Welding

[carlyai]

Just starting on the house roof rafters which consist of 100 X 50 X 2 mm metal rectangular box sections that form an A and welded at the top and to the house pillar reo. I was wondering why the welder would not continue the arc for a complete weld but kept breaking the arc after about 2 secs. The explanation was that the wiring from the PEA would catch on fire if he drew a continuous arc. Fare enough. So from the 15(45)A PEA meter he is using one phase, which is about 50m of what looks like normal PEA cable, then from a knife switch for about another 30 m of 4 mm cable to the welder. So I think I can see his problem that if he is welding 2 mm rectangular box sections together and is drawing 80A for the weld (just a guess) then by welding for 2 secs on and off he won't burn down the cable (i guess this is from his local knowledge), but the welds are something else.

I could increase the size of the cable size of the 30 m run to 10 mm but I am not sure this will help. If you have about 230 Volts and 80 Amps then you have 18KVA supply.

Can I buy a Mig of a TIG welder, or as I have a supply of around 18KVA changing welders won't solve the problem. The weld at the apex of the rafters is probably not that critical as the two rafters or the hypotenuse of the sections are pushing together so not much downward force from the tiles, and the extremities of the span (nearly 7 m) is positioned on peers with reo rod to weld to.

We won't be going to a welding shop, but is there anything I can do to get a good weld under these conditions?

[carlyai]

I have done a couple of days about 5 years ago and my other welding experience was as a first year trainee about 50 years ago, so not much would be the answer.

[arthurwait]

What do you mean his welds are something else. Can you take a picture of them ?

Edit: Good or bad ?

[carlyai]

Sorry, the welds don't look too good, as if the metals have not run together along the weld, but eventually, as he continues to weld over again, the small sections of welds each look OK. i asked him if the welder was OK and he said 'yes'. I asked him if the power was Ok and he said 'yes', that was when I found out he welds the way he does because of the incoming power cable. My thought was that I could buy him a new Mig of Tig (which I don't really know much about) if that would solve the problem and use it myself later.

[stoneyboy]

Probably not much unlike this I would imagine.

From personal visual experience here.

[carlyai]

No, no, no, much better than that. I wouldn't have let him weld if it had been like that. It's just that I would like a continuous weld if possible. My internet is sooooo slow I can't upload pics from here in Issan.

[casualbiker]

Maybe look at inverter welders

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[seedy]

Probably not much unlike this I would imagine.

From personal visual experience here.

ImageUploadedByThaivisa Connect Thailand1399282226.662211.jpg

Welds like that are called 'Bird Sh*t' where I come from

[gerry123]

where i come from its called YOU'RE FIRED

[carlyai]

Thanks for the replys, having some internet trouble and been watching rockets. Will get some pics up when i can. I was probably a bit hasty about the qulity of the welds, as the rafters have had multiple reinforcing tubing inserted and welded together, so it looks very strong. There is a 100A breaker on the phase input to the welder and it hasn't tripped and the smaller diameter wire has not started smoking so all OK.

I would probably like to re write my question, and ask what type of welder should an old bloke like me buy to do some welding (green houses etc), that I don't have to get a buffalo to push it around? Someone mentioned an 'inverter' welder, but am not sure what type or brand of welder that is.

[andrew55]

I would probably like to re write my question, and ask what type of welder should an old bloke like me buy to do some welding (green houses etc), that I don't have to get a buffalo to push it around? Someone mentioned an 'inverter' welder, but am not sure what type or brand of welder that is.

CasualBiker is on the right track when he suggests an inverter welding machine.

The TIG is a great tool for 'special' metals. MIG is great for thin section. The job on hand is 2mm and whilst MIG is probably ideal it is heavy enough stock to be quite easy with a stick welder.

The inverter welder is certainly the most versatile unit and 'old bloke' friendly. By changing the supply from from a pulsing AC to a smooth DC it becomes much easier to control the weld. Not much dearer than a heavy old AC unit. Also much smaller/lighter - you can sling it over your shoulder.

