Tungsten Problem (?)

[idahoguy]

A friend has let me use his Lincoln Tig 300/300 (the later model, not the old timer) to practice on at his shop and we are having a problem in that the green tungsten won't form a ball. Even he can't get a ball to form. It does weld, but not as smoothly as it should. The arc can go along fine then it becomes finicky and wanders (looks like arc blow in SMAW). I'm practicing on clean (3M Roloc polish pads) 1/8 aluminium with 3/32 Weldmark electrodes using straight Argon at 15 cfh. I'm on AC mid-range, current range 7, with start "ON" (constant). I have no idea what those setting translate to in amps. The torch is a Weldcraft water cooled with a #6 collet (no gas lens). The ground is solid. I think the problem is in the electrode but even if I switch to a new one the problem again develops. Any ideas? Thanx

[shovelon]

A friend has let me use his Lincoln Tig 300/300 (the later model, not the old timer) to practice on at his shop and we are having a problem in that the green tungsten won't form a ball. Even he can't get a ball to form. It does weld, but not as smoothly as it should. The arc can go along fine then it becomes finicky and wanders (looks like arc blow in SMAW). I'm practicing on clean (3M Roloc polish pads) 1/8 aluminium with 3/32 Weldmark electrodes using straight Argon at 15 cfh. I'm on AC mid-range, current range 7, with start "ON" (constant). I have no idea what those setting translate to in amps. The torch is a Weldcraft water cooled with a #6 collet (no gas lens). The ground is solid. I think the problem is in the electrode but even if I switch to a new one the problem again develops. Any ideas? Thanx

Your HF(spark switch?) should not be on start, it should be on AC continuous. The switch should have 3 positions, start, on, and continuous(AC).

I bet the points inside the machine are shot now too. I would clean and regap your points, then put the HF on the correct setting and have another go.

Good Luck.

[shovelon]

I just pulled this manual and it is a bit confusing. I does mention something about failing PFC capacitors. You may want to have them checked.

http://www.lincolnelectric.com/asset...oln3/im349.pdf

[idahoguy]

Thanks for the quick responses. Pg 7 of the manual (IM349) says the "SPARK" switch should be set to "ON" for aluminium. I don't have the right equipment to check the capacitors and I know from my military experience that can be risky. Is that the case here?

[shovelon]

Thanks for the quick responses. Pg 7 of the manual (IM349) says the "SPARK" switch should be set to "ON" for aluminium. I don't have the right equipment to check the capacitors and I know from my military experience that can be risky. Is that the case here?

I believe it is rather simple. Like looking them over for damage and take a voltage reading with a volt/amp meter. But looking over the inside and blowing out is always a good idea.