Doing a welding course - notes as I go

[Ed Poore]

Control?

[FridgeFreezer]

21 minutes ago, Badger110 said:

Is there a benefit to using Tig on steel over Mig? 

Honestly most of the time, no. MIG is the pump-action 12-bore poop pistol for steel work unless you're doing something fancy.

TIG takes 2-4x as long, but you can (in theory) get neater welds, with better heat control and a posh finish - the real benefit of TIG is you can go from steel to ali to stainless to dissimilar just by changing filler rods & settings. With MIG you've got to change wire reels, maybe liners, maybe gas, maybe use a spool gun...

TIG is quite "clean" and quiet but the test pieces that were a ~7 second MIG run are more like a ~20 second TIG run even for the tutor, and you've got to be a lot more controlled about it.

You can't get under a car with a TIG torch and filler rod and wave it in vaguely the right direction of a patch and pull the trigger. With MIG you can point the gun upside-down sideways into a nook you can't even see, pull the trigger and get a weld into an awkward corner of chassis. With TIG you'd have to hang the car from the ceiling and come in on a wire like Tom Cruise in Mission Impossible before even thinking about getting a tack weld on

[lo-fi]

Lol. Yep. I always look at it this way: if you can't do the job on a bench with 1000 lumen lighting, classical music playing, phone off, and after a yoga session, you probably can't TIG it. Justin on TFS does roll cages in situ, but he's a 10,000 hours of practice kinda pro. MIG is going to be king for a hobbyist for years to come yet. 

What amperage were you running on those tig pieces? Looks like you might have wanted a bit more juice and been able to move a bit faster? 

[FridgeFreezer]

1 hour ago, lo-fi said:

What amperage were you running on those tig pieces? Looks like you might have wanted a bit more juice and been able to move a bit faster? 

The amps were ~55 to ~70 can't remember exactly what, I think it was ~55 to ~64 for the lap joints and ~60-70 for the tee pieces.

The super skinny filler wire didn't help, it takes so long to feed in an inch of it just to get a little blob compared to the thick stuff that just takes a small dab.

[Ed Poore]

I found if I was using a lot of filler wire it was sometimes easier to lay one down along the path of the bead and then if you feel ambitious you can feed in a second one by hand...

[landroversforever]

59 minutes ago, Ed Poore said:

I found if I was using a lot of filler wire it was sometimes easier to lay one down along the path of the bead and then if you feel ambitious you can feed in a second one by hand...

One reason not to do that, it means you can’t see you’re melting the complete root of the weld. 
If you’ve only got thinner than ideal filler rod, you can double them up pretty easily. 

[discomikey]

On 3/15/2020 at 11:28 PM, Badger110 said:

Is there a benefit to using Tig on steel over Mig?  

 

There definitely is. There are also a few downsides so you couldn't blanket state that one process is better than the other. 

Let me dig through my photo album to see if I can find some good examples of when each was better

[discomikey]

Here is a bracket which demonstrates the use of both processes. 

I designed this to incorporate "thickener" plates in the areas local to the bolt. 

I opted to use TIG for the thickener plates for 2 reasons:

1. due to the proximity to the edge of the main plate. Much better edge heat control means I didn't overheat the steel.

2. Because it's prettier and prettier means the racecar is faster

The downside as mentioned above is it would have taken me half as long to physically weld, and the prep would have been much quicker if I had chosen MIG. 

The rest of the assembly was MIG welded in position on the vehicle. Time and access were a big factor here. 

Cleaning the steel before welding is still important for MIG though. 

[Badger110]

Do you weld for a living?  Stunning work

There is a markable difference in the Tig and Mig welds.  

The Tig is defineatly making the racecar go faster

[FridgeFreezer]

 

The Tig is definitely making the racecar go faster

On the flipside, TIG can make the race car take so long to build that it never gets to the start line. Ask me how I know that

[Cynic-al]

On 3/17/2020 at 9:48 PM, FridgeFreezer said:

On the flipside, TIG can make the race car take so long to build that it never gets to the start line. Ask me how I know that

That's every project I start!

Interesting to see your using 1mm rods, I assume also a 1mm tungsten? I have been using 2.4 so maybe I need to go thinner... 

[lo-fi]

1 hour ago, Cynic-al said:

That's every project I start!

Interesting to see your using 1mm rods, I assume also a 1mm tungsten? I have been using 2.4 so maybe I need to go thinner... 

