The New Zealand Railways Magazine, Volume 2, Issue 11 (March 1, 1928)
Lathe v. Grinding Machine
Lathe v. Grinding Machine.
The re-turning of an axle or the re-boring of a cylinder involves the removing of more metal from either than would be necessary if the same operations were done on a grinding machine. This is due to the fact that a worn axle or cylinder develops a hard skin, which necessitates that before any progress can be made with the tool, the turner must take a cut sufficiently deep to get under the skin. Afterwards a second (or finishing) cut is necessary.
The grinding machine functions equally well on hard or soft metals, therefore, when re-grinding an axle or cylinder witness marks may be left in, and only the bare minimum of metal removed. This produces a smoother and truer surface, adds considerably to the life of the parts that have been thus treated and creates a big saving in regard to renewals, etc. Furthermore, the grinding method has proved conclusively that, re-grinding, apart from these advantages, is also quicker than re-turning.