AC TIG pad.

[Richiew]

I saw an interesting old video from welding tricks and tips about doing a pad for alloy TIG.

I found that doing a pad for stick welding was very helpful to me so I thought I'd have a go.


The 1050 plate is 6mm thick roughly 150mm by 200m. It's a cheap and efficient way to get a lot of beads down. I still have the other side to weld too and there's another half to go as well. £7.76 bought me a 300mm by 200mm sheet on ebay which I cut in half.

I started at about 150amps at the edges and then increased the power to about 165amps. 2.4mm blue tungsten and 2.4mm wire, 180hz. Managed to touch down about 8 tungstens, usually at the ends of the weld run when my right arm was running out of easy travel. Welder is a AC/DC Stealth. My craters are getting a little better with a 1.5 second downslope plus a backstep and late fill but I am wondering if the thick material is helping and masking problems. On 3mm coupons the crater sometimes went nearly all the way through but the ones made here are well above the parent material. It has helped me get a bit more familiar through watching the weld and understanding how it behaves. The ac buzz gave me a stinking headache by the end of it. It was a good test for the welder and torch.

Still can't feed the wire even if my life depended on it.

 

[tom2207]

You couldnt tie shoe laces when you wore slip ons either .. today you dont even think about tying a a bow , its second nature , all it takes is time and practice , looks like your off to a great start , so its just practice ,, maybe a freq change if its giving you a headache , and / or hearing protection . Remember too that your concentrating really hard too that does not help ,, take a break and relax , the thing most folk forget to mention when learning to weld ,,, cups of tea and digestives ,, almost as important as your mask .... well ok , not quite but a break now and then helps the eyes arms and neck too.

 

[AndersK]

Once it's 30 mm thick you'll feed rod in your sleep

That drill is the best practice one can get.

 

[Barking Mat]

That looks well good.

 

[Richiew]

Cheers, it's a bit Curate's egg, good in parts. Middle of the weld is hunky dory. Start can be a bit interesting as the tungstens were sharpened to a point for steel so as they rounded off the arc length increased which had to be compensated for. I sharpen a whole box at an end of a session and just swap them out as needed in the next sesh. At the end of today I just got rid of the contamination and put a very blunt end on them. Should make my starts a bit easier tomorrow.

Ends are still a bit of an issue but I think it's more cosmetic than structural, at least on this thickness. I think I will try a 2 sec down slope and see how that goes. I had tried a few lap welds prior to this on 3mm plate but heat management was the major issue for me. Welding and dabbing is so much faster compared to mild steel. I find the thicker plate help though as on 3mm the material gets heat soaked very quickly and the welds drop through the floor. The thicker stuff gives a more regular response.

 

[Richiew]

Well tonight I welded the reverse side. It was very scratched and mucky so I gave it the stainless brush treatment but it was never going to be as clean as the plastic covered side. I amended a few settings. Set the downslope to 2 seconds and the end current eventually reduced to 25amps in order to control the crater stops, they were getting better by the end. I found welding towards myself at roughly 15 degrees helped ( A bit like the angle in the picture). It gave me the best view of the torch and arc length. I was getting more comfortable and I only scored two touchdowns. The outside welds were a bit of a mess, I think due to muck and heat control. I was really comfortable by the time I got towards the centre. I think I want some better gloves so I can feel and grip the rod better and maybe get round to feeding it some time.

 

[tom2207]

wow ,, the results are way nicer , and in a relatively short time , well done . Light gloves are important , and actually not that dear .

 

[Richiew]

I think it it just getting used to the machine. DC starts so much nicer than AC. Getting familiar with how it goes is half the battle. On another thread Munkul said "Don't start low, Aluminium doesn't like it." I know exactly what he means.

I finished a City and Guilds in DC tig over a year ago but I'm out of practice since. I managed to pass the course the lazy way doing some laywire and walking the cup for a fair bit of it so I never developed much technique.

