converting arc to TIG

Date 02-23-2004 04:51

A high frequency box is what you need. I put a Lincoln HF on my Linde arc welder. I also added a full wave bridge rectifier to get dc. I have some pics over at www.weldingweb.com. I think you have to join to see any pics. I am also going to post them on photobucket.com. Several firms made the HF boxes. They are basically a simple spark gap transmitter. Solar was one brand.

By 357max

Date 02-23-2004 05:40

This machine would be only rated for 70 to 100 amps ac for GTAW aluminum. The phenomenon is called dc component. The aluminum oxide acts as a rectifier and half (positive side) of the sine wave may go back into the machine as heat. There is no thermal overload protection on that ac machine and the extra heat will melt the insulation if it is used for long welds. The price the local distributor will sell a Miller high frequency unit is over 900 bucks. There is no remote amperage control capability and a secondary on/off switch is another 300. There may be cheaper ones out there. Or spend 1500-1800/1900 for Millers Econotig or Syncrowave 180.

By Mike W

Date 02-23-2004 07:37

I was aware of the rectification possibility when I built my setup. I installed a temperature guage on the welder with the probe bolted to the core of the transformer. I have seen it barely get off the low end of the scale a couple of times. I recently read some article about this taking place when you get above 200 amps but no reason for this was offered. I got my Lincoln for $250 I believe. I also added a scr control on the 220 input.