Implementing Lift-arc TIG welding technique?

I think they run enough current through the contact sensing arrangement that there is an arc started when the electrode is lifted, but small enough not to melt anything until the increased voltage associated with electrode lifting is detected and the current is ramped up to whatever the setting is. Perhaps on the order of 1 to 5 amps. You will not be able to do this with your planned approach since it is the welder SCRs and their control circuitry which will be regulating your current, not your H-bridge. And why would you want to, you have high freq starting assist, you don't have to touch the work at all.

What sort of welding are you planning to do, and what kind of torch, gas and electrodes do you have?

Oh, I see. Yes, messing with that would be difficult.

All kinds of stuff, I suppose, for projects "around the house" and such. I want to make a nice rock tumbler. I have a WP-20 torch that is water cooled, and use straight argon. Have various kinds of electrodes, but not many.

So far, actually, I only practiced stick welding, and am quite impressed with just what can I do with stick.

Here are some of my stick weld beads

i

Good point. I have a grinding station with grinders, chop saw etc, on casters. I can (and do) drag it out of the garage to grind heavy stuff or to cut steel. I would do the same for grinding electrodes. Tungsten's boiling temperature is very high, so I am not sure how much radioactivity would be released by welding. In any case, I will definitely keep this in mind.

i

Look out for the thoriated electrodes (red tip where I bought them). They are radioactive. After I tried some near my Geiger counter, I decided not to use them for welding any more (especially not without good fume extraction).

Chris

Go to the US Patent & Trademark site and search for patent number 6,034,350:

Click on the Images link to view schematics. You'll need to install a free TIFF image viewer if you haven't already.

Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com

"I'm not grown up enough to be so old!"

Keith Do the images for that patent open for you? All I get is a generic image icon on the web page and nothing else. By "TIFF image viewer" do you mean a stand alone application like Irfanview or am I missing some kind of plugin?

I don't recognize the number, but water cooling is the only way to go above 80 amps or so, and argon is all most TIG requires.

Looks like you are starting to get the hang of it, one of your beads is almost even. You will probably find that TIG is easier than stick. Suggest you get the hang of TIG before modifying your welder.

Haha. Thanks anyway. :)

Yes, definitely, I will do just that.

i

It's a plugin:

Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com

"I'm not grown up enough to be so old!"

Thank you for prompting me to try something new.

I tried some corner welds today. The story and closeup pictures, with welds sawn off and destructive testing performed (all pictured):

I will make a separate post to sci.engr.joining.welding about this.

i

Wayne Cook Shamrock, TX

First thing I notice is that the 7018 weld is cold. 7018 needs more current than most rods so you have to turn it up compared to 6011 or

6013. I usually run 1/8" 7018 around 120-125 amps adjusting slightly for metal thickness.

You also ran a little slow for that thick of metal from the looks of it. Some practice on the flat with 7018 like you've done with 6013 would help this some.

It does look like you improved toward the end of the weld. Some more practice would probably improve it greatly.

Wayne Cook Shamrock, TX

Thanks Wes

Thanks Keith.

Free Patents Online will give you a PDF of almost any patent with the images.