More arc welding questions

[drum]

I've switched form using a mig to an arc welder and have a few 'issues'!

I can get good welds under the following circumstances - welding on the flat using 3.2 rods and 130 amps. Most other situations are causing me problems. I'm welding 3mm mild steel mostly but some 2mm too.

When using smaller rods I struggle with the rod sticking to the work piece.

For vertical and overhead welds I can only make headway by stitching first then filling the gaps. Any attempts at continuous welding in the vertical or overhead positions ends up with the weld pool falling. If I try moving faster I get no penetration.


What's the secret/technique? Is it the rods? What rod size and settings do you use for vertical or overhead? I use 6013 esab. I know lots of practice is required but I want to practice in the correct way and with the correct set up. Any advice greatly received.

 

[penfold]

Smaller rods are bendy which makes life hard when you're learning, although the sticking may be crappy or badly stored rods or too low amps.

 

[ChrisJohnsSculpture]

With vertical and overhead welding part of the knack is to move the rod in a pattern which compensates for the tendency of the weld pool to drop. One technique for vertical welding is to set up the work with a small gap (less than the thickness of the rod) or vee groove and concentrate the heat on either side of the groove/gap quickly flicking across the joint and pausing on alternate sides, as the pool slumps a bit it will tend to be drawn towards the middle of the weld. Another way to think about it is that you're building up a series of ledges as you go which freeze and give something for the next ledge to sit on like a staircase.

There are quite a few different variations according to personal preference and the exact conditions but it basically comes down to understanding, visualising and controlling the weld pool which no amount of explanation can really get across adequately.

I would suggest that the best approach is to practice on horizontal welds until you can produce consistently good welds without thinking about it then move onto sloped, then vertical then overhead welds.

Also check out the tutorials on here and around the web in general which will show you a variety of approaches in more detail. Videos are often useful. Don't assume the the first one you see is right for you but play around with a few and see what works.

It's perfectly normal to find positional welds more tricky than horizontal ones.

 

[chunkolini]

Good advice fro Chrisjohns.
Get a good feel for it right way up than change your parameters.
Suddenly it clicks.
I dont do any Arc welding but I can remember vertical Mig welding being hard and upside down bloody impossible. Now I can do both quite happily even left handed when needed.

 

[drum]

Thanks guys, Chrisjohns I'll give that a go. The stitching method I'm using is working but involves stopping and starting and doesn't look very good.

My welding on the flat is ok provided I spend long enough on the preparation side of things.

One other question - sometimes my welds have all the colours of the rainbow. Well, at least red, gold and blue. What is the significance of these colours?

Thanks again.

 

[ChrisJohnsSculpture]

Good advice fro Chrisjohns.
Get a good feel for it right way up than change your parameters.
Suddenly it clicks.
I dont do any Arc welding but I can remember vertical Mig welding being hard and upside down bloody impossible. Now I can do both quite happily even left handed when needed.

Absolutely,it's one of those things which seems impossible difficult at first and then suddenly becomes obvious and then second nature.

Be prepared to fiddle with settings, with stick you only have current to worry about so it's not to troublesome. It's a much more valuable skill to be able to adjust settings in response to what you are actually seeing than to remember any amount of amperage table.

I suspect there are a lot of welders who would struggle to remember what current you need for what rod on what thickness of metal but could set it up right on a welder in minutes without even thinking about numbers.

The colours are just various different flavours of oxides formed on the surface of the metal, they have some significance in some hot metal processes but aren't something you need to worry about for stick welding. In short they give an indication of how hot the metal was when it was exposed to air.

Ultimately welding is about producing a strong weld so its good to develop the habit of experimentation and self assessment rather than relying too much on prescribed settings and formulae. While it's not always true that a nice looking weld is good, a nasty looking weld is almost always bad

 

[rich r]

I tried several techniques for vertical welds, and the one that works for me is to have a narrow gap (about half the rod width) between the metal to be joined. Then start at the bottom, with the rod pointing up at about 45 degrees (ie pushing the weld up rather than pulling it) on one side of the gap. Hold for a second then whip across to a point just slightly higher on the other side of the gap. Hold for a second then whip back to the first side - just above the weld there (so it melts part of the slag that's just started cooling), then continue back and forth. Don't pause too long or it'll drip, and don't stop in the middle or it'll blow through. It's all about how long you hold on each side, which varies depending on the metal being welded - I guess you've got to get a balance between being slow enough to melt the base metal and allow the other side to cool enough to support the weld when you come back, but not so slow that you get things too hot and melt the weld you laid down before leading to it running. You may find a different angle works better - as again you've go to find a compromise between melting and depositing metal above the existing weld without getting too much heat, but not generating spatter and getting poor penetration.

As said above - do a search for 'vertical up' and you'll find several similar methods to try. See what works for you. I find it easiest with 2.5mm rods, but that's more than likely my inexperience.

 

[drum]

Thanks again for the advice, that gives me something to work on. I guess my question about rods etc was whether or not there were any dos or don'ts regarding rod and amps. Eg use thicker/thinner rod than normal for a given steel thickness or similarly, same rod less power and so on.

I'm getting better with practice and I'll keep experimenting with the techniques mentioned.

Cheers all.

 

[rich r]

Pick whatever current the rod manufacturer says for that type of rod. Or in the absence of that information, roughly 80A for 2.5, 110A for 3.2 and 150A for 4mm.

Go 10 or so lower if you want to slow the process (eg for vertical), at the risk of sticking. Go 10A or so higher to speed up the process (eg more penetration) at the risk of burning through.

The thickness of the metal you're welding is of less importance than in mig, as you just cut a V and build up multiple passes of weld.

 

[drum]

Ok thanks Rich.

 

[Jeepster]

Smaller rods are bendy which makes life hard when you're learning, although the sticking may be crappy or badly stored rods or too low amps.

This is correct, the flux coatings on arc welding rods absorb moisture from the air after which they no longer work properly and can prevent the arc from starting, causing sticking. They should always be kept as dry as possible...If you suspect them to be a bit damp you can simply dry them out in a normal household oven.

 

[Jeepster]

Absolutely,it's one of those things which seems impossible difficult at first and then suddenly becomes obvious and then second nature.

Be prepared to fiddle with settings, with stick you only have current to worry about so it's not to troublesome.

...And voltage. For thin materials you increase the voltage which decreases the amps...My oil cooled Oxford Arc welder has two voltage settings, 40V and 80V...The 80V setting reduces the amps by a factor of two making it more suitable for welding thin plate and the 40V setting is for welding thick plate. Cheaper Arc welders typically only have one output voltage, usually around 40-50V, making them less suitable for welding thin plate.