A Manual of the Hand Lathe. Egbert P. Watson
the center.
Fig. 3.
To rough off the outside, and make it run true, is the first step, and the tool must, therefore, be held as in Fig. 3, or so that the point and part of the edge alone engage with the work. This will take off a thin, spiral cut, without springing the shaft or making it untrue. The whole surface of the shaft must be thus run over, beginning at the right hand and shifting the tool as fast as one part is turned. The tool should not be moved rigidly in a straight line toward the belt, but by holding it hard down on the rest, so that the bottom edge bears as in Fig. 2, and rocking the tool on that angle, so that the point describes a curve, as in Fig. 4, the work will be turned evenly and true.
Fig. 4.
We must remark, in passing, that the person who reads these directions, and then undertakes to turn by them, will find that reading how to do a thing, and doing it, are two different matters.
It looks very nice to see a skater darting over the ice at his ease, but try it once, and, if you never knew before, you will understand what experience means. Trying to teach a person to be a turner, in a book, is analogous. One can only indicate the general method, and leave experience to do the rest.
Fig. 5.
After the whole surface has been run over, the same tool may be used on the flat side for reducing the work to one diameter throughout the length. The reader must not assume that there is no other tool than a diamond point; he will find many others adverted to, as we proceed.
Fig. 6.
It is most important that the ends of a rod or shaft should be squared up first, before the body is turned, for the removal of some slight inequality subsequently may cause the whole shaft to run out of truth. The center must be drilled with a small drill, and slightly countersunk. When the end is squared up, the center must be run back a little, so that the tool point may project over the drilled hole, and thus make it all true about the center, as in Fig. 5. This will make the work push over to one side of the center, but that is of no consequence. Let it run as it will; so long as it does not come out of the centers there need be no apprehension.
Fig. 6, is another kind of roughing tool, to do heavier work with.
Fig. 7.
There are two kinds of tools used in foot lathes, called straight and heel tools. Fig. 7 is a heel tool. It is so called from the heel which is forged on the lower end. One form of the straight tool has already been shown. The heel tool is used on heavy work, and the object of it is apparent, namely, to hold on the rest, and so impose but little labor on the workman to retain it in place, or prevent it from receding. It is generally forged from half inch or five eighth steel. The steel is held in a handle twenty inches long, grooved on top to fit the steel, and furnished with a handle at right angles. This handle has a square eye in the top that the tool passes through. A nut at the end of it screws up the eye and binds the tool fast in the groove, so that it cannot slip.
It is given complete in Fig. 7. The lower handle enables the workman to have great power over the edge, and to direct it from or to the work without danger of catching. The tool is used by resting the end on the shoulder, as in Fig. 8, and turning the lowest handle. Since the heel holds the tool from slipping, there is no occasion to bear against it. In fact, there is no occasion, at any time, to force the tool from the workman, but it must be turned sideways, back and forth. A piece, properly centered, may be cut in any way without destroying its truth.
Fig. 8.
CHAPTER III.
SCRAPERS, ETC.
To suit different kinds of work, as previously stated, various tools are needed, but the reader must not expect to see them all illustrated in this book. The workman will learn what tools he needs, and make them for himself, which will be of more advantage to him than engravings could be. The tools here shown, will be found very useful in different places.
Fig. 9.
Fig. 9 is the end of a thin-edged, flat scraper, and is chiefly to be used on brass work. It may be of any length and size, but for small lathes, and light work, it is cheaper and handier to make it of thin sheet steel, one eighth or one tenth of an inch thick, and to form the reverse end into a round nose, or half-circle scraper.
Fig. 10.
It often happens that fillets or hollows occur, as in finishing ornamental brass work, in connection with flat surfaces. By having such a tool as this, the necessity of laying one tool down and picking up another, is obviated, for the two are combined in one. For iron work, it is customary to use a heavier and thicker tool for finishing. As in Fig. 10, the front edge is slightly raised or concave, to make it sharp and hold a cut well. All turning tools for finishing iron are made thicker than those for brass, and should have lips, or curved cutting edges. Such tools cannot be used for brass, as they are too sharp; the edges jump into the metal and spoil the work.
A tool for scraping brass work of some kinds is made as shown in Figs. 11 and 12.
Fig. 11.
Fig. 12.
There is no occasion to make the ends at different angles, except the convenience, before stated, of having four cutting edges on one piece, for any angle can be easily given by the position of the hand or the direction of the rest. These tools, here alluded to, are only to be used when the job has been all turned true and the scale removed; they scrape, merely, they do not cut.
Such tools sometimes save a few steps at a critical period; that is, when the tool is well set and in place, so that the work is done better and more expeditiously. Apart from this consideration, there is the chance of cutting or injuring the hands, by the proximity of sharp edges. Under the control of an expert, however, there is little danger from this cause, as inspection will show. Skilful men that have worked a lifetime at their trade, have few marks or scars on their hands, as a general thing.
When these scrapers are used on cast iron, or, indeed, on brass of a peculiar composition, they sometimes “chatter,” as it is called, and leave the work full of deep, unsightly marks, like those on the edge of coins. The cause of chattering is the rapid vibration of the tool, so that it springs away from, and against the work, with great rapidity, leaving traces of its edge on the work. Chattering may be prevented, by putting a piece of sole leather on the rest, between it and the tool.
The tools with long handles are chiefly intended for heavy work, or that which requires both hands to the cut, but there are smaller tools than these, used by amateurs, wherein the common file handle, or one like it,