tungsten size

[Fazerruss]

Good evening all, Im new to this forum. I recently bought a Marshall Dynabolt tig welder (same as a Miller Dialarc HF250) and im nearly ready to start having a play with it. Im a complete novice when it comes to tig so i have a few questions. One of my first jobs I want to do after some practice is fabricate an inlet manifold for my lotus 7 style car I am building so I want to know what is the Ideal size of tungsten for welding 10mm ali?
The welder is a transformer based machine and I have read that when welding ali in ac mode you should use a larger diameter pure tungsten electrode but how big?
Also when welding different metals do you still use only pure argon?

This is my new beast of a machine, well new to me!

Cheers
Russ

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[shenion]

The miller TIG calculator will tell you the recommended tungsten size:

http://www.millerwelds.com/resources/calculators/tig_amperage_calculator.php

You use pure argon for all metals. Argon/Helium mix can also be used for added heat but it is expensive.

 

[dannyp]

pure argon.

forget the pure tungstens they are hard work you want the ones with the gold band they take a lot more abuse

 

[Shox Dr]

1, Min of 2.4mm

2, Yes

3, Welcome

 

[langy]

1, Min of 2.4mm

2, Yes

3, Welcome

X2, if your new to TIG I would start with steel and get the hang of that first