I'd also suggest an automatic welding mask. Cheap enough and will make it easier to concentrate on the weld.

One more thing. Make sure there is adequate ventilation. Especially so If that is galvanised section that you are welding. You'll end up feeling like you've had a bender on the home-made Lao Kow... If you're not experienced get someone to hang around as an observer/ assistant for safety reasons (good idea if you're welding OR drinking home-made Lao Kow).

Best of luck.

[carlyai]

Maybe this is stretching it a bit, but do you have an inverter welder name that is avaliable here in Thailand? I have used the automatic welding mask before and a great invention. I'm off to Mukdahan tomorrow If you can give me a brand name I'll have a look. Thanks.

[casualbiker]

Many brand names.. all about the same (within price band)

What shops you going to? If not a local shop then Thaiwatsuda or Global house (but not in a storm) have decent ranges.

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[casualbiker]

The boxes will say "inverter " or just ask for an "in VER TA wel DER"

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[impulse]

I bought a cheap 160A inverter welder about a year ago, and it's great for jobs around the house. Cost about 5,000 baht- but I shopped around a bit.

If you're around BKK this weekend, BITEC has a trade show going on May 15-18 where you'll have your pick of dozens of brands of inverter stick, MIG and TIG welders, along with zillions of dollars of high and low budget machinery. I was also able to find welding rod in 1.6mm, 2mm and other sizes you just can't find in normal BKK stores, along with different grades (6013, 7018, etc), and SST rod.

For me, it's one of the "don't miss it" events in BKK every year.

Easy to get to- BangNa BTS station, and it's free to attend. Bring a business card (any business card, really) to save a little time waiting in line at registration.

Your 4mm cable is right between 10AWG and 12 AWG, rated by NEC for about 20-30 amps (at your 220V, should just about be enough to weld okay since the welding voltage will be a lot lower at 80A) . I suspect the problem is the long run of cable and voltage drop- plus you didn't mention the size of the run of PEA cable- which I suspect is 2.5mm and inadequate (but not sure without more info). A proper run of cable may just sort out your problems. Problem is, with the price of copper, buying an adequate 80m run of cable will cost a lot of coin.

Also, do you say he's on a 15A breaker?

[soihok]

Single phase welding machines always seem to be under powered and results are hit and miss (my personal experience), but as 3 phase isn't widely available outside commercial and industrial estates there is only one other choice, but we are starting to talk serious money.

Diesel powered SMAW machines. Not really viable for the odd job now and again, but for jobs where no power is available they are essential.

What is possible is to get hold of a small diesel gen set 3 phase, say 10KVA and run a 3 phase inverter SMAW machine off that. Bit of a run about though.

For the odd job here and there, an inverter SMAW single phase should be fine (rods of 2.6mm diameter, 3.2 too big for 2mm thick section - normally 6013 is ok, but for the roof I would go for 7018).

Sounds like your supply cable is too small for the length it has to cover. Upping the cable size is your only option, or move the power source closer to the job (small diesel gen set - you possibly hire one).

We have some serious ESAB MIG 450A welding machines on the job here in Malaysia, welding plate up to 100mm thick (lifting eyes).

MIG requires you use gas bottles, be it CO2 or a mix of CO2 and Argon, so not really for the odd job.

[stubuzz]

Automatic welding masks are not the best. If the lense isn't fast enough to react, you will get an initial flash in your eyes.

[impulse]

MIG requires you use gas bottles, be it CO2 or a mix of CO2 and Argon, so not really for the odd job.

Flux core wire eliminates the need for gas when using a "MIG" machine, but has its disadvantages. Main one (for household jobs) is that the MIG machine is a lot more expensive than a comparable amperage SMAW (stick, or MMA) machine. Still I know a lot of guys who use flux core wire around their garage and farms back home. They were trained on MIG and it's just natural to go with what you know. And they don't have to haul around big gas bottles in the back of their pickups. Me, I use stick for the tiny amount of welding I do.

Single phase machines for 220V seem to be limited to 250 Amps, though most companies seem to hold out 200 Amps, which is probably more honest. 110V household machines like back home are even more limited and then the size of your breaker needs to be considered. Thai machines will be 220V.

