advice on whether I am expecting too much

[MoreWellie]

I have been (slowly) teaching myself to weld using a 151TE and have got to the stage where I am rebuilding a battery box and have let a number of sections in but I am not confident that the welds are as good as they could be

I am putting in new sections of 2mm and in some places welding overlaps and in some places butt welding

The two pictures show a corner that has had a section roughly 25mm wide let in and it butts up to a new end panel on one side and the old metal on the other

I am using the welder on max 2 (5 out of 6) for power and using 0.8mm wire and 5 on the speed control for new to new and 4 on the speed for old to new (because I started blowing holes in the old stuff) I was expecting to see the weld through to the other side and I do (just) on the new to new joint but don't on the old to new. I didn't have a gap or a V because I thought at 2mm I shouldn't need it

What does the panel think?

Mike

 

[rikrobson]

It Looks like its not penetrating enough. Also the old material still looks a bit resty. This should be clean metal. If the inner is edge is overlapped that would explain. the corner that has penetrated is butt, the welder is not penetrating two layers.

 

[MoreWellie]

I only cleaned around 3mm of the edge as I was butt welding to the old stuff. I was cleaning with a grinding disk and it tended to make to make it thin quickly so I just did what I thought was sufficient, how much would an experienced person clean for a butt weld?

How do I increase the penetration, 2mm should be well within the capability of the machine so I presume it is my fault.

The power is already up at 5 out of 6 and any faster wire speed I got blew a hole. I am still using disposable bottles and with the valve screwed fully open I only get around 3L/min (using weldequip nozzle flow tester) but as it doesn't seem to spatter I thought that was ok

Should I leave a gap?

With only 2mm thick presumably it is not necessary to make a V

 

[rikrobson]

I'd cut back to good solid metal. you are just asking for trouble if you leave it a bit rusty as it will come back.

I'd try with some test pieces. My Little BOC130 will quite happily blow though thin metal on the lower settings if i put too much heat in one place.
I would have thought that a 151 on high settings would penetrate 2mm, but if you are lapping 2mm with 2mm, that's 4mm and if you are not holding them clamped tight they are not going to touch everywhere, which will give an air gap and therefore not penetrate.

I'm no expert and usually fiddle around with the settings to get it right as sometimes the least intuitive settings work better, Don't forget its not just about settings on the machine, but also the technique used also. So less power but a slower stitch weld may solve the problem.
Less power to stop blow through. slower movement to let the heat penetrate and a stitch to not put to much volume of heat in any one spot.

 

[MoreWellie]

just to make this clear the weld in discussion is a butt weld not an overlap

The sawn edge was bright metal and I cleaned about 3mm on the side of the edge as I am going to wire brush the whole thing after the repairs

I have some more to do tonight so I will try less power and even slower although I was moving relatively slowly, maybe 5mm per second but that is a guesswork figure

thank you for your suggestions

 

[Cris B]

I think Rik's saying that the metal that you haven't cut out and have welded onto still looks quite pitted and therefore was rusty previously, notably in the first photo. Without seeing a wide angle photo it would be difficult to know the extend of that rust on the panel, but you might have been better chopping a bigger section and adding in a larger repair patch.

If it's 2mm thick then you're at a very close point to where I was when doing the chassis rail repair on my project. It's thick metal. It has some surface pitting. Do I leave it and treat it with rust specific paints or chop it out for piece of mind, but create more work for myself...

Impressed with your welds in any case. Shame about the penetration as noted, maybe going a little slower would give it more time to penetrate?

 

[rikrobson]

Yup, I'd be inclined to cut further in passed the reddy area. perpendicular and just past the 3 rusty spots. The yellow will be sulphuous from the battery acid, so i'd also think about cleaning that up a bit before painting.
The other option is to run a bead along the non penetrated edge. with the bead on the other side it shouldn't blow through.

 

[MoreWellie]

Thanks for the pointers, I will run a bead over the inside and see how that takes. I have already spent ages rebuilding this battery box and my son wants it to get on with his rebuild

I am starting to get a feel for the settings and how to produce good looking welds, but am not good enough to get them looking good all the time and I have a tendency to wander off line and produce test welds on solid metal :-))

it was primarily the lack of apparent pentration that was concerning me now and I was hoping that someone would say change this setting and the world will be sunshine and light. At least I now know to spend more time on preparation and weld more slowly

Thanks again
Mike