrion rares.

\Telding jigs have their drar,nrbacks, thoueh. Forexample, when welding 4130 steel in a hea'vywelding jig, the parts s"ometimes musr be stress-reheved ro remove internal loads. The iis doesn'tallow the parrs ro twist and conform ,o &r.rr.,trom warpage. k holds the weldments in position,regardless of how they want ro move. Th&efore,

-

internal stresses deveiop in the welded assembly.These srresses must be relieved, or the part may failwhen it's put into use, or service. See tire sidebar onpage 44.

=,,1r,..iy,.,.l=

Frrrrxcarvo JrcctNc

s.0rrd

HEAT DISTORTION PULLS INTHIS DIRECTION

t{etal tends to shrink when welded. As weld bead cools,the vertical piece in this drawing is pulled toward theweld. Allow for distortion by tack-weldin$ both sides,tren welding on alternate sides as illustrated in stitch-welding, page M,

Tips for Welding With JigsAaoiding W'arpage-Study the sketches in thischapter ind you'll learn to cope with warpage inwelding, I said cope with because you cannot stopwarpage, just limit it,

\flhen building a large tubular structure such as

an airplane fuselage, I usually start welding at thefront ind work to:ward the back, alternatiig fromside to side. Even better would be to have twopeople welding symmetrically opposite sides

iimultaneously, but that is not done easily. So dothe next best thing when weldingalarge strufiure:Weld one ioint, tlien the opposite one to cancel theeffbcts of warpage from welding the first joint.

Check alignment after each pair of welds. Repeatthis welding-and-checking process until thestructure is completely welded. it would be a shameto get a frame oi fuselage B0%o complete anddiscover that it's 712" outof square. A frame,fuselage or large assembly that far out of square isscrap metal.

Ih.ch W'eld Firsr-Almost every structure shouldbe tack-welded prior to finish welding. As

mentioned; tacli welds are a series of imall weldsbetween rwo adjacent pieces. Spaced about 1 l/2"apart, they serve to ali[n the rwo pieces, hold themtogether and help prevent warpage.

'$7hen the finalbead is made, thi tack welds are remelted andbecome a part of it.

Only where the designer calls for completewelding of a joint before welding another sectionshould"you bypass the tack-weldlng rule.

Gas Wlded S*ucat res-'f/hen torch-welding

Horizontal piece warps as weld bead cools. Such warpageis normal, and can be corrected by heating andstraightening after the weld is completed. ln lhisillustation, dull red heat should be applied to the bottomof the horizontal plate to straighten it,

TOPVIEWSIDE VIEW

Example olconkollingwarpage.fromtack welding:Space tube upfrom flat plate.Make tack-weld1. Then squaretube to plate;make tack-weld2. Make tack-weld 3. Thensquare tube toplate;maketack-weld 4.Finish weld cannow be made.

an airplane fuselage or race car frame, I stress-relievethe ju'st-complerei weld by slowly pulling the torchaway from the work. I do this over a period ofabout 60 seconds. I never just finish a weld and jerkthe torch away. That would surely cause cracking.

Another way to minimize stress craclc in weldedassemblies is conrolling the air temperature in yourworkshop. Never weld in a cold or drafiy workshop.A weld ii more sensitive to cold and drastic changes

than the human body!You'll have the best resultswelding in a room temperarure of 90'F (32"C), but70-80""F (21-27"C) worla OK, too. All you'll haveto do is become accustomed to working at above-avetase room temDerature.

Doi't tryo *.li in extremely cold weather. Thechances oi qnO steel cracking ifter welding at 40"F(4"C) are 20 times greater than at 80"F (27"C).Mild steel is less prone to cracking from cold-air

Chapter 12

MIGWELDIT{G

with TIG, and it was really hard for the welding deparrmentto keep up wirh airplane production. It rook o#.rvlta.iShours to build one seat wlth TIG weldins.

, Sg y. purchased a high-quaiiry tr4iC #elding machine andhad the welders rake ceitifiiation tests with it. 1fter a week,we were ready to build certified aircraft seats. production ofseats,insrantly.we.nr

_up. One welder could build up to 4 seatsin B hours with the MIG welder. That is a400o/o increase inproducdon.

