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  Saturday, 12 February 2022
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Hi Aussie CycleKarts folks. So I'm working on building a cyclekart. I'll need a welder. Although I already have a tiny $100 Bunnings arc welder and can botch two bits of steel together, I'm fairly sure that won't do for my project. What sort of TIG MIG welder do I need to buy? I really have no idea where to start.

Thanks for any suggestions

Simon
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2 years ago
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#20948
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If you already have an arc welder you can just buy a TIG torch for it and use it for TIG welding. From memory a cheap torch setup is about $100 + Gas + Gas regulator. Just like stick welding you need to scratch the TIG electrode on the job to start the arc. I'm not sure how the gas feed works, I think they have a manual valve on them whereas a proper TIG has arc start and gas control from the torch trigger.

For welding steel most folk generally use a MIG welder as they are usually easier to source and for the most part easier to use. I personally use a TIG as I find it gives me a lot more control but it does take a little more practice to use. There are pros and cons to both.

in a basic sense you can think of a TIG as a MIG welder where you have to feed the wire by hand. It's this two handed operation that makes TIG tricky for some people. MIG on the other hand automatically feeds the wire at a pre-set speed, which is easier to a degree as it only takes one hand to use it, but does mean that you need to weld at a set speed as you cannot change the wire feed speed on the fly. This can get tricky when you get to corners or tricky weld orientations. This is where I personally prefer the TIG as it allows you to slow down the weld when you get to tricky parts or when you need to reorient the torch.

The type of welder also makes a big difference. Nowadays most welders are inverter based, whereas a few years ago they were all transformer based. Transformer based welders are heavy and generally only have a few different power settings - essentially one power setting per transformer tap and switches to select the power. Whereas the newer inverter style units have electronic control, and a dial to adjust the power very accurately. This is the same for both MIG and TIG (and ARC welders)

Being able to dial the power in accurately means that you can fine tune it for the thickness of material you have. With transformer based MIG welders you have to choose the next highest setting and then wind up the wire speed to match. I find that you then end up having to weld a lot faster than you would with an inverter based set especially on car body thickness panels, which when starting out can be a bit of a challenge.

Some newer MIG welders even have a digital menu that allows you to set the machine settings based on the material you are welding which takes the guesswork out of things but this kind of hokus-pokus comes with a large price tag.

If you are looking to weld aluminium it is a different ball game as you will need an AC/DC TIG set. (MIG / TIGs are generally just DC) so this might be a determining factor.

AC/DC TIG sets are a magnitude higher in price than regular DC units. AC welding is also a magnitude more difficult too

In all cases I would recommend avoiding a gasless setup. These use fluxed wire or rods to shield the weld pool. They are very difficult to get good results on and in my opinion are really best avoided by a beginner.

Bunnings offer welding gas bottle rental. You 'buy' the bottle for a fee ($250 IIRC) and then you pay for each refill ($90) Then when you are finished with it you can return the bottle to get your $250 back. This is what I do. I used to rent my bottles from BOC but the quarterly rental charge is pretty high and it soon adds up. If you do a LOT of welding BOC might be more cost effective as their refills are a lot cheaper.

Welding wire / welding rod thickness is another big consideration. This is governed by the thickness of the material you are welding. If you are welding typical car body thickness you should be running something like a 0.6-0.9mm filler wire / rod. Running a thicker rod takes more heat to melt and you can easily end up burning the job away just trying to melt the filler into the weld pool. This is especially true with car body metalwork which is usually only 0.9mm

Shielding gas type is determined by the metal that you are welding. For steel and steel alloys you generally use the MIG gas (you can use this with a TIG too) but for aluminium you need to use Argon. You can also weld steel with argon but the arc burns a lot cooler so you use more gas and it is slower going.

Another consideration... From a car body / metal-shaping perspective MIG welding creates a harder weld and a more brittle heat affected zone (HAZ). TIG weld HAZ is not as hard as MIG and can be planished, which is needed for metal finishing and very important if you plan on metal shaping. Gas welding creates a fully malleable weld and is usually the preferable way to weld car metalwork. A properly executed gas weld is also indistinguishable from the parent metal as the HAZ metallurgy is not changed as it is using MIG / TIG. This is why you will never see a professional metal-shaping shop use a MIG on a skin panel.

This is a very simplified overview, there's lots more to welding and setting the job up but it might give you some food for thought.

The TIG torch on your existing Arc welder might be a good cheap option but you might have a bit of practice to do before you get good results. Check out Youtube for TIG filler rod feeding exercises. You can get some practice in before pulling the trigger.

