Saturday, June 8, 2013

A-welding we shall go

I spent the day today finishing off the little stand for the hot water service tank. In my usual style I did a little SketchUp drawing first so I knew what I was doing:

I then cut all my pieces out of 30x30x2 galvanised tube and got set to start welding.. until i realised that this is going on the flat roof over the pump room, which is pitched at 1.5º. As drawn, that tilts the tank over at 1.5º too.. which is not what we want!

I'd already welded up the legs by this time and after stuffing around trying to build up one side of the legs with weld to extend them (because I hate starting the generator so I can run the chop saw) I saw reason and .. started the generator.

A little cutting, welding, grinding and spraying later, and voila!

This will have a piece of checkerplate steel tack welded on top to finish it off, and evenly support the ~400kg load of the tank when full. According to my Swiss Army Phone, I've got about 1.6º pitch on the frame, which is close enough.

As an aside, I discovered that Hebel makes a fine surface on which to weld with the oxy torch. I've done some welding (well, oxy cutting actually) directly over the concrete slab and discovered that it doesn't like that very much at all, and blisters and explodes in protest. The Hebel on the other hand, just glows orange and ignores it until it stops and I accidentally touch it, when it bites hard! I can see myself making up a nice little bench using this stuff once I get to inhabit the garage.

I spent the rest of the afternoon installing the timbers for the garage door frames. I had a quote from a supplier of fire-rated steel door frames during the week, but they wanted $1,200 each (!!) for the 2700x3500 openings, so I've decided to install timber door frames using 140x35 KDHW and flash them with steel sheet just like the window frames. Much cheaper.

So with one opening fully framed and I now know my exact dimensions, I can draw up the door frames in SketchUp and get stuck into them tomorrow.


  1. Hey Simon,
    Was wondering if I could get a heads up on what sort of generator you have been using? I will soon be starting my own build (if I ever finish the council paperwork!) and have no power on site. I've been trying to read up on generators but there are so many variables (inverter/non inverter, diesel/petrol/Watts and KVA) I really have no idea about electricity and what might be needed. I will need it mostly for power tools (just one at a time as it will be mainly just me working) and perhaps lights if working at night. Then I thought - if I am going to the effort of buying a generator - should I get the one that I will use as a backup for my solar system?
    I've also noticed you gas weld - I was looking at some 140amp arc welders (which is the method I've used most) but they seem to need HUGE amounts of power to operate so it oxy/acet best if on a generator?
    Any recommendations would be most welcome!

    1. Hi TC,

      My generator is a 6.5kVA diesel unit, China's Finest bought on eBay a couple of years ago. I didn't actually need it at the time, but knew that I would and spent a while watching various auctions to see what prices they were fetching, then jumped at the chance to pick this one up for about $650 if memory serves. Like all things eBay you have to read the fine print - although it's rated at 6.5kVA, that's 3-phase power (415V), and each of the three 240V outlets can only supply one third of that (about 2200W). It's not that big of a deal really - the only time I've tripped the circuit breakers on it is when I've been cutting the Hebel and labouring the circular saw hard. Most of the time the tools just run fine.

      The biggest challenge for me with this generator is that the starter motor is undersized for the engine, and it will not start the engine unless I use the compression-release lever (which allows the motor to spin freely and build momentum). This means I can't start it remotely (it has a remote control), neither will I be able to use it as a backup generator started automatically by the inverter/charger unless I sort that out. In addition, because I can only use 2200W at 240V per phase, I can't supply 6.5kVA as backup power because the three phases can't be wired up together. It's complicated :)

      If I was buying a generator again, I'd probably spend a bit more on a unit which can supply 3-4 kVA (roughly equivalent to 3-4kW; AC power is a little more complicated than DC) in one phase, so that it could supply that much backup generation capacity to the solar system. If I were you, I'd buy one generator that can serve you now and later as a backup unit. On the other hand, mine was such a bargain that it was hard to refuse :)

      As for welding, until last year I had never touched a welder of any sort, and my line of thinking was that since I'll always be on a power budget I may as well learn to weld with equipment that doesn't need any power at all! My oxy kit is a little Dillon / DHC 2000 / Cobra (it's changed names several time) which I've found to be really easy to use. Apparently these are popular in the custom / hot rod / panel scene, and since I plan to get into plenty of panel work once I can inhabit my garage, I figured this kit would suit me best and I was lucky enough to pick one up second hand (but unused) on eBay. Having said that, I've never used arc/stick, MIG or TIG equipment so I'm really not qualified to make a recommendation there. I am told that I'd be able to run a good MIG unit off my generator (I expect that would be easy if it were a 3 phase welder) and I don't doubt there'd be any issue running one off the solar installation with a good inverter. Certainly if you bought a larger single-phase generator you'd have no problems running an inverter welder on it.

      The biggest downside to oxy/acet welding is the cost of the gas and bottle hire. I'm paying about $80 a quarter for D-size bottles, and that much again for a refill. I do enjoy welding with it though.

      So no clear recommendations there I'm afraid but I hope I've helped!

      -- Simon

  2. Thanks Simon, I still need to do more research - but I think it makes sense to buy the main backup generator rather than one now and another later on. The more I read, the more an inverter generator sounds the go. Much more expensive but easier on the fuel and (apparently) a lot quieter. Re: the gas bottles - it bugs me that you cannot buy them! I hope to have gas boosted hot water and cooking so will have to rent those bottles - so think I will look into what arc welder I could operate off whatever gen. I end up getting.
    I love working with metal - the shed door you've made is looking good, can't wait to see them finished. Cheers, Terry