Don't waste your time. Been there, done that. Bought the 2.4 and never looked back. You need to be doing some very fine stuff and have considerable skill to make tiny tig rods work. I'll try and find the TFS video where he explains. 

[FridgeFreezer]

1 hour ago, Cynic-al said:

Interesting to see your using 1mm rods, I assume also a 1mm tungsten? I have been using 2.4 so maybe I need to go thinner... 

Nope, the 1mm rods are just what the college had - TBH I get the impression that they struggle with the financial department to order appropriate consumables in a timely manner, I guess like any institution with an accounting department! Chances are someone looked at welding rods and decided the 1mm ones were better value because you get so many more of them in a pack

I've found 2.4mm rods are waaay easer as they're easer to grip for feeding but also you only need to feed a little dab each time not 20mm of it!

The tungstens in the rig I'm using are 3.2mm, others are 2.4, not sure how much effect it has really for the average user - my home rig is on 2.4mm.

I honestly don't think it's worth getting hung up on details like that for learning though - I dare say you could achieve similar results with a 1.6mm, 2.4mm or 3.2mm tungsten and with 1mm or 3mm rods, just like you can MIG the same joint with 0.6mm wire or 1.2mm wire absolutely fine, you just adjust your feeds & speeds a bit to compensate.

There's no "golden" combination of bits & settings that leads to amazing and perfect welding, it's a big grey area where a big range of stuff is absolutely fine and it's just down to you & your hands/eyes/ears to hook it up.

For 99% of stuff the most common consumables will be cheapest and therefore likely the best option, very few of us here will ever do anything that requires anything more special.

[Cynic-al]

I was trying to weld some 1mm and kept blowing holes. Was going to try to put a big lump of steel behind it but then thought if it blows through then I've just welded it to the big lump of steel!

Think I just need to put the time into practising. 

[landroversforever]

2 minutes ago, Cynic-al said:

I was trying to weld some 1mm and kept blowing holes. Was going to try to put a big lump of steel behind it but then thought if it blows through then I've just welded it to the big lump of steel!

Think I just need to put the time into practising. 

With TIG? It takes practise and you’ll blow more holes to start with, but whack the power up and go in quickly. To put less heat in with TIG you need to go hotter and quicker. 

[Cynic-al]

Yeah I think your right I'm too slow. I can do it on a flat surface but I'm trying to put two pieces together at 90 degrees then weld on the outside of the joint. On the plus I did spend a lot of time practising filling holes. 

[Ed Poore]

5 minutes ago, landroversforever said:

To put less heat in with TIG you need to go hotter and quicker. 

Or get a fancy TIG with pulse 

[FridgeFreezer]

49 minutes ago, Cynic-al said:

I was trying to weld some 1mm and kept blowing holes. Was going to try to put a big lump of steel behind it but then thought if it blows through then I've just welded it to the big lump of steel!

On the course they have a load of big chunks of ali + steel kicking around, if you're doing steel you can work on a lump of ali, if you're doing ali you can work on a lump of steel - brass or copper also work for both, natch. Big lumps are also very handy for weighing stuff down, propping bits up, and general work holding.

1mm is very thin, most of the bits we've done have been 1.5mm at least, it's far easier for learning on if it doesn't melt away.

[discomikey]

10 hours ago, Cynic-al said:

That's every project I start!

Interesting to see your using 1mm rods, I assume also a 1mm tungsten? I have been using 2.4 so maybe I need to go thinner... 

2.4 tungsten should be absolutely fine

 How are you sharpening it? That's the biggest thing. 

 

For a 1mm outside corner joint you don't need much power at all. Probably somewhere in the region of 20-30a? (I use a footpedal so couldn't give an exact figure)

As FF says, there is no golden rule. My travel speed and torch height will be different to yours and amps will need to be different to compensate. 

On an outside corner joint fit up is 200%key. You shouldn't need a filler rod at all in that situation (1mm steel). If you do you don't want to be adding much filler at all. Just zip along the joint. Pulse is preferable but without also works. You just need to use less Amps without pulse than with

[FridgeFreezer]

Well it looks like last night will have been the final night although the tutor did say he'd try and get us back if possible.

Given the situation he basically threw it open and said "practice what you want to practice", chopped up a load more test pieces and roamed around helping people with whatever they needed.

H spent the evening a little frustrated at getting the coordination right for TIG but I think she made progress, the overly heavy torches and thin filler definitely make it less easy than it could be.

I started with a "little job" to do...