MIGs are great when they are set up properly as they are kind of set and forget but a bad MIG setup can frustrate the most patient of people. If you get a good inverter MIG set then it will be a good all round machine and handy to have

A dedicated TIG set is generally a step above the kind of MIG welders you would find in Bunnings but are a lot more flexible when it comes to weld control.

Moving up to an AC/DC TIG opens up the possibility of welding non ferrous metals too but this kind of machine is starting to get expensive.

That's my 02c FWIW
2 years ago
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#20949
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Great write up, Mick. :) Much more than I was expecting as a response. It's given me some great guidance - thank you for taking the time.
Simon
2 years ago
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#20950
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No dramas at all. You are most welcome.

I really struggled with MIG welding for a long time and think that most of this was the welder I had - a transformer style MIG - basically the same one you could buy from Bunnings or many of the tools shops. Power setting #1 was not high enough and Power setting #2 was far too high. I was using too large a diameter wire for the job (because that's what it came with) and was also trying to use gassless wire too because I was too cheap to rent a gas bottle, which really did not help. I still have this setup and can now get okay results from it (I use it outside where the wind usually makes using shielding gas difficult and only on thicker gauge steel) Moving to an inverter TIG set was a night and day difference due to the extra fine control that it gave.

One other thing that I will mention, if you have ever soldered or brazed with a gas torch TIG is almost exactly the same as far as torch and filler wire control is concerned except without the flux.
2 years ago
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#20971
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For anyone that's interested I have a bit of an update to this thread. I decided to invest in a small portable inverter TIG welder as my big unit is simply too large to drag around.

My main prerequisites were lightweight and cheap. Also as I only wanted to weld steel, it only needed to be a DC set.

Looking around (on ebay) I saw that there were many cheap inverter DC welders that could be used as a TIG set. Most were not dedicated TIG welders, but stick style welders that could be used with a TIG torch. This kind of setup is what's known as a scratch start set. which means that to initiate the arc, you need to touch the electrode to the work piece. This is fine and not really an issue, but for a few dollars more you can get a HT start. This style of welder initiates the arc using a High Tension spark which is initiated when you press the button on the torch / pedal which is what I'm used to with my other unit.

Looking for HT start welders puts you into the dedicated TIG welder territory, which also means you can get units with adjustable pre and post flow. What this does is start / stop the gas flow before and after the arc. This means that gas is applied before the arc is struck and also supplied for a time after the arc is extinguished which ensures that the arc is always shielded and helps minimise inclusion (weld contamination). Often with scratch start sets there is no gas control at all and the gas has to be controlled manually. Which means opening a valve before you weld and then remembering to shut it off afterwards as well.

The good thing about a dedicated TIG set is that they usually integrate the gas control and also include the TIG torch.

The unit I decided on was a Giantz 220amp unit which was just shy of $200 delivered. This particular unit had a 60% duty cycle at 180amps which is enough to weld 6mm. The until will also weld up to 220amps but at that kind of power the duty cycle drops to 40%. It will happily weld thinner materials all day long which makes it perfect for things like 1mm body panels. It also included gas post flow control. The pre-flow is however unfortunately pre-set but no real biggie.

https://www.ebay.com.au/itm/284723697842

s-l16003.jpeg

The unit arrived pretty quickly and I set it up for a quick test. The results were pretty good. the arc is nice and stable and it has plenty of power. The unit itself is very lightweight, in fact ironically the gun cable is heavier than the actual welder.

A quick bead on some 1mm. Not the best weld in the world but okay for out of the box

IMG_20220411_162351.jpeg

Same again but on 5mm

IMG_20220411_162403.jpeg

I haven't done a long term test on this but from what I have seen so far the results are good. The unit is light weight, The torch head is not great but replacement heads are really cheap. I ordered a more modern style with integrated trigger switch but have not fitted that yet. It also does not come with a gas regulator so factor one of those in with your purchase along with some hose. These are the items I bought for mine

https://www.ebay.com.au/itm/403564491002

s-l1600.jpeg

The torch upgrade is of course a personal preference. there's nothing wrong with the one supplied with the welder, they work fine, but for an extra $26 you can get a really nice ergonomic setup that's a lot more comfortable to use

https://www.ebay.com.au/itm/194753004780

s-l16002.jpeg

The regular is necessary. I prefer the flow style regulators which incorporate the flow gauge as you get a good visual indication of the flow. Needle style gauges are great but I personally find that it's much easier to read the floating ball. This particular one is offensively cheap which I can only put down to being produced in surplus for covid (as oxygen regulators). They fit the standard argon / MIG gas bottles which is the main thing.

A quick note on welding gasses...