THE D0WI,|S|DEThere was one drawback, however; the MIG welds were

not as prery as the old TIG (tungsten inert gas) welds. Buttheseats allpassed Magnaflux inipection, ar,? 9 gr.r"shtesring. However, when we later tiied to weld tu6uhr ensinemounrs with MiG rather than TIG, we found that the "corrosion protecrion oil inside the engine mount tube leakedout at several places because of cold st-arts. A cold start is alack of penetration where the weld bead appears to cover aseam but is oniy.lappe4 9ug. unril the bead'prt,gresses.

MIG welding is notably less accurare thanTIG weldineand somewhar less accurate rhan arc welding. At ,ecent ricecar shows and welding trade shorrus, builderiand buyers were

l:3ld *T*..nting about the inherent lack of accuricy ofMlG-welded tubular framework as found in race .", fr*.,and aircraft frames. The problem is that the weld bead willlook good, when in factl}o/o or more of the bead is on on.

Home workshop-antique auto restorers find the Lincoln 11O-volt sp-I2s MIGwetder very,useful in making exhaust system repairs. Note that this welder islts.tlto l loldang picnic table, covered with a sheet of plywood, as a weldingtable. Gourtesy Lincotn Eleciric Go.

Ml:#t;',at*#*#J;i#ifu::,afier uncrating it. Because of this fact, MIG #jding h"sbecome extremeiy popular in recent vears.

\X/hen the first.didon of this boo(*as prinred in 19g0,MIG welders were rarher simple machines. But electronicinyentions and technological idvancemenrs revolutionizedthe welding equipment iidustry. In 1980, MIG welders wereheavy and nor very accurate. Today you c:m buy a verypowerful, accu.rte but rarher comblicated MIG weidir.

So MIC welding machines are available in many sizes andone size does nor fir all needs. You really need ro know *hrtthe welder will be used for durinq its long and useful life.Small, low-amp lvllg welders .# n.r., 6'e upgraded to doheavy work. Rither large MIG welders can beiuned andadjusted down to do lieht weldins, as well as somewharheary worl<, however, 6any of rhI hrge units cannot betuned down and slowed down ro do tf,in-wall, smalldiamerer tubing and aurobody sheet metal.

The major advantage of MIG weldine is its simpliciw andspeed. If tested besidi any stick welding" machine ior I 'hour,the MIG machine would be able to *""1d 4 to i0 rimes morethan the srick-weldine machine.

. Several years ago I #anted ro increase production rates of

alrcraft sears for a six-passenger, twin-engine airplane. Thefirsr 400 ship-sets of sears (2*,400 serrs) liad been rvelded

WrtDnR's [IeNosoor

and

NOZZLEWIRE ELECTHODE

METAL DROPLETS

lf- GASSHTELD

Small-diameter, consumable electrode-wire-is fed into weld puddle at ahigh rate, or up to 700 in. per minute (ipm). lnstead of argon shielding gastypically used with TIG welding, carbon dioxide (G0z) is prelerred for MIGweldinq. Shielding gas is not required when llux-cored-wire is used.

high-qualiry welding wire rather than the cheapestwire vbu can find. flead Chaoter 4. to learn morewire you can find. Read Chapter 4, to learn moreabout the differences in weldins rod and wires.

So, can the accuEcy problem be overcome? Yes,

n-read on. But MIG is inherently less accurate

g rod anct wlres.r be overcome? Yes, it

6xn-1s2d on. But MIG is inhethanTIG.

BASIG WIRE.FEED OPERATIOI{Here's how a wire-feed welder operates: The gun

is positioned over the weld seam at the same angleyou would hold an arc-welding rod. Cup-to-workdistance should be about equal to the distanceacross the cup opening. The gun rigger is thenpulled, activating the DC current, positivelycharged wire electrode-reverse polariry-and gas

flow. (Straight polariry is rarely used because the arcis unstable and erratic. Also, penetration is lower.)The wire is simultaneously fed through the gunnozzle and contacts the grounded base metal,causing a short circuit and resulting arc to srart.Resistance heatins melts both the base metal anResistance heating melts both thethe ends of the elictrode. The wire then melts backfaster than it is being fed to the base metal,momentarily breaking.the arc and depositing metal.The arc force flattens the molten metal.

But the wire electrode is still advancing into thepuddle, repeatedly arcing and melting offagain andagain. This on-and-offprocess occurs about 50times per second, causing rhe characteristic buzzyou hear. Some people describe a properly adjustedMIG welder as sounding like frying bacon.