 

[Munkul]

Looks really good! Especially considering that you say you can't feed rod!

Proper TIG gloves are essential IMO, especially starting out. To be fair, I've seen folk wearing all sorts, but personally I prefer a dedicated set or two.
I like Ultima Deerskins, they work well for me, others prefer Ultima Gold because they're a little harder wearing, but not quite as supple.

Then practice feeding rod. Sit in the house and do it in front of the telly, was the advice given on here when I was learning...

What balance setting are you using? It looks like your etched zone is huge. Three things that affect etched zone are balance, arc length/stickout, and cup size. Not a problem per se, just an observation, especially at this stage it doesn't matter.

6mm plate will forgive more amps and absorb more heat etc, if you try some 3mm plate next, you will be around 90 amps or thereabouts, less on the edges.

 

[Richiew]

Cheers Munkul,

I have ordered a set of gloves with a grabby thumb area to see if they help. Up to now I have just used the standard grey tig gloves that seem to be everywhere.

The cleaning action / AC balance on the Stealth goes from +3 to -3. I had it on -1. I will lower it to zero which is where it should really be anyway. I'm using a number five cup and the fact that I only touched down twice might suggest the arc length was a bit long. I am using a sensible stick-out, about 5mm. Torch is showing in the first photo.

I know the thick plate is flattering my welding a bit but it is good to be able to watch and react to the puddle. I can tell when it's starting to get too hot and increase my travel speed and feed more rod. It's teaching me to learn to manage the puddle rather than just blindly weld and end up with a sunken mess. I'll continue a bit longer with the other half of the 6mm plate and then get back to 3mm stuff to see if I have improved at all.

 

[Richiew]

I had go with the other half of the plate. I had a bit trouble at first. It was cold today and a had a thick sweater on under the overalls. There was a lot of tight/bunched material in the crook of my arm. Everything has got tighter during lockdown (ahem!). It all got a bit bound up as my right arm bent towards me, hence all the touch downs. I removed the sweater and things improved. I couldn't get quite as comfortable today.

I tried experimenting with the balance. It actually runs from -5 to +5 on the settings. The manual is rubbish and doesn't even explain which side is which. I ran the two extremes on a bit of scrap plate and I could see a difference but it doesn't seem to matter what I choose with this material. I had a look at some of my other practice welds on 3mm plate and I could see they were much shinier and showed less cleaning. I also noticed they were ran at a lower frequency, the welds looked hotter and gloopier for want of a better word so I thought I might have a go at 60hz to see if this helped.
This pic is at 180hz. Not too happy with it but things improved towards the end.

This two pics below are the 60hz side. 150amps. The plate was left to cool before I welded this side (Dinner). I really enjoyed doing stops and starts with this. Thick aluminium is very forgiving and easy to restart. The cleaning action gives away the restarts on the beads but otherwise they run really well. I set the downslope end current to 5amps and this has solved my crater problem. I get a small dimple at the end but nothing I couldn't polish away if I wanted to. Its not a crater anymore. 60hz is slightly easier to listen to as well. I think the cleaning isn't so pronounced. This was all welded with the balance in the middle. Still not as shiny as some other welds I've done. Material might be a consideration.

Anyway, I'm very happy how the second side went. Onto 3mm plate next. Heat management won't be half as easy.

 

[Munkul]

I've only just worked out what's going on in your picture! lol

So you aren't overlapping the welds like i thought - I wasn't looking at the pic properly.

This is your next task. You'll stack your bead onto 1/3rd of the previous bead like this

Forgive my wavy beads, this is 3mm and I was out of practice)
Pay attention to your tungsten when you change the balance - one way will ball the tungsten as the amount of AC % is going up. The other way, you should be able to grind a taper on a 2.4 tungsten and just the very end will round off.
Whatever you settle on, you want the rounded end to be smaller than the tungsten diameter. The smaller the point the better, some machines are better than others at looking after tungstens.

Tidy beads though. You'll crack it no bother.

