Thread: Thinking about TIG - is it the wrong hammer for the job?

I'm fairly new to TIG, but I have found welding Duragal to be a bit of a pain to weld with TIG (compared to black steel). This is mainly due to contamination/mess from the galvanising.

As much as I love the TIG process, I tend to shy away from welding Duragal with TIG unless the job was particularly fiddly and difficult to do with stick ... and then I would spend a lot of time removing the gal to minimise any issues.

The reason I bought a MIG was because I was doing lots of galvanised (dura/supa gal) stuff. On the face of it, TIG is not a great process to use with galvanised material generally. However it can work well - it just takes more prep, but you can get an excellent result.

With TIG you obviously have to grind (flapdisk) off all the gal on the outside of the joint (I usually ensure at least 1cm from the edge). The issue is that the any zinc on the inside of the RHS that you can't grind will also start to find its way into the weld (and onto your electrode) if you get full penetration of the joint. If you have really good fit up and don't penetrate excessively (as in no actual keyholing), then you can avoid nearly if not all of the zinc issues.

You could also cheat a little by running a quick low amp tig bead around the joint to effectively seal the zinc inside, then a high amp cover pass. Once again, good fit up will limit issues of suck back of zinc contaminated material into your weld area.

Apart from the zinc issues, the type of joint you describe would be perfect for TIG and this process is a joy rather than a chore. TIG is usually a case of doing it once and doing it well.

Cheers

- Mick

Originally Posted by WelderMick

Apart from the zinc issues, the type of joint you describe would be perfect for TIG and this process is a joy rather than a chore. TIG is usually a case of doing it once and doing it well.

I agree - despite my current issues, I love using my TIG, especially on thin stuff. I'd use it more if the gas was free.

Michael

Originally Posted by Legion

I seem to do an awful lot of welding with Duragal (not coated on the inside) and Supagal (coated inside and out). The choice boils down to what is available in a particular size. It's all been with stick up until now, but I'm thinking I might like to give TIG a go.

My suggestion starts with an "M" and ends with "IG". Provided you're not too hung up on bead profile, which can be improved with technique, CO2 gas is cheap and works very well with gal and also blasts through rusted and painted material. Welding 1.6mm Duragal is a doddle, and even narrow corners are entirely doable as the increased stick-out of the wire seems to be compensated by the crowding of the shielding gas.

With my UniMIG combo unit, I can be running gas MIG while also having the stick lead on hand (wired up as DCEP) and with a flick of a switch, can change to stick without having to touch the ground lead.

Originally Posted by RustyArc

My suggestion starts with an "M" and ends with "IG". Provided you're not too hung up on bead profile ...

Yeah, I keep hearing that. Thing is, not only do I like making things difficult for myself, but I am kind of hung up on bead profile. Up until now, everything I've done has been outside garden stuff but I've got some inside projects and if I could make the welds a feature (wishful thinking, I'm sure) that would be awesome. I quite like great tig welds.

But mig makes sense, that's for sure. I've got access to a couple of machines but only used it a few times.

Some of the machines I'm looking at (higher end reputable brands), DC only due to $, some of them have pulse controls. While this seems like a cool idea, does anyone actually use pulsed DC TIG and how useful is it? I.e. some models have a pulsed and non-pulsed variant with a few hundred $ separating them.

Originally Posted by Legion

Some of the machines I'm looking at (higher end reputable brands), DC only due to $, some of them have pulse controls. While this seems like a cool idea, does anyone actually use pulsed DC TIG and how useful is it? I.e. some models have a pulsed and non-pulsed variant with a few hundred $ separating them.

Yep, primarily when welding thin stainless but sometimes when welding thin MS.

I don't have pulse on mine, so maybe I don't know what I'm missing, but I've managed to quite easily butt weld 0.9mm MS sheet without using any filler.

Having said that, it is obviously a usable and useful feature, although not essential, so it really comes down to whether you are prepared to pay for it. As a hobbyist I tend to forgo time saving and ease of use features in favour of a lower purchase price. In a production setting I would have a different mindset.

Originally Posted by Vernonv

As a hobbyist I tend to forgo time saving and ease of use features in favour of a lower purchase price. In a production setting I would have a different mindset.

Yes... same here.

On the other hand as a sole operator/hobbist it is nice to know you can do anything and not be limited (so having extra features is actually good and I'm willing to sacrifice convenience to have those extra features). As an example, I'm happy to have my TIG machine double as my Stick machine - and put up with swapping leads around. If I was in production, I would have 2 separate machines.

Regarding pulse. I do have pulse features on my TIG and very rarely use them and I know plenty of people who are the same. Personally I reckon a few hundred extra dollars wouldn't be worth it for the general hobbist. I'd put the extra $$ towards a good auto helmet or ensuring you had HF start on your TIG. Having a good quality/clean/clear helmet really does pay benefits with TIG welding. I have a separate helmet for stick welding and it gets treated pretty roughly, has splatter marks, etc. etc.

As I and others have said previously - MIG is really the go to process for what you describe - it depends on what other capability you want.

Cheers

- Mick

You can always use muriatic acid (30% hydrochloric acid) from a pool shop to strip the zinc off the ends of your tube. Just put an inch in a container and balance the tubes so the ends are in the acid. It will bubble, so make it a deep container. Use a lid to keep old stuff. You can use it again until it doesn't bubble anymore. Do it outside though and don't breath any fumes.
It only takes a few minutes and then you put the tube ends into sodium bicarbonate solution to neutralise the acid. You get that at the pool shop too. Makes the steel like new, but with no galv.
Its a bit messy but you get great results. I use the old stuff to kill weeds, but then, I hate gardening and don't care if nothing grows there again. it always does anyway.
It's a relatively safe acid because it hurts immediately if you get it on you, and washes off easy. Old clothes and glasses might be a good idea.