The main shaft of a tap reseater is made from steel. This provides a strong base for all the other parts. Steel is hard-wearing and long-lasting.
Parallel bushings and tapered cones
The tapered cones are made from steel or brass and the parallel bushings can be made from either steel, brass or plastic.
All materials will do the job sufficiently, but the plastic parallel bushes are likely to wear out quicker and so are more suitable for infrequent use. The brass and steel varieties are more durable, steel more so than brass. Brass ones are cheaper than steel ones, but the durability of steel means it is usually used for professional tap reseaters.
The handle of the tap reseater can also be made from either steel or plastic. Handles in the form of a knob are plastic and are generally mounted onto an extension of the shaft. On the other hand, bar handles are made out of steel.
Tap reseaters with a plastic handle are slightly easier to hold as they have a better grip and shape. However, they will wear out quicker than the steel handles. This is why it is generally the DIY versions that have plastic handles, as they are not intended for extended use. The more frequently used, professional tap reseaters are made entirely from steel.
The cutters on tap reseaters are made from case hardened steel. This means the outer casing has been hardened but the centre remains soft, this is because completely hardened steel can become brittle. Therefore, the cutters are suitably hard to grind down a tap seat, but maintain a soft centre to absorb pressure.