[sausageroll]

Hi Everyone,

Just been watching Jodys video here about lap welding, and if you skip to around the 4.50 mark, you can see him do a pretty bad weld (for demo purposes) and then show the electrode. The electrode is shiny, clean and seems to look as though its been freshly ground.

https://www.youtube.com/watch?v=XIPx5Qx90VU

My question, this never happens with my set up... after the weld, the electrode is dull and grey, still with a point on the end, but by no means as clean looking as we see in this video.

The machine is a decent HF start with all the toys (made by a british company called R-Tech) I am using a gas lens (CK gas saver) and thorated tungstens. I am wondering if maybe I am using too small an electrode? In Jodys video he talks about 40-50amps, yet his electrode is clearly a lot bigger than what I would use for this type of weld (I would probably have used a 1.6mm electrode)

I am new to this, and largely self taught, so I am fully expecting to be wrong with what I am doing. If anyone could clarify if I am doing something wrong, it would be great to hear your input.

Pete.

[WTFH]

Your post flow is set to low allowing the atmosphere to come in contact with the still hot tungsten, turn it up and you'll be fine. You should set the post flow long enough to make sure the weld is shielded after welding so it will not be effected by the atmosphere, and the tungsten is sufficiently cooled too, which ever is longer.

[dsmabe]

I agree with the post flow. I have a Everlast PowerTig 185, and starting out with it, I had the same problem your taking about. I had to get used to the idea of using a lot more post flow, more for the tungsten than than the weld. Now at about 8 sec post flow my tungsten ALWAYS looks brand new!

[Artie F. Emm]

The GTAW Handbook from Miller suggests 1 second of post flow for each 10 welding amps... that always struck me as a bit of overkill.

[rick9345]

agree, post flow should last long enough to keep tungsten shiny.
PREFLOW also to have tungsten gas envelope established before arc starts
more time($) wasted redoing tungsten than the bit of extra gas flow ($)

[sausageroll]

Thanks for the suggestion, I will twist the post flow knob and see what happens. My flow is at about 5ltr/min (i think this is about 10.5 CFH)

Should I turn this up too?

Pete.

[AKweldshop]

Thanks for the suggestion, I will twist the post flow knob and see what happens. My flow is at about 5ltr/min (i think this is about 10.5 CFH)

Should I turn this up too?

Pete.

Yes,
More like 15 or 20cfh.

10 ltr/min.

[TwentyFourSeven]

This thread has been helpful. I never realized how important post flow was.

[dsmabe]

That's what I like about it here. Even if you're not new to welding, maybe just new to a specific machine, etc. there's a lot of great people here to help out.
With a plethora of information here we can always learn something no matter how long we've been at it!

[Wen]

I have (had) a bad habit of waving the tungsten around at the end of the weld. So post flow was being wasted. I learned to keep the tungsten stationary while the tungsten cooled. The post flow gas has to flow around the tungsten while it cools.

Took me a while to figure this out, and maybe everyone else already knows this, but thought I would add it to this thread.

[sausageroll]

Well I started with a cheap scratch start tig machine and the only way to stop the arc was to just take the torch away from the metal (or snap out) and so the elecrode was gray and tatty within one weld, and the scratch start process was really hard on the electrode tip so you very rarely got the electrode even staying sharp between welds (at least I didn't!!)

Anyway, I have turned my gas flow up to 20CFH (just realised today my flow meter actually has a CFH scale on it) and I have turned my post flow up to about 8 seconds.

See photos (please excuse the messy work shop, people like to dump stuff on my bench for some reason)

[motox]

maybe some tips here on jody's vid
http://welding-tv.com/2014/07/08/scratc ... -practice/