MIG welding is called gets its name-metal inertgas-from the rypes of electrode and shieldingused. UnlikeTIG welding, a MIG welder uses a

consumable metal electrode. This electrode is acontinuously fed wire that exits from the center ofthe welding torch, where aTIG welder tungstenwould normally be; thus, the name wire-feed.Typical wire sizes are 0.024",0.030", 0,035" and0.045". Up to 1/16" diameter can be used with

ial equipment. CO2 shielding gas is used in

Arc starts at leftand weld beadmoves to right.

Wire contin-uously advances

and melts as itcontacts base

metal. Withmachineadjusted

correctly, cycleoccurs smootfily

and quickly,sounding as if it

were baconfrying.

member and not on the other member, making thisweld only 40o/o as strong as it should be. \7e foundthe same problem when trying t9 MIG. weld theengine mounts on twin-engine General Aviationairplanes.

WHY IESS AGGUBAGY?The most common reason is that the MIG gun

hides the weld puddle. The solution to thatproblem is to view the puddle from the side, ratherthan from behind the MIG gun.

The second reason is the bright light produced bythe MIG weld process, combined with the smokeand spatter, make the weld puddle much harder tosee than with other rypes of welding. A partialsolurion is to installa small, high-intensiryheadlight on the gun, and to weld with gas ratherthan.flux-cored u'ire. A third solution is to use

speclal equlpment. LLr2 shreldlng gas $ used rnplace of argon because CO2 is less expensive.Hollow flux-core elecrodes are used frequendy,flollow llux-core elecrodes are usect rrequenily,elimihating the need for gas shielding, but with lots

weld bead-is fast, especially when comy when compared tothe MIG welder is cleanTIG. Another advantage of the MIG welder is cle

welds-much cleaner than those possible from an

of smoke and soatter.Fast & Cteai-Themajor advantage ofwire-

feed welding is that it's fmt. Unlike arc welding orTIG welding, you rarely have to stop for a newwelding rod. Also, its weld rateinches per hour of

ll{, ll{

START ---+

arc welder, when used with gas shielding.

K

MIG'S7prnmc

Modes of MIG WeldingShort- Circuh Thansfer-was the ori gi nal

method of MIG welding. Ir still exists today in the110-volt machines and in the more basic types of220-volt machines. See rhe top drawing on page 98.

Globalar Transfer-means thar the weld wireonly rouches the metal when the weld begins. Afterthat, globs of molten wire are expelled inio thepuddle. Globular transfer occurs especidly withhigher voltage, CO2 gas and mild steel electrodes.

SprayArc Thansfer-occurs at higher amps andvolts and wire-feed speed, and with argon shieldinggas. Higher metal-deposition rares occur, and thearc gives out a higher frequenry humming sound.Spray arc transfer is desirable in the flat position.

So-CalAirgasmakes this GoldGasrM mix ofargon andoxygen for MIGwelding. Askyour gassupplier toadvise you onthe best mix touse for MIGwelding.

For MIG weldingthese specialpliers are reallyhandy to have.They cut andpull wire, cleanout nozzles,remove colletsand cups. Askyour weldingsupply dealer fora pair of tfiese.

Nozzle Dip orNozzle Spray isused in MIGwelding to makelhe inevitablespatter easier toremove lrom lhegun nozzle. AllanHancockCollege.

Pubed Spray Thansfer-is possible when using aecial weldins machine that is desisned to orovidespecial welding machine that is designed to provide

optional pulsed arc. Because the pulsed sprayoptlonil putseo arc. because tne pulsed sprayoperates at rwo hear pulses, the weld puddle is

allowed to freeze slishtlv between oulies. ThisoPerares at rwo neat pulses, tne welo prloole 1r

allowed to freeze slighrly berween pulses. Thisfeature orovides for better control of thin secrfeature provides for better control ofdrin sections,for welding aluminum, and for welding out-of-position with steel wire.

Spot lYelding-is possible with a MIG welder byadding a spor-welding timer to the machine. Andthe welder can also spot weld with short, quicktrigger pulls of the MIG gun, But this is not as

clean a method as a specific-purpose spot welder.See Chapter l5 for spot welder information.

UUIRE.FEED MACHIlIESThe MIG welder is a simple, compact welding

machine. It consists of the welding gun, powersupply, wire-drive mechanism and control unit,shielding gas supply and, for some heary-duryunits, a water cooling system.

place of theTIG torch or arc-welder stinger isa gun. The typical gun looks like a pistol anda gun. r ne ryprcar gun rooKs llKe a plsror anodirects the filler metal and shielding gas to the weld

GunIn

seam. Service lines running to the gun include anelectric-power cable, electrode conduit, and gas

hose, if used. Heavy-dury industrial-type guns alsohave water lines for water-cooling. Otherwise, guncooling is done with air. Electric power is

transferred to the wire electrode via a slidingcontact with the copper electrode guide tube in thegun.