I was at BITEC yesterday and they had literally dozens of brands of welders on display, in all price ranges from a $ hundred up to the CNC robotic jobs for $$$ millions. Lots of safety gear, like auto darkening helmets that are hard to find in Thailand, too.

Well worth a visit to be awed by machinery out the wazoo. The show continues from 10:00 to 19:00 today (Sunday), and I have found that some of the exhibitors would rather sell their samples than pay to haul them back home near the end...

[soihok]

Strictly speaking, why would you want to eliminate the gas when using MIG (unless you have no gas of course)?

I'm not teaching anyone to suck eggs, but Metal Inert Gas welding speaks for itself.

Flux cored wires and solid wires offer good results without the need to constantly stop and change electrodes (SMAW).

Wouldn't dream of using a MIG machine without the gas, we would just use stick (SMAW) - bear in mind we test all critical welds by ultrasonic third party tests.

[soihok]

The show sounds great by the way

[T_Dog]

Has anyone bought a Flux core wire welder here in Thailand? Wondering if there are any good models available? A friend back in the USA bought one for about 70 bucks US and is welding very thin wall tubing with it. He had no welding experience either which makes it even more impressive.

[impulse]

Strictly speaking, why would you want to eliminate the gas when using MIG (unless you have no gas of course)?

I'm not teaching anyone to suck eggs, but Metal Inert Gas welding speaks for itself.

Flux cored wires and solid wires offer good results without the need to constantly stop and change electrodes (SMAW).

Wouldn't dream of using a MIG machine without the gas, we would just use stick (SMAW) - bear in mind we test all critical welds by ultrasonic third party tests.

As you have pointed out, MIG without the G isn't MIG. But it can use the same machinery used for MIG, without needing the gas.

Guys use the gas when they're in the shop, but don't want to haul the gas out to fix that axle on the tractor out in the back 40 acres. A roll of flux core wire, and it's all good.

There's also the benefit (over stick) of not having to constantly stop to replace the stick, restart the arc and hope you haven't left a void.

SMAW also requires dry and relatively fresh rod, where flux in the center of the wire can't absorb moisture.

On the other hand, I don't know anyone that uses flux core on critical welds that need ultrasonic testing.

[stoneyboy]

Strictly speaking, why would you want to eliminate the gas when using MIG (unless you have no gas of course)?

I'm not teaching anyone to suck eggs, but Metal Inert Gas welding speaks for itself.

Flux cored wires and solid wires offer good results without the need to constantly stop and change electrodes (SMAW).

Wouldn't dream of using a MIG machine without the gas, we would just use stick (SMAW) - bear in mind we test all critical welds by ultrasonic third party tests.

As you have pointed out, MIG without the G isn't MIG. But it can use the same machinery used for MIG, without needing the gas.

Guys use the gas when they're in the shop, but don't want to haul the gas out to fix that axle on the tractor out in the back 40 acres. A roll of flux core wire, and it's all good.

There's also the benefit (over stick) of not having to constantly stop to replace the stick, restart the arc and hope you haven't left a void.

SMAW also requires dry and relatively fresh rod, where flux in the center of the wire can't absorb moisture.

On the other hand, I don't know anyone that uses flux core on critical welds that need ultrasonic testing.

Your last statement regarding Flux core is way off the mark I'm afraid,as most heavy structural full pen welding is now undertaken using Flux cored wire,quite the opposite to what you said.

[impulse]

On the other hand, I don't know anyone that uses flux core on critical welds that need ultrasonic testing.

Your last statement regarding Flux core is way off the mark I'm afraid,as most heavy structural full pen welding is now undertaken using Flux cored wire,quite the opposite to what you said.

I'm not claiming to be a definitive input for all things welding. I can only pass on my personal experiences. I don't know anyone, because everyone I know that uses flux core uses it "on the ranch and in the garage".

Thanks for setting the record straight. I'll do some Googling...

Good info.

