welding steel base or just getting aluminium extrusion

[Boyan Silyavski]

I welded it on the floor, using the larger beams themselves for base. Basically the correct way will be to spot weld the outside frame. Then make sure all is straight and knock here and there with the big mallet. Then weld. Then insert inside beams, use scrap or washers to adjust to a tight fit so after welding it does not contract.

Do not worry, first frame ever i welded with stick welder and was welding for first time.


The main thing to understand when welding is very simple but crucial: "You are making a molten pool and moving it around" . All else serves for that to happen, that means you must think only about that, not thinking angles of electrode, this and that. See that pool, maintain it and move it around or up and down. That's it. I believe many welders do think of other stuff than the pool when welding. I am talking about DIY welders like us.

[reefy86]

thanks boyan, about the frame do you think i am on the right track with the frame design? i just want to get the design nailed so i can crack on with pricing and getting required tools ect.

[m_c]

Weld it on as flat a surface as you can.

If I was going to do something like that, I'd be buying a big spirit level to ensure the main frame was set as level as possible to welding, and a big set square for ease of checking things are square during initial setup (I'd also be measuring corner to corner to check squareness after the initial tacks are in place).

If you order metal pre-cut, you may still have to grind it to length, as cut tolerances can be quite big (typically -0mm to + several mm).

As for welder, I'd go for something in the 150-200A range. You won't need that much capacity, but at that rating you shouldn't need to worry about duty cycle. Ideally gas MIG is better, but the cost of gas can mount up if you're using disposable bottles, and the rent on full size bottles is quite costly. There are suppliers where you can buy bottles, but you really need to find one locally, and check to see how much the gas works out to per litre (some of the schemes where you buy bottles don't fill bottles to that high a pressure, so you don't actually get much value for money).
Other option is gasless MIG using flux cored wire, but then you have to deal with flux/slag cleanup afterwards (best way to describe is, is it's pretty much ARC welding, but with a roll of wire instead of rods).