Well my problem in brief is that when i use the foot pedal on my machine ( a German made ''stahlwerk AC/DC'' TIG 200A) the max amperage is controlled by a rotary knob on the foot pedal itself (or i think so). The instant amperage is indicated on the machine display.The knob had a very crude division ffrom 1 to 10.
Now lets say that i want to set my current to a max of 80A ...its impossible since i don't have a reference point. The display might indicate the current but i cannot observe the display while i am welding !!!
My first try was to measure the travel of the rotary knob , design an indexing panel with 0-200div ,print it on a sticker sheet and stick it around the knob.
Well it looks good but...the amperage control is way off
Any help ???
The pot's on Chinese welders are rarely linear so it's trickier than it first looks - my suggestion is hold the pedal down full travel with amp knob on min & note display setting - then increase slowly every 10 amps or whatever division you want & mark onto periphery of knob with a line - if you want you could then create a sticker after establishing the fact as Oscar suggests - or once your used to welding leave the knob full power & let your eye / foot / puddle reading skill adjust as need be - almost never had the luxury of a display or working display on what I get to use ! - if it's code work with a narrow window of current in a WPS that would be different.
Konstantinos, if your machine will only indicate amperage while actually welding, you can set up the torch in a vice at an appropriate distance from a piece of heavy scrap, and set up a shield to protect you from the arc. You can then mash the pedal, adjust the dial, and read the machine's stated amps while it's actually "welding". Be sure to move the scrap around a lot, or otherwise give it time to cool as you're building an index of knob positions versus amps.
noddybrian wrote:The pot's on Chinese welders are rarely linear so it's trickier than it first looks - my suggestion is hold the pedal down full travel with amp knob on min & note display setting - then increase slowly every 10 amps or whatever division you want & mark onto periphery of knob with a line - if you want you could then create a sticker after establishing the fact as Oscar suggests - or once your used to welding leave the knob full power & let your eye / foot / puddle reading skill adjust as need be - almost never had the luxury of a display or working display on what I get to use ! - if it's code work with a narrow window of current in a WPS that would be different.
That is a very good idea !! you are right it is definitely not linear , i will write down the new actuall measurements
Otto Nobedder wrote:Konstantinos, if your machine will only indicate amperage while actually welding, you can set up the torch in a vice at an appropriate distance from a piece of heavy scrap, and set up a shield to protect you from the arc. You can then mash the pedal, adjust the dial, and read the machine's stated amps while it's actually "welding". Be sure to move the scrap around a lot, or otherwise give it time to cool as you're building an index of knob positions versus amps.
...my two Drachmas...
Steve
Thank you Otto i will probably do it this way , i might borrow a clamp meter from a friend in order to confirm the machines readings .
Is it possible the amperage to vary at the same knob setting ? varying from electrode diameter or if it is AC or DC ?
In this case i might have to do this check 2 or 3 times.
Bisdremis K. wrote:...Is it possible the amperage to vary at the same knob setting ? varying from electrode diameter or if it is AC or DC ?
In this case i might have to do this check 2 or 3 times.
It shouldn't vary AC versus DC, since the controls are digital, but I can't rule it out. A simple check would be to pick three positions you've already sorted out in DC, one each at the low end, midrange, and top end, and compare actual readings in DC versus AC. The amperage setting should not care what size or type tungsten you are using, and should not vary with the electrode to work distance unless you set that very high, which you will never do in actual welding.
I was just mentioning it in case it wasn't a matched set. Different brands use different resistances on the controls. So if it wasn't specifically for your machine it's possible it's the wrong ohm resistance. You can verify if you know what pins on the connection are for the resistance pot. Then check it with a good meter.
