Thread: Starting and ending a weld

Originally Posted by phelum

The start is generally a bit blobby presumably because the base metal is cold.

The problem with the end is that I tend to melt too much base metal at the trailing edge.

Hi Steven,
Being blobby is not much of a problem its an easy one.
You are correct to start the electrode up on a striker plate near the weld site to overcome :

• Cold start and
• Broken and chipped electrode ends

Electrode angle for a flat butt joint is ok at say10 degrees off vertical. Consistency in maintaining the arc length will provide you with a even width and bead height .
The bead is completed by reversing without angle change say the width of your bead (back)

Consistency in maintaining an even rate of travel will sort the ripple pattern out.

To start another rod in the crater for an invisible join, strike 8 -10mm downstream and lift up that much back and settle it in to the last ripple of the last bead.The strike and resettle happens in the time space of a second.

Ideally what you are seeking is a shape like a crescent moon. Too fast is the shape of an arrowhead and too slow is almost straight across and the bead humped up.

If the base metal is excessively hot at the trailing edge your arc length is to long or your amps setting is too high.

Being blobby at the start and having a hot trailing area at the end suggests arc length may be too long. Try to fix that first.

Arc length is set at around around the core wire diameter as a rule of thumb.

If you have a digital camera a piccy is even easier to sort out.


cheers
Grahame

Originally Posted by Grahame Collins

If the base metal is excessively hot at the trailing edge your arc length is to long or your amps setting is too high.

Being blobby at the start and having a hot trailing area at the end suggests arc length may be too long. Try to fix that first.

Thanks for this Grahame; I will experiment tomorrow. To get the arc length precision needed here I am holding the stick using my spare hand (when say half or more of full length) and welding from side to side for the best view. Please tell me if you have any suggestions here. I've tried welding towards myself (to see the front of the pool) but the stick blocks my view and I can't gauge the arc length.

I will post with a picture if I'm still stumped.

Thanks,

try welding from left to right or which ever way you feel comfortable, this what you can see what is going on. Works for me. I find that the arc length should be about the same as the thickness of the electrode.

Robert

Originally Posted by Grahame Collins

If the base metal is excessively hot at the trailing edge your arc length is to long or your amps setting is too high.

Being blobby at the start and having a hot trailing area at the end suggests arc length may be too long. Try to fix that first.

Arc length is set at around around the core wire diameter as a rule of thumb.

If you have a digital camera a piccy is even easier to sort out.

I did some short test welds joining pieces of 25x3 bar using a type 13 2mm electrode. These are small welds but it accentuates the problem (blob at weld start). What I tried today was tacking the end of the join first and this helps with the problem of excess melting at the end of the weld.

I am attaching a picture of the welds here and in case it doesn't work I have posted it at http://phelum.net/temp/P1020720-320.JPG (small copy) and http://phelum.net/temp/P1020720-1280.JPG (large copy).

The first weld (top left) was 45 amps but I really couldn't get it to work at all. The other 4 on the top row were all 50 amps and they seem better but still a bit proud (as in bumpy).

On the 2nd row the first weld was at 50 amps and I was trying to keep the arc as short as I could. The last three on the 2nd row were all at 60 amps and these seem the best to me.

If I just need more practice to get a better flow then this is fine. But if it looks like I am doing something wrong then please tell me as I am probably learning a bad habit.

Thanks,

You've got the technique down pat particularly on the last 3 at 60amps, I would bump the amps up to 70 maybe even 80, when I'm using 2.5mm rods on 3mm I would normally have the amps at around 80 maybe 90amps.

Hi Steve
Most of the welds look fine. In general you could travel a fraction faster but you ripple pattern is excellent. The bulked up look comes from the slower speed.
in terms of weld quality overall of the welding, it is quite OK.

Probably the ratio of height to width is about 1 to 3.ie width 3 times wider than high.
The next trick is to slightly spread the flat bars and allow a gap,say no more than your electrode wide.
This will reduce the height of your bead.

Judging by your pics you can handle it.

Grahame

Originally Posted by Grahame Collins

Probably the ratio of height to width is about 1 to 3.ie width 3 times wider than high.
The next trick is to slightly spread the flat bars and allow a gap,say no more than your electrode wide.
This will reduce the height of your bead.

Thanks for the prompt reply. I did have a slight gap (say 1mm) between the bars but didn't get much penetration. I'll try a wider gap tomorrow and see if I can fill it.

Regards,

Originally Posted by DJ's Timber

You've got the technique down pat particularly on the last 3 at 60amps, I would bump the amps up to 70 maybe even 80, when I'm using 2.5mm rods on 3mm I would normally have the amps at around 80 maybe 90amps.

