Mild Steel Thickness?

[rtbcomp]

The link that Wozzah mentioned is also in the "Links" section Under Legal Stuff > Motoring & Towing.

I'll also post it Here.

My insurance company states my trailer "must comply with manufacturer's specifications" which seems to eliminate home-made trailers.

 

[GeorgeB]

Have you considered MIG? Can't be anything over 3mm on a trailer and arc really isn't the best process for anything thinner than that. MIG would be a lot easier for thinner stuff than trying to do a botch with Arc.

Here's some practice welding I did today, in an attempt to get back into the swing of arc welding thin sheet steel. This is a lap joint on 1mm sheet. It may not win any awards for artistic merit but it's fully fit for my purpose and is similar to the joints I did on the car sill to get through an MOT. Would I be likely to get a job as a professional arc welder? Hardly, but it meets my DIY needs. Is MIG welding kit likely to be easier? Almost certainly.

The images are front and rear of the same test piece.

Malcolm - how long (approx) have you spent practising the arc welding of thin sheet steel?

 

[TechnicAl]

George

is that using Aldi rods?

 

[GeorgeB]

George
is that using Aldi rods?

Yes, with Aldi 2mm for the initial tacks and 3.2mm for my poor attempt at running two continuous beads. Perhaps leading branded rods would have made life easier, plus the skill of someone who really knows how to arc weld, which I clearly don't. Nevertheless, as I said, it more than suffices for my needs and the joint seems strong enough. One spot on the right side of the reverse image looks like a blow-through but it's not. I didn't break through once. If anything, perhaps there's too little penetration.

 

[Drains]

I'm saying nothing.

 

[Dogbreath23]

"I'm saying nothing."
me niether...Can I just stick my ha'peth worth in though. In my expieriance a decent rig makes up for crappo rods more using top quality rods on a crappo rig. you could get 2.half kilos of 3.25 s in MM's for six quid I think. I would'nt touch that 50 quid welder with a barge pole mind....

 

[shenion]

I'm saying nothing.

Hehe,

1mm steel, 7014 1.6mm name brand rods (Hobart/WeldIt), Airco industrial welder, absolutely no practice first.

The right corner was after changing the range of the welder to the mid range but same current (20-220A range instead of 5-60A). Made it much easier. Holes as I did not realize the welder was set up to 220 amp start current.

The upper flat beads were after playing with settings a bit.

Still not something I consider "good enough". GeorgeB we're in completely different worlds.

With some practice, and tuning of settings and technique, could be passable welds. Still need new glasses and fighting poor near vision.

One thing about high-OCV welders, you need to break the arc quick. The Airco will hold an arc well over an inch. Pull to slow away and you blow a hole (end of run at top middle.) Longer arc = more heat on big and inverter welders; longer arc = less heat on cheap buzz boxes.

Was a fun 10 minutes to try. I'll stick with my MIG or TIG for thin stuff. Have the small rods for use with my portable arc; usually on heavier, 1.6mm and up steel.

 

[Hitch]

Rusty, i would seriously consider what you plan on doing.
You have a few hefty joints on a trailer, is this likely to be the heaviest material you plan on welding, You say you'd like to do some lighter work if possible, such as what?
The arc setup will be fine for the heavier stuff, while mig would be better suited to thinner material, but a more expensive setup.


If you end up with stick welds like George's picture above, your probably going to spend more on abrasives than you would a welder to to have done it properly in the first place.


As someone that earns my keep using welders, i wouldn't even consider picking up a stick welder for anything under 2-2.5mm unless i really had too.

 

[GeorgeB]

With some practice, and tuning of settings and technique, could be passable welds.

I agree. Your welds show promise. My contention is that you could get near-perfect arc welds on a joint like that, if you get the technique right. Perhaps your Hobart 7014 rods are better than Aldi 6013. Do you have a photo of the rear side? I also agree with Hitch that a MIG welder is the popular choice for this type of welding.

I'm starting to think that lap joints are more of a challenge than butt joints. I can get much neater results on thin sheet butt joints. The first time I tried tacking this 1mm sheet I aimed the tacks astride the top and bottom sheets, which were clamped reasonably close together. I thought it would be easy but, to my surprise, the lap joint fell apart, with almost zero adhesion to the lower sheet. I cut that bit off and tried again using a different technique. Perhaps it's because this is galvanized sheet. I need to practice more with lap joints. Here are the two sides of the failed tack welds, showing the semi-circles blown through at the edge.

 

[Wozzaaah]

George, genuine questions;
Why are there two runs with one ground down?
Am I correct in assuming the lower run was the first then you went back over it with the run you've ground down?

