It's a pretty decent DC welder. I got it second hand. A pico 140.

Basically the main problem seems to be that an edge on 1.5mm steel melts in an instant at the same current that
will penetrate a corner.

So if you imagine making up a T with box section, you have 2 fillet joints with close fit up. This needs a higher current as the heat is being drawn away by 3 faces. If you put the T flat on the table, these are the vertical joints.

The two horizontal joints are however more interesting. I think they are called flared bevel welds. You have an edge, a corner and a gap. So you really need to focus the heat on the corner, or it does not melt, and your weld sits on top and is as strong chocolate, and you need to build up a lot of metal, which adds a lot of heat. You barely need to touch the edge or it will melt back.

I will practice a lot more.

I also read that you can lap weld thinner material more easily, so I'm considering joining the top by putting 1.5mm flats across it and lap welding them onto the box section. Less pretty, but a lot easier. (And probably stronger than a poor quality butt weld)

Quote Originally Posted by darnthedog View Post
Hey Dave
Just a question on your Arc welder- is it an A/C welder? It has been mentioned here and on some welding sites I've that DC provides better control. And there are a few plans online to convert AC welder to DC for few $ and much cheaper than a new welder. Might allow for better penetration without the burn through. Just a thought. When I was in welding class my instructor mention that 7018 rod was much easier to strike an arc. I cannot say as I never got to use it and use Gas shielded mig now. But again these are things I have picked up on and willing to share with you and the group. Good luck.