Tried welding some fillets today

Nothing wrong with those welds that practice won't cure. 145 amps on

The standard practice block is nothing more than a 6mm thick chunk of strap about 50mm x 100mm (or whatever is handy) Run a clean bead down one edge, chip the slag, inspect, run a second bead next to the first, chip, inspect, repeat until the whole surface is covered. Do a second, third, forth, etc layer. When you are done, use a per hacksaw to cut it across the beads, should have NO slag inclusions. You will not do well on the first one, it gets better with practice.

When you get that figured out, set the block on it's side, lay beads horizontally on the vertical surface, etc etc.

Full length welds like you did will warp BADLY. Only cure is to weld short sections on opposite sides (top/bottom, left/right). You can keep it from getting as bad by just doing skip welds eg 1" (25mm) welds every

Christ> Hi all,

(snip)

Distortion: tack in several places, then stitch together with alternating short beads.

General: minor imperfections noted, but your welds look entirely servicable to me. I'd say start building stuff you want to build. A little slag inclusion here and there is not gonna make a rack fall apart.

From a person 100% ignorant about welding, I must say that your welds look extremely nice. I would try cutting your piece with a chop saw to analyze penetration of the weld. Picture

As Don said, your welds are certainly serviceable. If you are in doubt weld the angles together for a length of one inch and see how much hammering and twisting you will have to do to get complete separation. People mentioned about tacking your assembly first before welding and avoiding long continuous welds. I suggest that you also avoid over welding. In many cases you do not need to weld everything up with continuous seams. A one or two inch weld on such thin material will take a considerable of load, Randy

I tried out some of your recommendations today and welded a couple of fillets. I took two pieces of 50 mm x 50 mm x 3 mm mild steel angle and clamped them back to back with about a 25 mm overlap, so that I could weld a fillet down each side. I know the steel looks rather rusty in the pictures but I cleaned off as much as I could using a wire cup brush. The rust really is very superficial.

snip

My technique looks much improved. I think I was using the wrong angles and not watching the arc closely enough. Now I reckon I just need to practice a bit to get rid of those little slag inclusions at the start of a weld, neaten up my restarts and banish the small patches of undercut and spatter. Any suggestions?

Thanks very much for the help!

Chris

I think that depth of penetration is far less important than it is often made out to be. What is important is fused area.

If you welded the end of a rod to a block of steel, would you feel that the fused region should go halfway down the length of the rod to be sound? (Of course you wouldn't!)

Width of well-fused area does have some correlation with penetration with single-pass welds, because puddles are not flat.

However, strength does depend on where metal is located relative to load moments. Penetration could be important in a filet weld if welded only on one side, to resist bending moment and avoid stress concentration. You do want weld metal in regions where the cross-section will be in tension under load, however it gets placed there. The simple guidline is therefore that significant penetration is necessary to have a strong weld. But it depends on the joint design and how the joint will be loaded.

The biggest single mistake the beginning welder (and I Strongly include myself in that catagory) are what are known as Gorilla Welds.

I can now look back at my early work and cringe in noting that Ive used what looks like a half box of rod to put something together that needed a couple 1" welds.

Ive taken to actually looking at how our everyday world is welded together, exposed joints, pipe fittings etc etc to see how the pros acomplished things. Fascinating to see exactly how few weldments are used in building big Stuff

Gunner

I learnt not to weld every possible seam a few years back when I was building an enclosure to house the control system for my power hacksaw. I tried welding a seam on the inside of the box and ended up with bad distortion. I probably do still have a tendency towards "gorilla welds", though, but I have a couple of objections to intermittent welds.

First is that I've noticed they tend to harbour corrosion. You weld everything together before you paint your project, then the paint seals the unwelded sections of the seams. But it doesn't take much flexing or weathering to open up a gap which moisture can enter. Of course the joint is unpainted inside and it rusts. You paint over it again and - damn - the rust shows through again. I hate that!

Second is that I don't like the appearance of intermittent welds if they're in a very noticeable place. I prefer the appearance of a continuous, neat bead. When I build an enclosure for my phase convertor I think I will weld continuous seams, partly to thoroughly seal the electrical enclosure, and partly to look neat.

