I have no experience in welding other than a 20 minute tutorial by a now ex-in-law who's a boilermaker. The 'ex' means he is not available to answer questions any more. A couple of years ago, when Masters was still around, I picked up a Stick Welder on special. Cigweld WeldSkill Turbo 140. It has been sitting in an unopened box since. Now finally a project has come up that might make use of it:I want to build a rack to sit on top of my 7x4 trailer. That rack will hold a roof-top tent and an awning plus I want to keep the option open to transport a kayak or similar as well. That rack will replace the cage that the trailer came with. I have identified the strongest parts of the trailer that are best suited to take the load - basically the same spots that the cage was connected to, and lower down, the main frame of the trailer. Before I start buying materials, I wonder if someone here with welding experience can answer a few questions. The parts of the rack that will be subject to the most lateral stress will be the horizontal supports that hold the roof top tent. About 60kg for the tent when towing, 200kg+ when stationary and tent is in use. Those supports need to go across the whole trailer width. Looking at options I can get sufficient load rating with a very comfortable margin from either square 40x40x2 tubes, rectangular 50x20x2 tubes or 40x40x3 open equal angles.The open angles have the highest strength, lowest weight, lowest price and, being 3mm thick, should be easier to weld for a beginner with less risk of creating holes. Question 1) other than aesthetics, is there any reason that I might have missed that makes tubes preferable over angles or should I just go with the angles seeing all the advantages just listed?The vertical parts of the rack will face much lower lateral forces, I would be happy to use smaller material. I.e. if I go with open section: 30x30x3mm open equal angles. The main advantage I see from that: weight reduction. The trailer is unbreaked and will be towed by a smallish 4WD. I would like to keep total loaded weight to below 450kg. Question 2) any reason not to mix different sizes in a project like this? Question 3) I will probably have a choice of plain or galvanised steel, my preference (less need for protective painting) would be galvanised. I have become aware of the toxic fumes that welding galvanised steel produces. I would weld outside wearing a respirator. Any other downside to using galvanised other than slightly higher cost?Question 4) since I am a beginner in welding, how can I test the strength of my welds? Or should I, just to be on the safe side, add nuts & bolts as extra protection in case a weld fails?I might ask more questions later, but I want to make sure I take into account the answers I get to these ones here.


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