The gun nozzle, which is usually inrerchangeable,determines the gas-shield coverage of the weldpuddle. Nozzle-orifice size varies from about 3i8"to7l8" (10 to 22mm). A larger orifice givesadditional shielding, as does alarger TIG torch cup.

Power SupplyAlmost all wire-feed weiders supply DC current.

This requires a tran.sformer-rectifier when using anAC porver source. Depending on the machine,output can range from 15 to 1200 arri-ps. Requiredpower supplies typically range from 110 to 2001230volts, or all the way up to 575 volts, depending onmachine output. Dury cycle is either 600/o or1 00%o.

Wire-Drive Mechanism & Gontrol UnitThe wire-drive mechanism is relatively simple. It

consists of a wire spool and DC motor powereddrive rolls-nvo wheels that run against each other

E

'WrtDnn's HeNosoox

A crew memherfrom Ghip Ganassi

Nextel Cup teamis welding some

new brackets thefront clip of thisrace car with a

MIG welding gun.Photo courtesyLincoln Electric

Co.

It is possible toMIG-weld alu-minum and to

weld by either gasshielding or flux

core shielding asyou need to do,

but you mustchange out the

liners in the MIGgun to make

those changes.The gun liner kiton the left is for

the smallerLincoln MIG

welding machinesthat are to use

llux-cored wire.The liner kit on

the right and thedrive roll and

tensioning clampare for vuelding

aluminum, allwith the same

Lincoln ElectricCo. MIG guns.

ffi='17;

:=

fi

with the r.vire in between. Sometimes, tlvo sets ofwheels are used. The drive-roll rnechanism pulls che

wire off the spool and pushes it through theconduit to the gun at a welder-adjusted rate.

The MIG welder control unit regulates arcstarting and stopping, as well as wire-feed, gas flowand, sometimes, water flow rates. lt a]so

synchronizes these functions. Usuallx there's ajogging feature that feeds the wire to or through thegun while not welding.

Similar to the wire-jogging feature, the controlunit also has a shielding-gas purge srvitch romanually control gas flow. In addition. timerscontrolpreweld and posrweld gas flowautomaticaliy. The purge sr.vitch can override theauromatic timers. Another timer controls waterflow, if water cooling is used. Finally, a wire-feedbrake stops the electrode the instant the gun switch

Notice the welds on this Ducati motorcycle. The weldbeads are thick and rounded, more for looks than forstrength, although you do want strong frame welds whenriding at over 150 mph! MIG welds have a unique lookthat distinguishes them from TIG or oxyacetylene welds.

is released. This prevents wire from being fed to thepuddle rvhen the arc is interrupted.

Shielding GasExcepr for CO2 used in place of argon, a fullG

welding shielding-gas setup is similar to that usedfor TTG welding. Not only is CO2 less expensivethan argon, it also has superior heat conducriviry.

Regaldless ofthe gas used, cbnstant pressure andflow must be maintained while welding. A,lso, youmust be able to adjust pressure and flow fordifferent applications. Therefore, the gas cylindermust be equipped just as if it rvere used for TIGwelding. Although different gases use diflerent flowmeters or florv gauges, the CO2 musr have irs

pressure and florv regulated.

Types of WireFeed Welders

tffhen considering a wire-feed welder, rememberthe old adage: You can't drive a raiiroad spike witha tack hammer or a tack with a sledgehammer. Youmust match the machine to the job. lf you haveboth heary and light-duty welding to do, you needrwo rvelding machines, one heaw and one light.

Check out all the MIG machines that areavailable today. Take your time in making yourdecision about which MIG machine to buy'. Thereare many options. Several MIG machines can haveadd-on modules installed so that you can also TIGweld with your MIG power suppl,v.

1l}-Voh-There are many acceptable 1 10-r,olt

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ii

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MIG'$(rrorNc

wire-feed welders available.Hobart Brothers Company makesa light-dury portable wire-feedwelder for sheet metal and bodyshop work rhat plugs into 110-volt service. This welder has somelimitations, but it's effective atdoing what it was designed for-welding 24 gauge (0.0239") sheetmetal. It willnor weid heavy-gauge srock, such as that used fortrailer hitches or farm equipment.Some of the specs for thismachine are:

. 100-amp maximum.