You do not need to use argon for steel, you can happily use MIG gas for TIG welding. It is generally the metal that you are welding the dictates the gas type and NOT the welding process as most people assume. MIG GAs / Argo shield will work fine for TIG welding steel.

In summary I'm pretty happy with the welder, the tests that I carried out were good, the welder behaved as good as my big Miller AC/DC unit. Weld power control is good with 1mm being pretty easy to handle. I did not try it on thinner material but I suspect that it work work well. There is unfortunately no foot control but for a portable unit that should not be a deal breaker.
2 years ago
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#20972
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Brilliant and informative further discussion, Mick. Thank you!
Simon
2 years ago
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#20974
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Votes
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For anyone that's interested I have a bit of an update to this thread. I decided to invest in a small portable inverter TIG welder as my big unit is simply too large to drag around.

My main prerequisites were lightweight and cheap. Also as I only wanted to weld steel, it only needed to be a DC set.

Looking around (on ebay) I saw that there were many cheap inverter DC welders that could be used as a TIG set. Most were not dedicated TIG welders, but stick style welders that could be used with a TIG torch. This kind of setup is what's known as a scratch start set. which means that to initiate the arc, you need to touch the electrode to the work piece. This is fine and not really an issue, but for a few dollars more you can get a HT start. This style of welder initiates the arc using a High Tension spark which is initiated when you press the button on the torch / pedal which is what I'm used to with my other unit.

Looking for HT start welders puts you into the dedicated TIG welder territory, which also means you can get units with adjustable pre and post flow. What this does is start / stop the gas flow before and after the arc. This means that gas is applied before the arc is struck and also supplied for a time after the arc is extinguished which ensures that the arc is always shielded and helps minimise inclusion (weld contamination). Often with scratch start sets there is no gas control at all and the gas has to be controlled manually. Which means opening a valve before you weld and then remembering to shut it off afterwards as well.

The good thing about a dedicated TIG set is that they usually integrate the gas control and also include the TIG torch.

The unit I decided on was a Giantz 220amp unit which was just shy of $200 delivered. This particular unit had a 60% duty cycle at 180amps which is enough to weld 6mm. The until will also weld up to 220amps but at that kind of power the duty cycle drops to 40%. It will happily weld thinner materials all day long which makes it perfect for things like 1mm body panels. It also included gas post flow control. The pre-flow is however unfortunately pre-set but no real biggie.

https://www.ebay.com.au/itm/284723697842

[attachment]s-l16003.jpeg[/attachment]

The unit arrived pretty quickly and I set it up for a quick test. The results were pretty good. the arc is nice and stable and it has plenty of power. The unit itself is very lightweight, in fact ironically the gun cable is heavier than the actual welder.

A quick bead on some 1mm. Not the best weld in the world but okay for out of the box

[attachment]IMG_20220411_162351.jpeg[/attachment]

Same again but on 5mm

[attachment]IMG_20220411_162403.jpeg[/attachment]

I haven't done a long term test on this but from what I have seen so far the results are good. The unit is light weight, The torch head is not great but replacement heads are really cheap. I ordered a more modern style with integrated trigger switch but have not fitted that yet. It also does not come with a gas regulator so factor one of those in with your purchase along with some hose. These are the items I bought for mine

https://www.ebay.com.au/itm/403564491002

[attachment]s-l1600.jpeg[/attachment]

The torch upgrade is of course a personal preference. there's nothing wrong with the one supplied with the welder, they work fine, but for an extra $26 you can get a really nice ergonomic setup that's a lot more comfortable to use

https://www.ebay.com.au/itm/194753004780

[attachment]s-l16002.jpeg[/attachment]

The regular is necessary. I prefer the flow style regulators which incorporate the flow gauge as you get a good visual indication of the flow. Needle style gauges are great but I personally find that it's much easier to read the floating ball. This particular one is offensively cheap which I can only put down to being produced in surplus for covid (as oxygen regulators). They fit the standard argon / MIG gas bottles which is the main thing.

A quick note on welding gasses...

You do not need to use argon for steel, you can happily use MIG welders(like this) for TIG welding. It is generally the metal that you are welding the dictates the gas type and NOT the welding process as most people assume. MIG GAs / Argo shield will work fine for TIG welding steel.

In summary I'm pretty happy with the welder, the tests that I carried out were good, the welder behaved as good as my big Miller AC/DC unit. Weld power control is good with 1mm being pretty easy to handle. I did not try it on thinner material but I suspect that it work work well. There is unfortunately no foot control but for a portable unit that should not be a deal breaker.

Hi and thank you for sharing! Looks very decent. Wish you all the best. Welding isn't an easy job
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