joint. Tube being hollow, it's not practical to use a simple punch operation to notch it, as it would be squashed. Although punching is possible, it requires support mandrels and awkward handling. Where tube is worked with a punch press other than for side notching, this is generally described as slotting. Tube notching for fabrication of circular tube is thus most commonly done with a rotary hole saw in which a hole saw of the diameter of the tube being attached to is fed into the stock to be notched at a semi-perpendicular angle. This produces a semi-circular notch. Rather than using large presses, such saw notching may only require a simple jig, also making it suitable for on-site working. A much more accurate way of notching the end of tube stock is to use a specially made milling cutter called an end mill. The stock to be notched is clamped into a vise and can then be fed slowly and accurately into a rotating, hardened metal, end mill. The equipment required for this method is considerably more expensive than the hole saw method and does not lend well to the same portability of the hole saw method as the machine is usually bolted to the floor for stability and safety reasons. This method of end notching is much faster and thus greatly minimizes the chance of damaging the stock either by warping due to heat build up or by squashing as can still happen with a hole saw. Notching in thin-wall tube may also be carried out by abrasive tools, reducing some of the risk of damage from a hole saw snatching. This also allows more complex shapes to be performed, such as vee notches. In some cases, a helical end mill cutter may be used. Computer numerical control (CNC) notching is enabling designers to work with more complex geometries. Notch and bend Vee notches in tube, particularly square tube, may be cut so deep as to cut almost through the tube: three sides of a square tube. This then allows torner, usually finished by welding. On a smaller scale for jewellery making, this operation is performed by hand-filing precious-metal strip before bending and soldering to make box frames or stone mounts. References Fabrication (metal)