How to arc weld a fillet joint

Here are the steps for how to arc weld a horizontal fillet joint.

A horizontal fillet joint is when you have one piece of steel laying flat on the table and the other piece of steel sits on it's edge on top of the first piece of steel.

Here are the steps for how to arc weld a horizontal fillet joint. A horizontal fillet joint is when you have one piece of steel laying flat on the table and the other piece of steel sits on it's edge on top of the first piece of steel.

The angle is at 90 degress or right angles to each other.

For this I used two pieces of flat steel that were:

The welding electrodes that I use/used are:

• KOBE RB-26, which are E6013 General Purpose (GP) rods
• Rod diameter 2.6mm (3/32")
• All position rod = up, down, left, right, over your head, under your feet!
• Good for all general welding, fabrication and sheetmetal work. Easy to learn and use.
• Home handyman, DIY, hobby welders.

The welding range for these Kobe electrodes are 45-95 amps.

Can be used with an AC welder, and can be used with DC welder either electrode negative or electrode positive.

I used these rods with the electrode positive (+).

DC arc welders are all shipped as DC electrode negative (DCEN).

To change to DC electrode positive, simply swap the earth lead and electrode holder lead around.

Using DC electrode + will give a little bit more penetration.

Welding rod angles for a horizontal fillet weld

To weld this type of fillet joint you will need to get the weld into the corner of the joint. So you will need to hold the electrode at the half way point from both pieces of steel. This is shown in the photo below.

Note: For larger horizontal fillet welds you will have to hold the electrode angle a bit lower and closer to the bottom piece of steel.

This is because the molten filler metal will slide down the side of the vertical piece of steel under its own weight because of gravity.

The angle that you need to hold the electrode in the direction of travel, is from about 45-70degrees. This is shown in the photo below.

If this angle is too small, as in the rod is to the left more, the molten flux will pile up and flow ahead of where you are welding. And you can get slag inclusions and voids in the finished weld.

Think of arc welding a fillet joint as if you were using a caulking gun and squeezing out some sillastic.

If the caulking gun is held at right angles to the job there would be even amounts of sillastic coming out left and right of the nozzle.

Meaning that if you are moving the caulking gun to the right at keeping it at 90 degrees, you would be going over the excess silicon that was coming out of the right side of the nozzle.

Now imagine adjusting that angle to between 45-70 degrees to the right. Now when you squeeze out the silicon it would not really pile up out to the right of the nozzle. Most of it would go into the corner of the joint and away to the left of the nozzle. Can you visualize that?

Now imagine the same thing with the welding electrode.
Arc welding tip:Some welding electrodes will have more slag when you are welding compared to others. This means that you will have extra "silicon" coming out of the "caulking gun". This is where you will have to adjust your angles so that you can use the force of the welding arc to blow the molten slag away to the left of the weld, and not allow it to go infront of where you are welding.

This can also be simulated if you imagine using a caulking gun again, this time squeezing it softly and then again squeezing it hard.

Imagine when you squeeze it softly that this simulates a welding electrode that generates minimal slag, therefore it is easier to see what you are doing and you could run a slightly higher angle with the rod. This higher angle will force the welding arc into the corner of the horizontal fillet joint more, giving you more penetration.

If on the other hand you squeezed that handle on the caulking gun really hard, you would have silicone everywhere. And you would need to angle the nozzle of the caulking gun flatter to the metal so that you can keep the silicon from flowing infront of your travel path. This example would simulate a welding electrode that generates more slag build up, requiring a slightly lower angle.

Always move the welding electrode away from the puddle

You should always move the welding electrode onto new metal. Move the rod the way that it is leaning.

Fillet weld showing slag coverage

This is the finished weld, and the photo shows what the slag looks like after the weld.

Showing how thick the welding slag is

You can see here that I have knocked off half of the slag on the weld bead. The weld underneath looks pretty good so far.

Also you can see a piece of slag that has fallen off the weld. It is see in these pictures at the bottom left corner of the metal.

Photo showing finished horizontal fillet weld joint: end view

This is photo of the fillet weld end on. You can see how the weld is like a triangle shape joining the upright and flat pieces of steel together. The weld surface looks even and smooth.

The finished weld below seen at another angle.

The welding power was set in the higer upper range as reccomended by Kobe. My little stick welding machine does not show how many amps you weld at, but rather has just a rod sizing scale. As in, wind the knob this way for a 2.6mm rod or wind it the other way for a 3.2mm rod.

My estimated power output is 90-95 amps.

• Keep the electrode tip close to the corner, about 2-3mm away.
• I did not weave or whip the electrode, just simply kept it at a constant angle.
• The less shaky your hands and arm are the smoother the finished weld.