TIG price too good to be true?

Yeah, no high frequency start, no AC for aluminum, no gas bottle or regulator. About 1/3 of a real TIG welder.

Well, if it's a transformer unit, it'd be too easy to hack inside and bypass the rectifier and choke. Install another jack and you've got AC and DC right there. You could also make an external HF start for a song.

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

Yeah.. but it comes with a shoulder strap, like a garden sprayer does. But that's a good way to keep the output cables short, I suppose.

WB ...............

It says it's an inverter.

Looks like you will be limited to DCEN, scratch start, fixed current while welding. The latter shouldn't be a problem for an experience TIG welder. Could be a real problem if you are just starting out.

In general, you get what you pay for. Availability of repair parts and labor could be a problem if anything goes wrong.

You will need a gas bottle and regulator. You ought to be able to cobble together a water cooler torch setup if you feel you need it.

The duty cycle could be a problem depending on the current you will be running.

On Mon, 17 Jan 2005 15:14:59 -0800, the inscrutable "Glenn" spake:

Shoot, if I'd thought about that, I would have had you pick up one of the 8-LED flashlights while you were there. They were on sale for $6.99 ending today, normally $9.99.

Newp, nothing shown on the link for that model.

Perfect. I'm not a very serious weldor. ;)

I may be tempted if this new client comes across with a downpayment check tomorrow.

Hmmm. How do you make a High Freqeuency generator? Are there plans somewhere in the dropbox or on the web? Would my stick welder benefit to make my starts easier? (to rephrase that.... would it be easier for me to start a bead without sticking the rod or getting it started through dirt / paint with an external HF unit?)

RWL

Larry, if you buy it and try it out, drop a note on sci.engr.joining.welding to let us know how it works out. I was wondering the same thing about this unit ... as well as the $499 35-amp plasma cutter that HF has on sale. Sure would be interested in how either works (or doesn't) ...

Or maybe a better deal is the imitation 2AA maglite for $1.99 that's on the back of catalog 308/2005. Item no. 03852. I see that even the web page has it for $1.99, so maybe that'll be the price for a while. BTW, I don't always get to the stores in time for them to still have sale merch. on hand, so I get a "rain check". Can usually wheedle the stuff out of whichever store I present the raincheck to.

On Mon, 17 Jan 2005 23:07:36 -0500, the inscrutable "Andrew H. Wakefield" spake:

It all depends upon a couple checks making their way into my bank account. One is committed and on the way, the other sounds promising. I'll let you know if I do find my crowbar and get the wallet out. Wow, a $500 plasma cutter, too!

On Mon, 17 Jan 2005 20:11:48 -0800, the inscrutable "nic" spake:

That's not an EIGHT LED light, now is it?

I do get rainchecks when possible. In this instance, I didn't get to the store during the sale, but I'll ask the manager for the sale price when I do get down there again.

Google Tesla coil, then build a small (100-500W) model. Only instead of a large secondary and flat primary, wind both as solenoid (uh, straight cylindrical winding like the original secondary) and use only a few turns of heavy wire for the secondary. Connect secondary in series with torch lead.

Not really, although I remember someone posted pics of the insides of his HF start unit (a professional model, but literally so simple a hand made device would have little lapse in quality).

I don't know. I'm going to build one to find out myself, I'll post when I do.

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

The Lincoln and Century accessory HF boxes are (or were) essentially a ferro-resonant transformer delivering about 8000 volts to a spark gap thru the primary of a fairly large (6" dia) air-core coil. This is actually a stepdown xfmr; the secondary is a couple of turns of copper strap delivering about 2KV at HF. I think there was a cap in there too. Note: these things generate a LOT of radio-frequency interference. They're legal, but they can make you unpopular.

The Lincoln (from Sears) I had was pretty good. The Century was utter crap. After examining it I returned it.

An electronic air cleaner supply (Honeywell, Trion, etc) would work well here. The voltage is about right and they're current limited.

If you're running DC, be sure you have a shunt capacitor (0.1 uF or more) and maybe an MOV on the welder side to protect the rectifiers.

Yes, it make starting a bead with an arcwelder much easier. The guy at the welding store told me that farmers love 'em. 7018, no sweat. Ditto paint, rust, mud, etc. (Shudder...) There's time for perfection after the crop is in, I suppose.

I'll look forward to your comments when it's done. Many years ago Century had an itinterant salesman that went from town to town putting on a welding show. They had an add on high frequency unit as part of the demo. The demonstrator picked some 13 year old boy from the audience and gave him the stinger, told him to push the rod into the work and asked him to try and stick the rod. It didn't stick. I never quite knew if it was a trick or whether it was the high frequency unit he was promoting. Like the figure skaters we competing on TV, the professional welders make it all look so easy.

RWL

| The Lincoln and Century accessory HF boxes are (or were) essentially | a ferro-resonant transformer delivering about 8000 volts to a spark | gap thru the primary of a fairly large (6" dia) air-core coil. This | is actually a stepdown xfmr; the secondary is a couple of turns of | copper strap delivering about 2KV at HF. I think there was a cap in | there too. Note: these things generate a LOT of radio-frequency | interference. They're legal, but they can make you unpopular.

I read that neon transformers are popular with the Tesla crowd, and I have read that solid state neon transformers use actual high frequency to create the high voltage, and they don't bleed on the AM radio band quite as bad. With a spark gap, can this work directly as a source? If there were a large, low inductance coil (like a coil of heavy solid wire) after the rectifier and before the spark gap, wouldn't that keep most of the HF out of the rectifier? I was working on trying to figure out what a good inductance was, but the size and practical aspects make it pretty hard to nail down actual figures on the inductor, so I'm guessing that pretty close would be good enough. I read about one idea on the web that had a coil of copper tubing with a dielectric and a smaller wire, actually making a heavy current coax, with the HF going through the center conductor and the electrode current going through the outer tubing. This was the transformer for the HF transfer. I imagine it would keep the radiated HF down to a minimum. Would these ideas be worth trying to run with?

Problem with that is it might be too high to use for a Tesla coil inverter, but is too low (20kHz or so AFAIK) to use directly. You need probably up around 1MHz.

It would, but inductors for handling 1. the high currents and 2. the high frequency are hard to come by, so you're better off just shunting it across the output with a small capacitor. You can put some RFC's on the primary side to keep crap radiated by the power lines down.

I figure you're never going to stop it, you've got to have at least a little radiated by the torch and maybe ground cables (and work) anyway, so you might as well put an HF pushbutton on it and use it just for starting.

Note that DC is done by adding a large inductor between the rectifier and arc, this will stop some HF on its own. The iron core and tight windings will still allow some to pass of course.

Interesting idea, but as long as there's HF in the system somewhere, there's going to be radiation. More of a question of TV and radio for five miles around, or just AM radio within a few blocks. I doubt you're going to kill TVs too many blocks away with just a few hundred watt NST supply.

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

Knowing what some of the farm equipment looks like and such - I figure a torch of one type or another burns off the paint - Then welding takes place.

I seem to remember my Uncle had a big torch - likely a cutting torch. And a stick machine of some sort. Uncle Art (first name) was in Dairy Cattle and farming. He did what was needed to get the job done. Easy as that. Not much deciding good or bad or whatever - just working and one we go.

Martin

Industrial welders for semiconductor and other in-place welding do use RF transformers. I used one in College. A spot welder in fact. One issue - RF burning.

But it works.

Martin