Tutor had copied a TIG torch stand design off t'internet, got the BTEC engineering stoodents to cut the shapes out and he threw this one at me to tack to the bench hopefully it's not too ugly.

As this was going to be the last chance, I asked for a crack at aluminium and was granted a pile of test pieces and rods   plus a quick demo;

The three welds together are same settings but different frequencies - short one is 100Hz, next is 150Hz, the fat one is 50Hz. It's a small difference on a fairly big torch like this (3.2mm tungsten) but you can see it.

So, my attempt...

In some ways the ali was easier - certainly a nice fat filler rod was easier to handle, and you can see the shiny molten pool easy enough - but heat is a major issue! When you start off it takes a fair bit to get heat into it (tacking is tricky) but once you're half way across it's running away from you and splurging out - and if you run a 2nd bead straight after it's suddenly VERY different and you gotta move FAST!

Let's try a T fillet...

I think not enough amps but it went surprisingly well - I'l take it!

Let's throw a few more out...

I mean, they're all stuck together - cleanliness definitely makes a BIG difference, the pieces were plastic-protected one side and scabby the other, and once the scabby oxide layer forms it's like the skin on a rice pudding, you're melting what's underneath and just making a mess!

3 in a row showing how the result changes as the plate heats up - same settings each time!

 

This one the plate went like soggy tissue paper after the 2nd bead, possibly because it was hanging over the end of the large ali block;

Oxidised like hell too, I guess from heat + air

 

Running more beads on a previous piece which had a bit more heat capaccity due to being several bits joined together:

You can see I got 3 very similar results in a row with that - ali is VERY sensitive to heat build-up then!

The scummy side of the metal;

Welded OK all things considered but definitely not "how it's done".

This might be one of my better ones of the evening:

 

And this one, knocked out as closing time approached, is definitely the nicest I've done:

Shame it's just a straight bead on a flat bit of ali

[lo-fi]

For what it's worth, it's a hell of a lot easier with a pedal. You can taper down the amps as you get into the run and the part is heat soaking. Some nice beads, though! 

[Cynic-al]

12 hours ago, discomikey said:

2.4 tungsten should be absolutely fine

 How are you sharpening it? That's the biggest thing. 

I shaped it to a point, usually I dull the end but with that I kept it sharp as I thought it might concentrate the weld a bit. I was at 50 amps but with a foot pedal so less than 50 amps depending on how I was trying to stop it blowing whilst still welding. The joint wasn't perfect, there was a gap to fill as it was something I had folded so the radius of bend left a gap, maybe that and my speed were the problem. I think the other problem I had was it was a box so I couldn't rest my hand on the bench like I could with a flat piece. I had it resting on the end of a brick and was a bit wobbly. The welder does have pulse but I will have to read into it to use it. I will have another go!

I don't think you can complain at that welding FF, I would be happy with that. In the real DIY world you can just let the job cool between welds. 

 

 

Edited March 20, 2020 by Cynic-al

[FridgeFreezer]

Maybe this would help?

 

[landroversforever]

54 minutes ago, Cynic-al said:

I shaped it to a point, usually I dull the end but with that I kept it sharp as I thought it might concentrate the weld a bit. I was at 50 amps but with a foot pedal so less than 50 amps depending on how I was trying to stop it blowing whilst still welding. The joint wasn't perfect, there was a gap to fill as it was something I had folded so the radius of bend left a gap, maybe that and my speed were the problem. I think the other problem I had was it was a box so I couldn't rest my hand on the bench like I could with a flat piece. I had it resting on the end of a brick and was a bit wobbly. The welder does have pulse but I will have to read into it to use it. I will have another go!

I don't think you can complain at that welding FF, I would be happy with that. In the real DIY world you can just let the job cool between welds. 

For the grinding, what orientation are you grinding? The marks need to go along tungsten.

For the resting, a flexi torch really really helps, but if you haven't got that, and even with one, I often stick a g-clamp or similar on the workpiece just as a hand rest. Sometimes when you're in the groove and the height is right I can do it without but 8/10 I stick something on there as a rest.

[landroversforever]

11 hours ago, FridgeFreezer said:

H spent the evening a little frustrated at getting the coordination right for TIG but I think she made progress, the overly heavy torches and thin filler definitely make it less easy than it could be.

Just looked back through to the pictures... how is she holding the torch? I can post a picture later if its of any help, but I generally hold the torch with my thumb and middle finger, that then leaves the index finger for the button. It also makes a huge difference if you have the torch lead wrapped round your arm as it stops the tendency to lean the torch backwards.