Doesn't anybody use arc welding any more?

[ACE HIGH]

Enoch,with arc welding,keep all gaps to 25 thous or less,this is easy to achieve and you will become a very good fitter real fast if you keep to that standard,also bevel each join where possible to 50%.
Use 2.5 mm (14 swg) rods or smaller,usually general purpose say GP 6012 or similar.
If possible try to get some 2mm (if available),shop around,they used to be sold under the names of mirrorcraft/satincraft.
If its possible to rotate the chassis for final welding,(a rotating engine stand for each end will speed up the build ) then you can with general purpose rods use the vertical down technique and produce very high quality welds,you will surprise yourself how neat they will be.Use your left hand to steady the rod as you come down.
And this applies to ALL welding and gas cutting(especially gas cutting)ont hold your breath welding,common mistake,learn to relax and breath normally.
Final finishing,remove ALL slag,tidy up with a disc grinder and round the sharp weld edges with a 1/4 or 5/16 chainsaw file these larger saw files are not generally stocked by chainsaw dealers so a 3/16 will do OK.
AND AGAIN! 25 thous,the approx thickness of a hacksaw blade is the max gap to have on all types of fit ups on these thin sections,it will soon become 2nd nature to achieve and will stop you from trying with MIG or Arc to fill gaps due to sloppy workmanship.
Arc welding is cheap,fast and very strong on these tubes once you learn how.
Give it a go!David

[ACE HIGH]

When you use the vertical down technique come down at 30/45 degrees.David

[ACE HIGH]

Landlocked,try 2.5 mm at 90/110 amps,and see if you can get 2mm.
I would not weld these thin tubes with 3mm.
I have done 1mm panel steel with 14/16 guage rods years ago.
Has any one had any experience with alloy arc welding rods?
they are being sold over here as "allyarc",I have never tried them but when next in town will buy some if they are not for DC welders ,mine are AC.David

[Land Locked]

David, I have 2mm, 2.5mm and 3.15mm in stock as they're all freely available here. (6013)

My foray into the 3mm rod on 1.6 wall material was accidental as in I only had 3mm rods on site and was so close to finished that I refused to drive anywhere at all to get thinner ones. I was surprised at how easy it was to make good hole free welds. I do however agree that one should go down to 2.5 or 2mm. My only concern being not quite the penetration I wanted with the thin rods and bumping the current up just made holes.

The ally rods are good but you MUST get the weld area cleaner than clean. I really can't stress the prep enough.

Regards
Johan

[Enoch]

Thanks David and Johan, appreciate your input. I bought a big load of 2.5mm rods that are the business, they start and maintain the arc really well. I bought the welder from a car boot sale, it has some rods with it but they were really tricky to use, I nearly gave up. Then I thought if I bought a big load of rods that were all the same it would make learning a lot easier. I bought a big bix of scrap steel of thicknesses from about 1.5mm up to about 4mm and set about practicing. First couple of sessions were an absolute disaster but then I started getting the hang of it. Best thing I did was get rid of the hand held face shield and bought one of those automatic helmets, it made so much difference and so much easier to strike the arc. It's variable so you can set it so you get a better view of the weld pool. I will practice a bit more before I start the chassis, just so I go in to it with ahigh level of confidence.
Thanks again folks, happy building

[ACE HIGH]