Thanks for the tip. I was being a bit delicate with this test. I'm going to try Grahame's idea of a wider gap tomorrow but I'll start at 50 amps and work up. The 2mm rods seem to overheat when over 70 - 80 amps. I will try 2.5mm rods also; it will be quick and brutal and I'll probably blow the end away.

Steve,
Tack each end first. There is no rule that says you can't dip the piece in water.

The overheating in the main is coming from the small volume of the material. It cannot disappate the enormous heat build up in that short time.

If it were a job rather than a sample,you might weld it on a copper plate which would heat sink the heat away.

DJ's right to an extent but there are other considerations.
Your welder,your power supply,your type and brand of electrode.
All those things have a bearing on what is delivered at the arc.
Just because is says 50 amps does not mean it is exactly that .Its more of a graduated guide only.

Amps are read from the arc not on the dial IE. too hot or too cold . The dial settings just help you remember where to put the setting next time

Technique comes from experience and experience comes from practice.

I would say your 90% there

Cheers
Grahame

Originally Posted by Grahame Collins

Steve,
Tack each end first. There is no rule that says you can't dip the piece in water.

Hi Grahame,

I was tacking each end but then I changed to tacking the trailing end only. The idea is to reduce the starting blob of the weld by giving it a gap to sink into.

Your idea of a wider gap is great. I set the gap to 2mm and looked at it and said "Nah, it's far too big". But it works much better than an (almost) closed joint. I also tried 2.5mm rods and 60 - 80 amps after DJ's suggestion. It is a bit too fast for me at the moment but it gave me the idea of increasing the gap to 2.5mm to see if I could get a full penetration weld. It partially worked although this was luck more than skill.

I've wondered about the accuracy of the amp scale on the welder. I am using an Abel 130 and it is the only welder I've ever used so I can't compare or relate. It seems a good old beast and grunts and groans but doesn't get warm even with long welds at 120 amps.

I'll hunt down a reasonably thick piece of copper for a backing plate. Thanks again for your tips here. I think my efforts today are better than those of 2 days ago.

Hi Steve.
I had every confidence in you.
Who says welding can't be learnt on the Internet. Don't fret too much about the numbers.

One of the nasty tricks I used to do to apprentices, was to blank out the amp numbers with tape and make them set the amps by sight and sound.

Once they they get the feel of it (Let the force guide you,young Skywalker -sort of thing)
Strike arc ,watch and listen.Its too cold ,or just right, or too hot. I could then chuck em on any welder and they could set amps without having to resort to looking on packets and checking corresponding amp settings on machines.

It sounds like you are pretty much ready to move to the next level.
A recent post on tacking up is probably worth a look.
http://www.woodworkforums.ubeaut.com...ad.php?t=67475

I remember Abel welders. Good gear! Hang on to it.
They was made in the days when manufacturers were fair dinkum about making welders and knew how to put the right gear into them.

It will undoubtedly outlast you.
All you need ever do is to keep the connections and cabling in good order.

I happy things worked out for you so well.
cheers
Grahame

Originally Posted by DJ's Timber

... , when I'm using 2.5mm rods on 3mm I would normally have the amps at around 80 maybe 90amps.

After my recent comment about having trouble with 2.5mm rods here I decided to stop being a wimp and just do it. I did about 10 welds at 80 amps which was okay. Then I tried 90 amps but this blew the end away on both attempts. 70 amps also gave me the same effect which surprised me. Finally I tried 60 amps and got the best welds so far. I start with a long arc to reduce the initial hump and then keep the arc short for the rest of the weld.

At 60 amps it is slow enough that I can see what is happening and play with the arc length to get a nice hump on the weld.

Thanks again for the tip; I'm getting there slowly.

Good to hear that you are experimenting, it's the only way that you'll learn, keep going like this and you'll be welding like a pro

DJ & Phelum,
Here is something that may be of interest to both of you.

Say that you both had the same brand and model of welder and plugged in a set your machine at the same amps indicated on your identical machines.
Its entirely possible that the amps delivered at the electrode could be vastly different. Why would this be?

Dependent on the voltage locally available at your GPO there could be big diffrence because of the grid.At Dj's house it could be possibly only 220 volts, while at Phelum's house you may have 235 volts. Its surprising what the Multi meter can tell you.

The varying input voltages determine what amperage is available at the arc irrespective that the two machine may be set at identical amperages.
And that my friends is why the pros set the machine by running a small test bead, observing and listening and react by adjusting the machine as necessary.

Just a another rush of excrement to the brain cells.

Some photos of your new and improved beads could be nice Steve.Or even before and after photos.

Cheers
Grahame