Advice needed from fellow builders

[baz-r]

the 160tm looks like it will take a proper gas bottle thats a bonus
find the spec's and look at the duty cycle ratings the higher the better

all have very simmular specs by the looks of it and you will realy struggle with the low duty cycles when you get to weld your chassis fully, do your rear uprights etc
if it has a duty of 20% at 130A that means at this power setting it needs 8mins rest (on so fan can cool it) to 2 mins of welding and so on any more than this and it over heats the transformer and cuts out and you have to wait ages for it to cool down also transformer effeincy drops badly as it gets hot

150A=10%
130A=20%
75A=60%
55A=100%

units that have all copper windings is what you need to look for as the dutys will be higher (will be real heavy). hobby gas bottles give low flow and realy work out to be expensive unless your just doing the odd job here and there.