. 0.024" and 0.030" steel wire.

' 0.035" and smaller aluminumwire.. Gas-flow timer allows makinestitch welds-tack welds about"ll2" to I i' long-and tack welds.Timer guarantees faster gasshutoffafter eachweld is

completed.. \Wire-feed speed conrolregulates arc heat.. Unit is self-contained except forCO2 shielding gas rylinder. CO2is used instead ofargon becauseit's effective ind inexpensive..fi/here high-qualiry welds are

Jason Woods olAlamogordo, NM,leans on thefront lender ofhis friend, CoachLindley's 1969Ford Muslangthat is beingprepared forpaint after lotsof MIG ureldingbodywork. Thecar took a firstplace trophy in acar show afterthe iob wasdone.

Bay Giriza is alaser eyesurgerytechnician lor Dr.Schuster in ElPaso, TX, Healso built thiswinged supermodified racecar, using a MIGwelder t0construct thetubular frame.

required in 4730 steel, a mixtureof 75o/o CO7 and 25o/o argon may, ,*,?be used. Thii comes premixed in one cylinder from 575-Vob Heaoy-Duty Wbder-lhe minimum

these 800-amp machines will weld is 100 amps.They have a 100% dury cycie at 800 amps!You canoperate the machine at B00 amps allday, withoutcool-down, if necessary. If you have some heavy-dury welding to do, this type o[machine willhandle the job. But it's definitely not for theayerage home welder! If you think you absolutelymust haye one, try it first. Remember, you don'tneed a sledgehammer to drive tacks, and you don'tneed a 10O-amp-minimum welder to build a udlirytrailer.

MIG.WEMIilG STEEL & ATUMI}IUMMost welding instructors give you about five

minutes of discussion about a MIG-weldingmachine and then tell you to go run a few beads ona piece of steel or aluminum. And that will be theexrent of the instruction. That's how easy it is tostart wire-feed welding.

welding supply stores.

200/230 Yoh-Severa:l companies makeconventional 200 I 230 -v olt wire- feed welders. Theseare the most common machines. Most machinesthis size can be made portable, but rarely will theyplug into a wall socket. Chances are you'll have tochange the socket ro fit the plug on the machine.They can handle 0.024",0.030," 0.035" and0.045" wire.

No COt Gas Reauired Your Choice-If you usefl ,r*-.or.f, * ire-i.045" iir.n.r.r-.ro gas

shielding is required, It's similar to stick welding,except you don't have to stop for new rod. Flux ison the inside of the electrode, so it doesn't chip andflake off

'Whenwelding anykind of sheet steel, plain orgalvanized, this wire gives good weld performancewith spatter. It can also weld thicker meuls athigher volt and amp settings.

g

W'ELDr,R's flnNonoox

Properly dressedlor MIG welding,

Ron Chase olWestem Welding

Co. shows howto repair a

folding tablewith a gas-MlG

220-vollmachine. Notethat Ron's left

hand is guidingthe gun for

accuracy,

r How hot the wire gets when the volt and ampsettings are adjusted to mid-range.

' How much shielding gas is supplied to the weldpuddle when adjusted for 20 cfh.

Not onlywill one machine vary slightly fromanother, each project will vary in adjustmentrequirements. For example, if I were describing howto drive my caL I couldn't tell you how far todepress the accelerator to maintain a certain speed.It's the same with MIG welders. Although you cancome close on your initial settings, trial and errorare required to get them exactly right. So pick areasonable starting setup. Fine-tune the machineafter making a few test beads. Practice on somescrap metal pieces of the same metal you're weldinguntil you can determine the right settings.

As you find che correct settings for each weldingsituation, record them on your "\7ire-FeedAdjustment" chart on the next page. Then, nexttime you're welding 0.020" steel or whatever, youc:rn set up your machine perfectly by just referringto your chart.

Adjust by Sound-l adjust my welder bylistening to the arc. As I mentioned earlier in thischapter, when it's right, the arc sounds almost likebacon frying on a grille over an open fire. Ofcourse, you should also check for proper welddeposit and penetration. Once you're satisfied withthe arc sound and weld quality, have someone readt}re vott and amp gauges while you are welding.Record these numbers in youf chart, too.

'W'ire Cuners-Nways keep a pair of s

diaeonal cutters handv.'You'lI soon learn

Howeve! there's more to wire-feed welding thanpointing the gun at the weld seam and pulling thetrigger. Problems can occur if you don't takeprecautions. The wire may get tangled in the drivemechanism or stick in the coller. The cup on thegun may fill with spatter, making weld quaiiryerratic. Just call it Murphy's Law of MIG welding.

