Page:Turninglathes.djvu/15

 The bed of a Lathe is usually made of two bars in a single casting, planed quite flat on the top and edges. It may be of beech, mahogany, or hard wood, but it is now so easy to obtain complete Lathes of iron, and they are so cheap and convenient, that it is not worth while to build them up at home. In some of the small Lathes, there is no crank axle, but the flywheel is hung upon a short bolt or stud, which screws into the left standard. The crank is then merely a pin fixed into one of the spokes of the wheel. Standing on the bed are two poppets, or, as they are also called, headstocks. The one on the left hand is permanently fixed in place by a strong bolt and nut. This headstock carries a small wheel or pulley, the axle of which is the mandrel. The pulley is turned with grooves for the Lathe cord; that of smallest size giving the greatest speed. This is used for wood, and the slower motion is for metal. Soft wood, like deal, needs the quickest speed of all to make it cut clean. The harder woods, and also bone and ivory, are usually turned at a slower rate.

The mandrel is the most important part of the Lathe. It is made generally with the conical neck passing through a hard steel or gun-metal collar in the headstock, while its other end rests on a hard, pointed screw of steel, which is called the tail pin. By means of the latter, any wear of the neck or collar can be taken up by screwing the tail pin so as to push the mandrel neck forward into its collar. This must always be attended to, as the mandrel must turn very easily, but without the least shake. There are oil-holes drilled in the top of the headstock, and lubrication must never be omitted. The best sewing-machine oil should be used, and a few drops of paraffin will make it still more suitable. Never use vegetable oil, like linseed or olive, Lucca or colza, if it can be avoided. Sperm oil is good, either alone or with paraffin, and if only olive or salad oil is obtainable, always add paraffin to it, as it materially improves it. A good lubricant makes a surprising difference in the running of a Lathe. The crank axle screws, and also the crank hook or chain, must also receive due attention in this respect; likewise, now and then, the bearings of the treadle.