[andrew55]

Automatic welding masks are not the best. If the lense isn't fast enough to react, you will get an initial flash in your eyes.

Are you sure this is a problem encountered? I've done a weld or two in countries with high workplace safety standards and automatic shading lenses have been the norm for a long time. I assume that means that they meet or exceed pretty stringent standards testing prior to regulatory approvals. Even the cheapies need to meet these standards. The shading kicks in at something like 1/10,000th of a second I think and my understanding was that there was no problem with that.

Correct me if I'm wrong - I've been married for a looong time so can take it.

Funny line I once heard from a taxi driver in Oz driving past a drunk wannabe passenger - he reckoned the drunk was "blinder than a welder's dog".

[andrew55]

Strictly speaking, why would you want to eliminate the gas when using MIG (unless you have no gas of course)?

I'm not teaching anyone to suck eggs, but Metal Inert Gas welding speaks for itself.

Flux cored wires and solid wires offer good results without the need to constantly stop and change electrodes (SMAW).

Wouldn't dream of using a MIG machine without the gas, we would just use stick (SMAW) - bear in mind we test all critical welds by ultrasonic third party tests.

Gasless (flux-cored) can be useful when outside as as it tends to shield better in a breeze. Makes sense.

[stubuzz]

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Automatic welding masks are not the best. If the lense isn't fast enough to react, you will get an initial flash in your eyes.

Are you sure this is a problem encountered? I've done a weld or two in countries with high workplace safety standards and automatic shading lenses have been the norm for a long time. I assume that means that they meet or exceed pretty stringent standards testing prior to regulatory approvals. Even the cheapies need to meet these standards. The shading kicks in at something like 1/10,000th of a second I think and my understanding was that there was no problem with that.

Correct me if I'm wrong - I've been married for a looong time so can take it.

Funny line I once heard from a taxi driver in Oz driving past a drunk wannabe passenger - he reckoned the drunk was "blinder than a welder's dog".

I first encountered an automatic lense about 15 years ago when one was given to us on a try and buy basis. Everybody that used it complained about the initial blinding flash.

Maybe the newer models have overcome this problem.

[impulse]

I had one that was solar panel powered, it was very good. Of course ones eye must see the flash for a split second, but I had no problems with it at all.

I don't know if I could have ever learned to weld had it not been for the automatic darkening helmets. I'm just not that good with doing multiple things at once.

Even the cheap solar powered one I have in Thailand works like a champ. I also had several in China, but kept on giving them away to the welders doing work for me. I felt bad to see people damaging their eyes doing my work- though they were not my employees.

My understanding is that they had some teething pains when the technology was new, but even the Chinese models worked fast enough, and cost me about $50. I didn't pay much more for the one I have in BKK.

Strangely, I could usually get a Chinese made helmet cheaper (on sale for $39 at Harbor Freight) in the USA than in China.

[Bcgardener]

I supply 3M auto darkening helmets to my welders and they work great. I have my doubts about the 1500 baht ones though as the 3M helmets are between 9k and 13k baht plus they have a lot of accessories like magnifying lenses that clip inside (great for the older guys whose eyes are not so good) I think you probably get what you pay for that's why I stick with the 3M ones

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[impulse]

If I were welding all day, every day, or my helmet was mission critical- I'd pay more, too. The cheap ones I buy just won't hold up. But they perform their function well as long as they stay together. (Remember, I'm welding with a 5000 baht machine, too.) And if it breaks. I can stop what I'm doing and buy 5-7 more for the same price as one of the 3M's.

I pull the kit out once a month, weld for an hour, then put it up for another month. I have lost more, given more away and left more behind when I move than I have worn out- which is none.

And after 10 years in China, I no longer subscribe to "you get what you pay for". I have spent too much time at manufacturers where they make $500 items in the morning, then use the same parts to make $100 items in the afternoon. The ONLY difference is the sticker that goes on it, and the box it goes in. A little diligence can save a lot of coin as long as I'm willing to put up with the guff from my name brand addicted friends.

I don't know anything about the 3M welding helmets, so that's a general statement, not specifically about them.