Post
by stenno » Sun Jul 12, 2015 10:49 am
Bottle rental is killer unless you have a hook up from someone that has a business of fabrication. Supagas, speed gas, machinery house etc do the buy / swap and go cylinders for around the $300 + 60 for a refill compared to boc $20 odd month rental but cheaper refills, airliquid has joined the buy cylinder game with an inbuilt reg on top of the bottle for $250 odd. Disposable bottles are good but heaps smaller, require a different adapter or different reg to work, and super expensive $50/60. Compare volumes in the cylinders v price, you don't need a 5 foot cylinder for occasional home use. I bet you could onsell the gas cylinder if you got a "buy/ swap & go" in minutes if you needed to cash out.
Welding like everything in life, fits into the once a year / weekend warrior / handyman / tradesman markets. Think eBay / gmc ryobi / makita / hilti or festool for power tools. There are exceptions to this too
Welders, I have a unimig 180, about $500, it's good but not great. Couldn't afford a Lincoln or fronus 180 $1000+ haven't used it with gas yet but gas less works fine for me just needs heaps more clean up of splatter around welds, think 1 foot around weld for repainting rather than centimeters. Also have a migomag (boc) 285 and remote feeder but no 3 phase power to run it.
Whatever you buy make sure it has an infinite adjustable power and wire feed adjustments, rather than fixed setting 1,2,3 etc. it's so frustrating not being able to wind back power just that "little" bit more but not a whole settling.
Welding helmets, any of the major brand auto darken helmets work pretty good once dialed in and cheapish without having to buy a miller elite digital. Good consistent lighting (overhead & movable floodlights) vs position of sun etc make more of a difference with your welding than 20 sensors vs 2 . I have a cig weld one because spare parts for it are available at nearly every hardware store around. Eg magnification lenses, gold filters, lense protectors etc.
If your having trouble seeing the weld "pool" with consistent practice conditions, lighting and position etc give these $10 gold lense or 2x magnification lenses a try by taping them to the inside of the helmet. It can be "eye opening" the difference they can make.
Spot weld drill bits as above, I haven't had much success with the holesaw type. I've had more success with a carbide burr in a die grinder for spot welds but you can make too big a hole easily.
Grinding down welds with the edge of a 1mm cutting wheel on a grinder reduces the heat affected zone/ warpage in the panel compared to a grinding or flap wheel. Just be careful you don't force it to flex the cutting wheel and then it shatters and bits fly everywhere in its path causing damage eg arms, face, car panels etc.
if your starting from scratch, consider a starter pack. Think of it like an apprentices first tool kit. Eg Lincoln ready-pak. It comes with helmet, gloves, jacket / apron pliers etc and usually an instruction dvd. They should be available from all the big names at a welding shop. Expect a big discount if you buy a welder from the same place..
Just remember practice makes perfect and fit up as good as you can make it will save 5x the time it takes in grinding and bridging gaps with welding.
Only weld clean metal unless your fixing a farm gate, the weld will be less porous = less likely to suck in moisture and then start rusting from inside out.
Brumby brand scouring wheel / pads are a god send for removing paint around where your welding compared to flap wheels, grinding disks and paint stripper and so much quicker too. Available at big green shed with 3 different grades but blue available at most hardware stores usually cheaper than bunnings too.
Upol copper weld through primer is the bomb but normal zinc weld through primer is still good.
Kill rust rust eater / converter and hd etch primer in a spray can are great for stopping flash rust after welding prior to full painting but you really need to seal / full paint within a week or two. Check if the top coat paint you use doesn't react to it too. Just in case
Sikaflex panel bond to seal any gaps. Used to hold Commodores together so it works.
Buy bondo / hi fill from a trade supplier rather than supacheap as the advice is far better and usually the price too. So much easier to sand down too.
If you get carried away and decide to respray the whole car, consider valspar lic40/43 or protec single stage "industrial" paints. They can be mixed to a colour you want, are cheap, require far less sanding for surface prep, don't need a clear coat and are self leveling which can mask a rougher surface prep / beginners paint skills better. Less need to a wet sand it. Approx $200 or less for 4 liters inc hardener and thinners. Often used on horse floats and trucks and semi trailers.
Cliff notes:
Practice makes perfect, but good fit up makes it easier.
Take your time / let panel cool to reduce warpage.
Any big name welders will be capable, panel welding is going to be sub 50 amps so no need for a fabricators spec welder. Just make sure it's adjustability is good not fixed.
Get a auto darken helmet that has good local parts support, lenses etc and easier to take back if faulty.
Gas bottles, search around for local dealers and prices v buy/ rent.
Expect the bottle to always empty Saturday just after every shop shuts. Murphy's law
Expect everything to take 3 x longer than you estimate
MIG with shielding gas is the only way if you aren't any good with an oxy set. Even gasless MIG is no good for panel steel. You'll want one with interchangeable wire feed rollers so you can use a thinner wire (.9mm way too big) I splashed out and got a multi process inverter (transmig 175i) but a cheaper transformer type would do the job, as long as you can dial down the power settings properly (the ones they sell at Funnings don't have enough control over the power settings) Cigweld do a range of machines that would be suitable, if you don't want to buy one new you could probably get one second hand. As for gas there are those tiny disposable bottles at funnings, but I've never used them. I just rent a bottle from BOC and be done with it but I know that's not for everyone. Don't weld in one continuous bead, just lots of small spot welds. Do a few at a time then let the area cool a little. And practice on scrap first! 
And although it's the "light" argoshield you can still use it on up to 6mm material which is all my machine can do anyway. Perfect for custom bull bars! 
