CK17 Accessories FAQs
Answers to common questions about TIG torch accessories: consumable kits, gas lenses, cups, switches, cable covers and looking after them safely.
What is a gas lens kit and why would I use one?
A gas lens is a special collet body and cup that holds a fine mesh screen. The screens create a more uniform, smooth flow of shielding gas, with less turbulence than a standard collet body. Because the flow is more even, good gas coverage can usually be achieved with less gas, and it is often recommended for critical or high-quality welds.
It also allows the tungsten to extend farther than a standard collet body does, which helps with access to joints.
Gas lens parts must match your torch family and tungsten size, and the best settings depend on the job, so test on scrap first.
How far should the tungsten stick out of the cup?
There is no single figure. Stick-out depends on the cup size, whether you use a gas lens, the joint access and the gas flow. With a standard collet body, the usual guidance is to keep the tungsten extension within the inside diameter of the nozzle. A gas lens allows the tungsten to extend farther than that.
Keep stick-out as short as the joint allows, because more stick-out makes gas coverage weaker. A longer nozzle gives the gas more room to settle before it leaves the cup.
A stick-out gauge helps you set it consistently. Follow your torch maker's guidance and your welding procedure.
How do I choose the cup size?
Use the correct tungsten and cup size for the joint. A larger cup gives a wider, longer smooth column of gas and better shielding, so choose the largest diameter and longest length that the joint will allow. Smaller cups suit tight spaces or small parts, but they raise the gas velocity, which can cause turbulence.
Cup sizes are commonly numbered, so check the sizes your torch family accepts and make sure any gas lens uses matching cups.
It helps to keep a few sizes to hand so you can change cup to suit the joint and the current.
What gas flow should I set when I change cups or fit a gas lens?
There is no universal setting. TWI quotes around 15 litres per minute as a general figure for gas shielded processes, but the right flow depends on the consumables and the surroundings, and the advice is to use the lowest effective flow for the job. Too much flow causes turbulence and can draw in air, while too little leaves the weld and the hot tungsten exposed to the air.
A flow meter regulator placed close to the power source gives a more accurate reading.
For your torch and cup, follow the maker's guidance and your welding procedure, and check results on scrap.