 

[Richiew]

Cheers. I didn't want to overlap them at first as I wanted to something pretty to review. It would make efficient use of the material to bunch them all up. I'll find the side I like least and weld over the top of it using the overlap.

Impressive on the right hand edge there Munkul. That's a lot of fast dabbing/travel to keep the heat in check.

 

[AndersK]

Don't worry about pretty too soon, but they do look good .
Just keep filling and filling. When a full layer is done rotate 90° and keep going . You'll be amazed how little amps you need when it's 20 mm thick and once heat saturated.
Wire brush every now and then when needed. If you get it too hot to deal with just dunk it in water.
This is not proper way but for a practise piece it just gives you more seat time.

 

[Richiew]

Cheers Anders, I will give the cold water a try. I don't want to cook my new gloves when they arrive. The ally and the steel plate get very hot during a session.

 

[Richiew]

Had a go on 3mm today. Wasn't brave enough to start right on the outside edge and I still managed to become a cropper at 90 amps where it became all hot and out of control in the bottom left corner. I got a bit more confident towards the middle and ended up increasing the current to 95amps. I felt fairly in control once I got familiar. It felt a bit cold in a lot of places. I wonder if the 12mm steel plate was too much of a heat sink at times?

I had a go at some lap joints at around 105 to 110 amps. I think all the pad work really helped set me up for this. I do well with "Mr Miyagi" style learning. Heat control will come with practice I suppose. Generally too cold at the start and then the heat runs away at the end. Restarts don't help as the torch lingers longer. Fairly pleased with how it went. Touched down far too often today though. I might have to get the pedal out to control the heat. I don't want to start messing with pulse until I get the basics sorted.

 

[Richiew]

I've been getting used to the pedal recently. Found it really important to get comfortable and to be sat at the right height so my foot rests on the pedal without pressing it down. Here's a few pics of some butt welds and outside corners. I feel like I am improving. I had a little light bulb moment today realising I need to travel much faster to keep the heat down. I was struggling to move my arms while keeping a tight arc but I am getting better at this. I need to get feeding rod through my fingers though. The pics show welds on 2mm and 3mm flat bar. I found 2mm a bit easier after working with 3mm. I can get a puddle going and get moving quicker with the thinner stuff. I've bought a bigger lump of 6mm steel plate to work off and it manages the heat a lot better than than that small piece of plate I was using previously.

 

[tom2207]

thats all looking great , its amazing when something clicks into place ,, soon it will all be like that ,,, you can weld those plates to each other now too , and try some T joints , all sorts of shapes to play with there

 

[mtt.tr]

Very impressive. Keep it up

 

[Richiew]

Thanks for the kind comments. I took the hint and had a go at some lap joints and fillets. I stuggle a bit with fillets but lap joints aren't so bad. I think it is the vertical plate getting in the way of the torch that gets me. Anyway, I decided to try some pulse welding and a little laywire so I could concentrate on torch position and not have to worry about dabbing. I know it is a bit lazy but its quite instructive as I can watch the weld pool and focus on torch postion. I found it helped me a lot and I managed some reasonable welds. I didn't take any pictures as I was re-using the old pieces of material.


As I had made some reasonable fillet welds I thought I'd have a go at pipe to plate. I've made myself a weld postitioner, it's still a work in progress and there's a thread about it here:
https://www.mig-welding.co.uk/forum/threads/weld-positioner-lash-up.79199/

Next job is to fit a voltage display for repeatability as volts = turntable speed.


Here's my attempts. The first one went best I think.

3.2mm wall tube, 1 and 5/8" diameter.
3mm plate.

190 amps peak
90 amps base current
1 hz pulse
120hz AC frequency.
Balance, somewhere in the middle.

The pedal was used to drop the peak amps once the weld got going. I blew through on one of the pieces.

I've got another 6 feet of tube and some more plate to experiment with. The machines are doing all the work for me so I should be able to fine tune things a bit.

Bespoke inlet manifolds this time next week