Tungsten tip shape

I see very detailed descriptions as to how the tip of the TIG tungsten rod should be ground.
Whatever I do to the tips lasts only a minute at most before the tip melts
into a nice ball and thatΉs the shape it wants to stay in, it seems.
So what's the deal with the shape, how does it stay that way, for me it seems like carving ice cream, a fleeting experience at best...
Uwe
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Jaggy Taggy wrote:

What are you welding, and with what settings ? On aluminium and AC, it should be a ball anyway.
Steve
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wrote:

give us little more info amigo :) what type of tnugsten, what size? what amprage? what type of metal are you welding? AC or DC welding? what type of shielding gas?
if you are welding with A/C the tungsten will ball up
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On 11/8/05 10:39 AM, in article snipped-for-privacy@4ax.com,

I think your questions guided me already in the right direction, I went back to the books and I am making progress.
Thanks Uwe
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So?? What did you discover that helped the tips stay nice?? When I use DCEN the tungstens seem to "swell" and get grey/oxide looking. I have yet to have one stay shiney. The ground point distorts rather rapidly also.
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wrote:

same question as above :) the only thing we know is that you use DC. if your tungsten is turning grey it is over heating. use larger diam tungsten. more shielding gas (post flow) general rule is 1 sec postflow per 10 amp. with water cooled torch it is a bit less. I assume you use air cooled torch, the shielding gas flow is the only thing that cools that red hot tungsten.
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I didn't specify amps as it seems to happen at anything from about 10 amps on up to 130. I have both water cooled and air cooled torches. The machine with the water cooled torch is a Dialarc 250 with an HF TIG head to control the water and gas. The aircooled machine is a Harbor Freight inverter DC TIG box. The harbor freight has the postflow tied to the current dial some how as it gives a fairly short pf with the knob all the way down and longer with it all the way up. I have to manually adjust the flow on the dialarc. In either case it seems the tungstens turn grey and frosty and seem to swell. After a very short use they won't pull back through the collett. Neither the current nor the size and type tungsten seem to matter. I still get the strange swelling. I have tried both gas lens and standard cones also. Could it be I am holding too long an arc? I tend to keep pulling the torch back for some reason and find the arc sometimes over a 1/4" long. How do you know if the tungsten is overheating while welding and what can you do about it?
I got the engine project that has been bedeviling me for months out of the shop this weekend so perhaps I will have more time to play with the welders again.
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