AdjustmentsThere are also several adiustments that have ro be

exactly right or the weld will end up looking worsethan if it were done with an E-6011 arc-weldingrod in the hands of a beginner. Here are someadjustments you'll have to make:

. \7ire-feed speed.r pqwsl-2rnp5.. CO2 or argon gas-flow rates.. \fire size.. Amps and volts while welding

You'll need a helper to monitor these readings as

you weld, and make adjustments as necessary.

PreparationBefore you start welding, attach a small notepad

or a sheet of paper to the MIG machine to recordsettings that work for you. Copy the chart on rhenext page to help record your settings, or make onesimilar.

Settings vary from one machine to another. Eventhough two machines are the same model, they arenot the same machine. Some examples of thesevariables are:

. How fmt the wire filler rod is fed at a setting of 1,

2or3.

a pair of smalldiagonal cutters handy. You' learn why.

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V/hen you pull the trigger to sart the arc and itdoesn't, you'll end up with a "pile" of wire. Eventhough the arc doesn't start, shielding-gas flow andwire feed do. You can't release the trigger fastenough to prevent this, only minimize it. Beforeyou can continue welding, you must cut off theexcess wire. Simply snip it off with cutters andcontinue welding.

Maintenance*Lack of maintenance causes

your MIG welder operating trouble-free, performthese simple maintenance operations:. Keep the cup clean. Normal weld spatter will clogthe cup quickly, blocking gas flow and thereforecause the welder to be unprotecred from air. Toprevent this, you should coat the inside of the cupwith an anti-spatter spray or gel such as Nozzle-Kleen or Nozzle-Dip Gel from Weld-Aid Products.

frequent wire-feed welding problems. The cup willset dirw-it must be keot clean. The cuo andget dirry-it must be kept . The cup and

,r resularlv. Sonozzle must be cleaned of spatter regularly. Specialsprays and iellies are made for this puroose. To keesprays and jellies are made for this purpose. To keep

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MIG'Wnromc

As a less-expensive alternative, many welders usePam, an aerosol cooking-oil substitute available atsupermarkets. If the nozzle does get dirry, clean it.Special ream-like MIG welder nozzle cleaners areavailable.. Keep the drive gears and rollers clean. Copper-piated wire will clos the drive rolls in a hurrv, so' Neep rne orrve g€ars anq roilers crean. \-oPPepiated wire will clog the drive rolls in a hurry, sopiated wlre wlll clog tne dflye rolls ln a nurry, so

avoid copper-plated wire, if at all possible. Every2-3 horrrs of weldins time. check the drive roller2-3 houri of welding time, check thefor metal filinss. and brush them awafor metal filings, a h them away before

WIRE.FEED ADJUSTNilEilT

Metal Thickness Amps Volts Gas Wire Wire(i"J Flow Size Speed

0.0200.0300.040

Make copies of chart for recording MlG-welder setups. You'llthen be able to make quick setups when doing similar jobs.

rollers

continuing. To reduce wire drag and clogging,lubricate the wire. Use a treated-felt applicatorlube steel wire; untreated applicator for alumir

contrnurng. lo reduce wlre clrag ano clogglng,lubricate the wire. Use a treared-felt aoolicator tolube steel wire; untreated applicator foi aluminumwlre.

MIG Welding Stainless SteelThe correct wire for MlG-welding stainless steel

depends on its alloy. In most cases, 3O0-series MIG-welding wire will work with the more common3OO-series stainless steel. If the alloy is unknown,try ER-308, a general purpose stainless wire. Youcan even weld mild stebl with ER-308 wire. Theweld on mild steei wiil be much less ductiie thanthe base metal. Some common stainless steel wirenumbers are ER-308, ER-309, ER-310, ER311,ER-348, ER-410, ER-420, ER-430 and ER-502.

Each number represents different carbon andalloy content. Forlnstance, the chemical content ofER-308 is carbon 0.08%, chromium 20o/o, nickel10ol0, manganese 2o/o, silicon A.50o/a, phosphorus0.A3o/o, sulfu r 0. 03ol0.

NOTE: Most high-strength steel used in late-model cars is confined to body structures,reinforcements, gussets, brackets and supports. Inmost cases, the outer panels remain regular mildsteel and can still be gas-welded or brazed.

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