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Backcap Long (with O-Ring) 3 Series, Torch Head Accessories, Gas Saver Parts.
Practical answers on choosing, fitting and looking after the individual parts of a larger gas saver torch set-up.
Usually not. Collets, bodies, insulators, back caps and cups are made to fit one particular torch series, and parts from a different series, or from a standard set-up without a gas lens, often will not thread together or seal properly. Even a part that seems to fit can leave a small gap that lets air into the shielding gas.Match every part to the torch series given in the torch manual or marked on the old part. When several parts need replacing, changing them as a matching group is the safest way to avoid mismatches.
The heat shield sits between the gas lens body and the cup. Its main job is to help seat the cup and seal the joint so shielding gas cannot escape or air be drawn in, and a missing or wrong insulating part can contaminate the shielding gas. Check the torch manual for exactly what it does on your torch.Torch makers list separate heat shields for standard, short and large diameter gas lens set-ups, so they are not normally interchangeable. Inspect it whenever you change the cup, and replace it if it is cracked, crumbling, distorted or no longer seats the cup firmly, because a poor seal can let air into the gas.
The O-ring seals the rear of the torch head so shielding gas cannot leak out and air cannot be drawn in. Heat and repeated tightening and loosening can make it dry out, crack or flatten.Signs include a visible crack, a flattened or pinched ring, or porosity and discolouration in the weld that you cannot trace to gas flow, draughts or cleanliness. Use an O-ring that matches the cap and torch series, check that the groove is clean, and seat the ring so it is not pinched as the cap goes on. If in doubt, fit a new O-ring whenever you replace the back cap.
These are two separate choices. A standard collet is slotted and is squeezed onto the tungsten as the back cap is tightened. A wedge collet is a single piece with an angled end that presses against the collet body, and it is usually described as more durable than a slotted type.Stubby (short) describes length. A shorter collet normally goes with a shorter gas lens body and helps access in tight joints, while a standard-length collet goes with a standard body. Lengths differ between makers, so confirm the collet suits your lens body and tungsten diameter before choosing, and check the torch manual if the fit is unclear.