homemade tig using an arc welder

[superls]

all,

this is sort of a development tool off the back of the inverter based ac tig im currently designing, it will be sort of a test bed for things.

ive acquired an ark welder, ive also managed to scrounge a parweld 4m tig torch off a mate that needs the switch replacing.

ive read articles on the net that say people have used an ark welder with a tig torch as a basic dc tig, afterall most dc tigs have acr capability anyway.

however my question lies here, not many ark welders as ive seen have hf start there mainly scratch start. ive done a bit of readign and as i understand it hf start is just a squirt of high voltage high frequency, to create an ark.

ive looked into how this can be done and stumbled accros the link below.

http://www.casano.com/projects/hfstart/index.html

imo the theory seems suported, but i wanted to know if anyone had done it before, or used anything similar to it before, or does anyone have any betters suggestions.

how it is done commercialy?

cheers scott

 

[voipio]

These devices, improperly designed, have a habit of getting the Ofcom interference branch knocking on your door fairly rapidly, since they're capable of generating quite a bit in radio frequency interference. Ofcom's direction-finding capabilities are quite impressive! The circuitry of the box described in the link is broadband, with no attempt to generate the RF within one of the ISM (Industrial, Scientific, Medical) frequency allocations, which would be the preferred option. This box will knock out am, shortwave, fm, dab, and TV, to boot, plus emergency comms, for some distance, and emcomms especially, since they rely on weak signals a lot of the time.

Voi

 

[superls]

yes but i would have thought in a properly screened and shielded metal box it should be fine?? however rf is not one of me strong spots.

 

[voipio]

A shielded box will screen some of the RF generated by the boxed components, but there would still be a transmitting antenna plugged into it i.e. the torch lead, plus an operator loosely coupled to that via hand capacitance.

This circuit would generate a wide spectrum of RF energy with a peak, which can be "tuned" by appropriate choice of tank loading capacitor to coincide with an ISM band, but there would still be plenty of energy in the "skirts" and the peak would quite easily drift out of band.

Voi