Normally I don't get involved in these threads but here goes,
Yes I am a boilermaker by trade (but that makes me no expert)
Yes I own a fabrication shop that does mig welding of mild steel, aluminium and stainless steel (more so the mild steel and that still does not make me an expert)
Yes I do a little tig welding manly my own items (still not one)
Aluminium tig can be not so difficult to do if you follow a couple of steps
Number one is clean material must be clean and like painting most of the work is in the preperation
Right gas for the job Argon for tig welding of aluminium and stainless
Right tungsten for the job (differs from stainless to aluminium)
Most blokes out there can weld stainless tig if they can oxy weld (oxy welding of steel is not that easy), the only other problem with aluminium tig welding is controlling the amperage when welding and also the molten pool as with aluminium the pool does not change colour (unlike steel), also with the heat transfer the job can soon get very hot and you will find you have to much amperage so always best to pre-heat your aluminium jobs and start with a lower amperage as it is easier to control.
Mosts castings on bikes will have a aluminium alloy base of magnesium (the more magnesium the lighter it is) and things of a structural nature more silcon based alloys as straight aluminium is very soft and of little structural use.
Welding machine wise I am not going to comment on as it will depend on the amount of use you need it for and the type of welding you do but with aluminium welding you need a machine with HF (high frequency) that keeps the arc from job to the tungsten on AC welding. We use a Kemppi brand machine that are good but are very dear to buy.
I would think the man with the most knowledge on this would be Geoff Morris as he does it day in day out.
Shane