 

[GeorgeB]

George, genuine questions;
Why are there two runs with one ground down? Am I correct in assuming the lower run was the first then you went back over it with the run you've ground down?

Yes, I got there in the end - it's a strong enough joint - but it's a mess. I need to do more work, practicing the technique, settings and everything for lap joints.

My first attempt at a continuous seam was 'on top' of multiple tacks. I then ground that back a bit and tried to run a second seam to the side of the joint. The ground joint was the first one.

Would the galvanized coating have made much of a difference? I know the health risk so I held my breath.

 

[snowcat]

I know the health risk so I held my breath.

that can be a serious health risk

 

[brightspark]

that can be a serious health risk

especialy if your slow at welding .i brazed some screws on to some 1/8 galve fencing wire that was bad enough [GASP]

 

[Welderpaul]

Always grind the galvanised finish off before welding, taking care not to thin the metal. Galv fumes are horrible.
It also means that by the time the arc has burnt through the galv coating, its also had time to burnt through the sheet.

 

[Wozzaaah]

I see! So it's actually THREE runs to make one joint!

I know you get more than your fair share of flak on here but I genuinely do admire your tenacity, most people would have thrown the towel in long ago.

 

[GeorgeB]

I see! So it's actually THREE runs to make one joint!
I know you get more than your fair share of flak on here but I genuinely do admire your tenacity, most people would have thrown the towel in long ago.

But three runs is only one more than used for text book MIG welding, isn't it !!

1st run - tacks
2nd run - main seam weld - that's what I hoped for
3rd run - a second seam

That's also no different to what a pro might do with root, cap, etc.
Or someone with a MIG who decides to 'go over it again' like I did.

I agree most people give up on arc welding too soon, because they throw in the towel too early. It's really not that difficult. i.e. to get a strong joint without blowing holes. Would MIG be that strong? As for cosmetic appearance, that may come if I persevere and practice a bit more. For many joints, I regard appearance as less important than strength.

 

[Wozzaaah]

In theory yes, but it's still far too time-consuming and costly for thin stuff, double run = double the amount of filler deposited. There's also the added time and cost of grinding the great globs of weld off afterwards.
'Going over it again' is pretty pointless, it often adds no strength to the weld as the only material you're penetrating is the weld bead, not the parent metal.
The only purpose it has is to make it look more presentable.
Regarding pros doing root/fill/cap etc., that's completely different and has nothing at all to do with what we're discussing here.
It's not that people give up on arc welding, it's just that most realise that it's just not an ideal method for material that is just too thin to achieve acceptable results.

 

[GeorgeB]

'Going over it again' is pretty pointless, it often adds no strength to the weld as the only material you're penetrating is the weld bead, not the parent metal. The only purpose it has is to make it look more presentable.

In my case - this test piece - I don't see it as pointless at all! It wasn't done for strength or appearance but was my first ever - amateur - attempt to try and arrive at a joint which might be waterproof when I weld a similar joint on a tank which I'm making to hold oil. Perhaps I'll try a butt joint instead. I thought a lap joint would be easier. I'm sure this is nothing to do with the metal being too thin. The inadequate first bead was due to my inconsistent rate of movement across the peaks and troughs of my tack welds. I need to go back to the drawing board. This is fully achievable - arc welding a lap joint on 1mm steel sheet - I just need to get neater tacks, which should lead to a neater final bead.

I'll agree on one thing - arc weld beads can look fine as you go, but then gaps appear as you remove the slag afterwards. If using a gas mig, I guess the weld bead you see is the weld bead you get, which would certainly be easier to monitor, as long as the gas doesn't get blown away, and you have resources to purchase and store a large gas cylinder.

 

[oilcooled :)]

my sister would put down a better looking bead than tat george thats not a weld, thats messing at its best

 

[knoba]

George... I would have thought, you would have had better results, by setting up your joints differently...

In the diagram below, the first joint is a butt, by placing a thin "filler strip" over the (ungapped) joint, it will provide some much needed additional filler material, & a better heat sink. The strip will need to be clamped & lightly tacked along its length & a "whip-back" technique could be helpful to reduce the heat input. Penetration would be achievable through both 1mm sections of parent & filler materials.

Another option (last outside corner joint) is to extend "filler lands", from each joint face, to add the extra filler metal. A "lead-in plate" would also ease the "cold-rod" transition.



Which begs me to ask the question: Given the rule of "diminishing returns", how do you expect to learn, & improve, with your choice of set-up?