Out in the Tool Shed
by Vic Shattock
The Miniature Locomotive, Jan-Feb 1954, Page 22
The sketch of the piston is intended to show an easy way to making this feature steam tight. Many live steamers feel that metal expanding rings are the only thing to use; on the other hand many live steamers have found that metal rings have their disadvantages, particularly on small bore cylinders up to 1-1/2" diameter. L.B.S.C. has written many articles relative to the use of packing in small pistons and I have followed his advice for many years when I build small locos. My only purpose in these notes is to point out that there is a packing on the market know as Garlock valve stem packing No. 170. It can be obtained in diameters of 1/16", 1/8" and 3/16" or larger if necessary but the three first named sizes will most likely be found suitable for small steam pistons. It is a close braided asbestos material and a ring can be cut and placed in the piston groove or, grooves, as the case may be, and will last for years if given the lubrication ordinarily furnished by a mechanical lubricator. this packing absorbs the oil, consequently it has a little of this essential item in reserve should the lubricator fail for some reason or other during a run thereby saving the cylinder walls or pistons from being scored.
Try it some time but use this particular brand as it has been proved not only on small locos but in large installations to be the right thing for the job. I would suggest that before cutting the grooves in the piston that you have a piece of this material on hand so that the grooves may be cut to suit, as the sizes may vary a little, either over or under.