glad i made ya laugh... that was the point!
heres another silly electrical lesson.
one a 110 v welder the duty cycle would be about (lets say) 20%. The most likely reason would be the fact that the tiny little transformer in it is going to get hot from the arc- essentially a short circuit. SO, the more you weld, the more heat builds up and the less current will be able to pass through the xformer. Its a simple fundemental of electricity. The hotter the device gets the more its resistance goes up and the less current it will be able to pass. So bigger Xformers can handle more heat for a longer period of time, but they too will eventually over heat.
when they overheat, the windings can burn and lose their varnish insulation and then BZZT! no more welding ever... or other things like the core laminations can seperate and then the xformer is noisy and most annoying... like that one floro light at the back of the shop... uhg.. If i recall correctly, there is also a point at which the xformer magnetic field will not get any bigger..its a limitation of the device itself. the core has a specific permiability, the windings as well have some limitation that i can longer remember.. " you can only put a gallon of water in a four quart pail..."
if you need power, there is no other cure than to go big(ger).