The finishing or spring tool should now be got and fixed in the same position as the roughing tool, water being used as before. Greater care must be exercised in sharpening, setting, and fixing, than in the former process, in order to secure the best possible finish. The callipers ought to be occasionally applied to ascertain the diameter of the work, and so prevent mistakes, while all vibrating must be stopped if possible. For long work, this is accomplished by the use of a backstay, which is generally fixed to the slide rest and moves with the tool. The finishing cut should be light and regular, so as to produce a good surface. After the first end is done, the unfinished one will be treated in a similar manner, the catch or carrier being moved to the other end, which will have to be protected from damage by a piece of soft metal plate, such as copper, placed between the finished surface and the carrier screw. Both ends have to be turned down quite square by means of a side cutting tool, but enough material must be left about the centre to prevent the work being thrown out before it is completely finished.