PDA

View Full Version : tig power help



Samuel
04-17-2005, 02:12 PM
As you may remember from an earlier thread I was looking for a tig set up and I considered making one from and alternator/gas motor, buying a cheapie import, or piecing one together ie ac/dc stick machine/tig torch reg and tank. After a couple of months of looking I opted for the assemble the parts method, so now I have a working tig machine that uses an idealarc round top 250, no 17 weld craft torch hoses etc etc and sundry consumables, Smith flow meter, 250 cu ft. argon tank. so far I am into it around $300 total, which in my opinion is pretty cheap. now here is the "bad" news the lincoln idealarc 250 will not dial down below 30 amps, which is pretty hot for small and or thin stuff, as many tig machines will dial down to about 5 amps. what do I need to do/make to reduce the amperage ?

Thanks guys

Samuel

IOWOLF
04-17-2005, 06:14 PM
PLUG it into a 110 v outlet?

zl1byz
04-17-2005, 06:45 PM
<font face="Verdana, Arial" size="2">Originally posted by IOWOLF:
PLUG it into a 110 v outlet?</font>

No, sorry. It's current that you need less of not voltage. Doing that will drop the OSV on the welder, probably wont even be able to strike an arc with it.

I was wondering if a foot controler might be a way oround. It's a long time since I have used one. But usually you dial up the max current that you want on the machine and the controller gives the ability to adjust to currents lower. Can't remember if they do this in the machine or just add resistance to the welding circuit.

If it is the later it might work. If it ties into the machine, then probably still screwed.

John.

PaulA
04-17-2005, 10:48 PM
The foot controls work with some sort of control circuit in the machine. Now they use solid state stuff. In the old days (like my Miller 300) they used a magnetic amplifier - a special transformer that could limit the current in the main winding by running a small DC current through an additional winding.

You could probably build a constant current supply for use below 30A, but that's not exactly trivial.

Samuel
04-18-2005, 05:55 PM
thanks guys, I have been looking around for more info on how to get to the lower amps and I found ( but then promptly lost) a web sight that caters to tig welders kind of like someones home page , anyhow they sell a box that turns an ac welder into a tig machine and it had the lower amp range , have any of you seen this web sight?if you have let me know. by "You could probably build a constant current supply for use below 30A, but that's not exactly trivial." did you meen something like a smaller welder? and what do you think it would take?

thanks

Samuel

zl1byz
04-18-2005, 06:41 PM
Seems like might not be an easy way out of this one.

Might be that finding another machine that does the low amps, if that is what you need and send off the one you currently have.

Re inventing the wheel is not a great idea.

John.

snowman
04-18-2005, 07:07 PM
SCR

Dont know where I found this or if it even works.

http://photobucket.com/albums/v282/jrunyan02/?action=view&current=welderscrckt2gif.gif

-Jacob

snowman
04-18-2005, 07:08 PM
if you build that, make sure you ground your foot pedal controller.

there is essentially 240 volts in the pedal.

-jacob

3 Phase Lightbulb
04-18-2005, 08:26 PM
Samuel,

What thickness of material are you TIG welding where 30A is too much current?

Are you using 1/16" or smaller Tungsten Electrode? 1/16" 2% Ceria/ 1.5% Lanthanum/ 2% Thorium operating current range is 50-160amps.. .040" (1mm) electrode is 25-85 amp range... I assume you're using .040"?

You should have no problem welding at 30A unless your not flowing at least 20cfm of Argon... Make sure you're using ballanced A/C or DCEN (Straight Polarity/Electrode Negative)..

If you're still too hot, then move along faster.. You can still TIG weld using too much current, it just causes you to move faster and there is less room for error..

-Adrian