How to Bend a Copper Tube
– Types of bending tools
– Step 1: Locate the bend to be made
– Step 2: Insert the tube into the bending machine
– Step 3: Bend the tube
Although there are small and large radius 90° bends and prefabricated curved fittings in standard diameters, it is often better to bend the pipe itself. This avoids 2 welds (one at each end of the fitting) weak points in a heating or sanitary distribution system. This is particularly important when the circuit is subsequently concealed behind a lining, in a false ceiling or under a false floor.
Here’s how to bend a copper tube.
There are two copper tubes, depending on whether the metal is annealed or hardened.
– Annealed metal is sufficiently malleable to be shaped by hand. This is what is done at first to uncoil it, as it is sold in coils. The result is never very aesthetic, but that is not important because it is intended to be embedded or hidden.
– Hard drawn metal is rigid. It is sold in perfectly straight “bars”. This tube cannot be bent directly, or it will pinch and break. It must first be heated quickly (with a single gas torch or a welding torch) to anneal it at the location of the bend to be made. The bending itself is done with specific tools.
There are 2 types of tools for bending: the spring and the bending pliers.
The spring is slipped onto the tube and allows the tube to be bent without lateral deformation. The spring must correspond precisely to the diameter of the tube. Therefore, it is defined by 2 numbers (inner diameter × outer diameter). Example: 14 × 16 (for 16 mm tubes).
– Advantage: the price.
– Disadvantage: lack of precision (no indication of angle).
Using a lever, the tube can be bent up to 180° on its fixed (semi-circular and graduated) jaw. The bending pliers (also known as benders) are fitted to the tube. Like the spring, the bending machine must correspond precisely to the diameter of the tube. There are, therefore, several models. This tool is also available in a box with interchangeable jaws in the manual (crossbow) or electric versions.
– Advantage: precision (thanks to the angle indications).
– Disadvantage: the price.
Good to know: to make bending more effortless, you can anneal the copper, i.e. quickly pass the area to be turned under the flame of a torch (or a soldering lamp).
1. Locate the bend to be made
Use a felt-tip pen to mark the boundary of the bend to be made on the pipe, i.e. where its straight section begins.
Important: depending on the bending machine, the mark may have to correspond to the beginning of the bend. Consult the tool’s manual.
2. Insert the tube into the bending machine
– Fold the bender lever forward: it should now be in line with the stop on the left.
– Now thread the tube along the stop provided for this purpose.
– The mark on the bender lever should be slightly behind the mark on the bender lever.
3. Bending the tube
– Place the concave part of the tool against your right or left knee.
– While holding the handle and tube in your left hand, gradually pull the bender lever towards you with your right hand.
– As you bend, the mark on the tube will gradually advance towards the mark at the end of the bend on the tool. Check that they coincide at the end of the operation.
– Then, extend the lever backwards to release the tube from the bending machine.
Good to know: first, it is not easy to position the tube correctly the first time, so it is best to bend it gradually.