Point taken, though: you can overdo it!

Chris

I think the penetration is better than it looks in that end-on photo because I stopped welding just before I reached the end of the seam (in the past I've managed to blow ugly holes in the metal at the end of a seam).

Out of curiousity, which of my fillets do people think would be stronger? Here are the pictures again:

Chris

I believe your second weld will be not only stronger, but substantially so.

I can't believe you're going to fabricate an enclosure box for a phase converter. I think the last one I used I paid like $18 for. Of course, I'm getting ready to make a welding rod oven, and lacking sheet metal skills entirely, I'll probably weld it up, sigh. You won't see me using 100% welds, though. I'll skip weld it together, then fill the cracks with Bondo, sand, prime, and paint. Then insulate and line. I seriously doubt it'll rust.

GWE

Is that because the heat affected zone around it is much smaller?

There are two reasons for fabricating the enclosure. First, I have no sheet metal working equipment. Second, it needs to support a 240 V ->

Best wishes,

Chris

Transformer hanging off the side ? That has to be some strong side.

I'd think about mounting the box on the transformer! Actually, I'd mount the transformer on the wall - up somewhere and run wires.

The local Home Depot has a great power panel - about the size of my living room in length and deeper than normal boxes. Massive pipes run up and down the wall - so as I was scanning the cat-5 internet link and where the server was :-) I also spotted their transformers about 2/3 up the high wall. I suppose they didn't want trucks to steer around them or have low rent people on forklifts to fork them.

The transformer might hum if locked to metal.

Don't know your shop or the actual situation. Think on this one first. You might have another way.

Martin

Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

Christ>

I want to build the phase convertor on a trolley, so I'd rather not mount the transformer on the wall. It is, however, built for wall mounting so the brackets are on the back. The neatest way to mount the transformer would be to bolt it to the control box, and if I'm going to fabricate the box it shouldn't be hard to make it strong enough. Nevertheless, I plan on wiring the phase convertor up before I build a trolley, so that I can test its performance. At this stage I can see how much the transformer vibrates.

Chris

I think the drag rod weld is a better weld for a couple of reasons: Less weld (and less heat) and more uniform. The uniformity comes from not having to maninuplate the rod. The smaller weld comes from being forced to run donw the weld line much faster. Your first weld would look the same if you had the practice and dexterity to get a clean weld. As it is, you are spending a lot of weld puddle time pasting weld all over the place.

Drag rod technique is OK to get the idea but it does not work with all rod types. Try to learn to manipulate the rod to do the same th> D>

To manipulate the rod and get a bead as tight and small as that sounds like a tough challenge. I'll have a go, though...

Don't the very sharp corners in the drag rod weld weaken it at all?

Chris

No, it's because of the evenness and correctness of the second bead. The first bead, being thicker then thinner then thicker then thinner, is much weaker where it's thinner. The second bead wastes no metal and I believe is simply more efficient at distributing forces, and thus stronger.

Why not make a simple frame from a discarded (free) bed frame, and bolt a purchased enclosure *and* your transformer to it?

GWE

I've hung a lot of transformers on boxes for the same reason (powering carts on wheels), but the approach I've used is to design a or buy a standard box (14 ga. I think), and weld a 1/2" thick plate drilled and tapped to the transformer mounting pattern on either the rear or side of the box.

By the way, I always add a structure ground to my rigs. Since they are mostly 480 V. 3 ph., I usually use green jacketed 2/0 welding cable, lugged and bolted on the frame and an appropriate building ground. Where I run a lot of carts I either bolt to wiring duct where it's rated for the fault currents, or a separate copper bus. The welding cable is more flexible than normal cable.

Pete Keillor

I think the first weld is the stronger. The answer may depend on which way the forces are. Since at least two people think the second weld is stronger, I would suggest you try to break the welds and let us know who is right.

I do think that the second weld would be more than adequate especially since you intend to do a cantinuous weld.

Dan

Christ>