Thanks Enoch and Johan.Johan will try the alloy rods.
Some more tips;
If you have an air compressor buy a needle scaler,looks like a pistol with about 12 x 3mm high tensile rods makes a hell of a noise and rattles away getting rid of slag real quick,a miracle in the corners of say angle iron at (90) degrees,will be real useful for MIG welding also as it gets into the corners for getting rid of rust ,great tool ,about $100 NZ.
And while you are at it get an air riveter,great tools,about $100 NZ for a Chinese one,I would pay extra for a name brand about $200 NZ.
And also a Bosch top of the line jigsaw with genuine Bosch blades,then you will never need a gas set again except for!;
next purchase! A LPG propane gas set around $500 NZ with a BBQ bottle $45 NZ (much cheaper if you allready have a gas set,just buy tips)from your local big box shop,you will never need to hire another bottle.
Now I know I have just spent a lot of your money for you,
BUT you never paid $2000 NZ to buy a quality MIG set,no need to shag around with bottles and hireage and cost of gas and you now have some good tools to really speed things along.
Arc welding these tubes will always be strong enough,your main problem will be blowing through,you will soon sense when this will happen,your auto helmet will allow you to stop/start and the weld will look a bit like a oxy/acetelene weld if its not one of your best efforts,so,grind/wire brush it and go over(vertical down again ) to tidy it up.
Always start the rod on the earth and immediately go straight to the work so you start up with a "hot rod",also learn the technique of "starting both ends and meeting in the middle',and avoiding burning out the ends when finishing(common MIG fault also.)
Now time to rattle the bags of popcorn!!! (Stir,stir)
MIGs main advantage is that unskilled workers could be employed to mass produce cheap high volume products that could be sold quickly before the shiny paint fell off and the warranty ran out.
The above comment IS NOT directed at those on this Forum or anywhere else who run quality reputable businesses,MIG is clearly the best system for you to use.
Try building a 30/40 foot yacht/launch out in the rain and wind with MIG,you will soon find that old fashioned arc welding is not so obsolete after all.
And for the member who is using the "globular transfer method at home",probably not a good idea to hold your breath using that technique as you may well implode and blow your brains out! Dont try that at home folks! David

[Enoch]

Thanks again chap!! I have a fairly well equipped workshop including 2 lathes, milling machine, band saw, welder, bench vice, air compressor with various tools, measuring kit etc. A mate of mine has a very large pipe bender that will manage the roll bar, only thing I don't have access to is a guilotine and a sheet bender. I might well get a needle scaler, I didn't think of that. By starting the rod on the earth I assume you mean building some carbon on the end of the rod? I have found this makes it a hell of a lot easier to strike, new rods are that little bit harder.
That's an intersting technique of starting at the ends, when I was learning I found that every time I got to the end of a weld it would burn a bit of the edge away. I kind of got round it by being careful to not over run and to pull back a bit at the end of the run. Your technique sounds better to me so thanks for that.
God, I'm glad I found this place

[ozzy1]

We use 16TC (2.5mm) rods at work on anything from 1.5mm upwards with no problems and this is usually structural stuff as its a minesite,really its just about getting the amps correct and practising on the same material as what you will be welding.

[ACE HIGH]

Enoch,google sheet benders they are easy to make ,there will be plans on the net,use diy,homebuilt,and the yanks often use the term "homebrew" for diy.like ozzie says ,in the end it comes down to practice.
The main reason for starting the arc with a hot rod is that with practice you will start in the exact position real quick and make a neat job.Dont forget to use a gloved left hand to hold the rod about 40/50 mm from the arc end when it suits you ,eg vertical down.
A guillotine may be expensive and hard to make,the bosch jigsaw may well substitute,if you find a site for a homemade guillotine let us all know!They are very expensive to buy.
Also,not widely known but there is a small electric tool called a carpet cutter,has a roller on it,it will cut light alloy sheet very well indeed.These are not expensive if you can find one these days.Mine is a Black and Decker.

No I would not be without my needle scaler,its a real bonus,worth every cent! David

[Bonzo]

I must agree, sick weldding still has a place in the right eviroment.

Shipyard or perhaps in the field where shielding the weld area from the eliments is either impossible or impractable

Ark welding is more tolerant of rust, paint & other impuritys, as any shipyard or plant repairer will tell you.

That said, my local dry dock ( Former employee ) is now making extensive use of mig welders for general repairs.
When I was last working there in the late 80's, they didn't have a single mig welder
Mind you one of the last dry docks in the country to be using rivets

Back to the subject of stick welding.

difficult slag removal can somtimes be an indication of weld undercut. This occurs when the edges of the weld bead penetrates the parent metal too deeply & leave a small crater. ( Main culprits are too many amps or poor technique ).
Under cut is very undesireable & is seen as a structural weakness

The slag more often than not will peel off as the weld cools, choice of electrode also makes a difference.
The slag on some non-rutile electrodes can be a real pain to remove.

When you strike an arc do it a couple of centimetres upwind of the direction that you are intending to go, when the arc has fully established slowly move to your start point. don't worry about splatter, the welding arc will soon burn that out of the way. This way, you will eliminate the risk of slag inclusion at the weld start point.

Yes, at the end of the weld, just draw back a couple of mm & pause for a second or so, that'll fill the crater at the end of the weld . Not needed if you are simply changing for a new electode.