Welding Tips and Tricks

Newbie question
it's easy enough to fuse 1/8" plate but if you're looking for full strength weld what is the proper joint prep and technique?

when I tig welded two 1/8" plates together and turn the sample over, am I supposed to see a bead on the back?
that would require way more heat then I'm using right now.

can you just weld both sides?

or should you always bevel the joint and tack with a gap?

thanks in advance

Are the 2 plates being welded flat? I'd suggest a 30 degree bevel on the plates and a small gap then use the appropriate filler and put a nice bead down.

When plates are butted you may not get all the way through to the backside with out using too much heat.

Depends on application, material, use, etc...

Thanks for the input.
The plate will form a gusset for a motorcycle frame, mild steel. I beveled the edge but left a little land. I'll see if i get adequate penetration.




Interesting on fillet welds, you don't get complete penetration and a good fillet weld is measured by the throat size as long as the root is well incorporated.

A lot more to welding than just melting metal.

Found this
http://mewelding.com/welding-butt-joint/
which has a nice chart that looks like from some textbook.
bad on them for not referencing it.

but it gives different joint preparations for different thickness metal.

looks like on 1/8 you could weld both sides.

1/8" plate I wouldn't bother with edge prep and I wouldn't care if there was no gap. If I had the choice I'd put a 1/16" or 1/32" gap, just because I find it easier to see the progression of keyholing. But if I fit up the parts and they came up flush I also wouldn't hesitate to weld it up. That's not thick and if you give it enough heat it should penetrate just fine. The only reason I'd weld both sides is for appearance but that doesn't seem to be an issue in this case. Plus, if you weld the pieces before they're in place you have to deal with warping and once they are in place it's going to be very difficult to weld the back side.

From the looks of it the right two tacks had more than enough heat. The left one can be ground down a bit and then you're good to go. You've got a nice little gap too. Disclaimer - amateur hobby welder, experts might disagree.

How much heat are you using that it concerned you in the first post? Looks like you must have some scrap from this project so you can experiment a bit on it. I'd be starting with the recommended 125A and if that's not enough, bump it up 5A then another 5A at a time and see what happens. Got a pedal? If so you could try starting at 140A or so and riding the pedal. That's going to be more than enough based on my (weak) experience.

I ended welding both sides and ground the underside flat as I'm going to fillet weld a length to it to create sort of an I beam to support that middle section of the frame.

I was welding at 110amp with the foot pedal. Any hotter and the bead has that dull grey overheated look. Maybe from not big enough gas coverage?

I don't know. I tend to tig weld pretty fast and never wait to see the keyholing. Whenever I slow down, the weld bead turns grey and ugly. Maybe I'm doing something wrong.

That chart really helped give me an idea of what is considered thin medium and thick steel plate. I would feel comfortable welding 1/16" (16g?) on one side in one pass. But it's nice to see that 1/8" can be welded on both sides or gap it.

For the distortion, I clamped the piece after tacking on a block of aluminum to help back it and keep it flat while cooling.