Straight answers to the questions people ask most when choosing and looking after a TIG torch.
Do I need an air-cooled or a water-cooled TIG torch?
Air-cooled (also called gas-cooled) torches are lighter, simpler and cheaper, because the shielding gas flowing through them does the cooling. They suit lower currents and shorter welds. Water-cooled torches have a coolant circuit and stay cooler at higher currents, so they are the choice for thicker material and long, continuous welding, but they need a water cooler and extra hoses.
If you mostly weld thin to medium material in short runs, air-cooled is normally enough.
What do numbers like 9, 17 and 26 on a TIG torch mean?
Many TIG torches follow standard series designations, with numbers such as 9, 17 or 26. They show the size of the torch body, and so roughly how much current it can carry and which consumables fit it, although the number itself is not an amp rating.
The real current rating also depends on whether the torch is air- or water-cooled and on how long you weld without a break. Check the maker's rating and choose a torch above the current you will weld at.
Which tungsten electrode should I use?
For most work on steel and stainless steel with DC, a ceriated or lanthanated tungsten is a good all-round choice: it starts easily, lasts well and holds its shape. For aluminium with AC, zirconiated or pure tungsten is the traditional choice because it forms a small rounded tip, although many modern machines also work well with other types.
The colour band on the electrode shows its type, but colour codes differ between makers, so check the packaging. Thoriated tungsten is still seen, but it is mildly radioactive, which is why many welders now choose other types.
How do I prepare and grind a tungsten?
Grind the tungsten lengthways, so the grinding marks run along the electrode towards the tip rather than around it. Use a wheel kept just for tungsten so it doesn't pick up other metals, and use eye protection and dust extraction, because the dust is a hazard.
A sharper point gives a more focused arc, which suits lower currents and fine control on thin material. A blunter point copes better with higher currents and is less likely to melt back. Leave a tiny flat at the tip, and keep to the same shape once you have a setup that works.
What does the cup number mean, and which size do I need?
The number on a TIG cup (nozzle) is the size of its opening in sixteenths of an inch, so a larger number means a wider cup. The cup must be wide enough to cover the weld pool with shielding gas, but not so wide that you waste gas or can't see or reach the joint.
Larger tungstens and higher currents generally need a larger cup, and a gas lens allows good coverage with a smaller cup. Ceramic (alumina) cups are the usual choice, and clear glass cups let you see the weld better.
What is a gas lens and is it worth having?
A gas lens is a fine mesh in the torch that smooths the shielding gas so it leaves the cup as a steady column rather than a turbulent stream. That gives better protection, so you can often use less gas, and it lets the tungsten stick out further for a better view and for reaching into awkward joints.
It is a worthwhile upgrade for stainless steel, aluminium and any joint where you need extra reach.