oxford / olympic welder help

[woodchip40]

i have just got bigger mig to the one i already had. it has extra knobs and things. no instructions so i wondered if any of you educated peeps could give me some guidance please ?
i was hoping to post a pic with this but can't see how to do it . i'll come back in a minute and add info of where the pic is, (hopefully)
oh good done the pics as attachments here.
what i know so far:
the red switch turns it on/off
the bottom big knob is the amps
the knob beside red swich controls the speed of wire
the top right knob changes the operation of the torch switch to permanent on.
that is all i know about the top two knobs: this is where i need help please.

 

[Robotstar5]

The top two knobs are probably for "spot timer" one sets the "weld on" time and the other the interval between welds. Turn them both to "0" for normal welding.

 

[Omniata]

The dial from "1" to "8" sets the voltage, not the amps
The amps are set by the wire speed...

MIG's are "constant voltage", Arc welders are "constant current"...


Could do with a new earth connector too

 

[Wedg1e]

The dial from "1" to "8" sets the voltage, not the amps
The amps are set by the wire speed...

MIG's are "constant voltage", Arc welders are "constant current"...


Could do with a new earth connector too

Ah, but current is voltage divided by resistance. As the resistance of the component to be welded is fixed, then changing the voltage must change the current - so turning up the 'Volts' switch turns up the Amps as well

E.g. resistance of part = 1 Ohm. At 12 V you'd have 12/1 = 12A. Switch up to, say, 24V and you now have 24/1 = 24A...