The Wood Turner's Handybook - A Practical Manual for Workers at the Lathe: Embracing Information on the Tools, Appliances and Processes Employed in Wood Turning. Paul N. Hasluck

      CHAPTER II.

      HAND-TOOLS USED FOR TURNING WOOD.

      THE wood-turner who works at the foot-lathe employs but few edged tools except chisels and gouges. By the aid of these alone nearly all external turning is done.

      Economy of time is essential to the economic production of work, and it is, therefore, in some cases, advantageous to roughly round the material to be turned before putting it between the lathe centres, as there are ways of doing this at a less cost than by turning. In speaking of cost, it is here used in its abstract form, and means value of labour irrespective of the time employed; and if two unskilled hands can do more work than one skilled workman receiving double the wages, it would of course be cheaper to employ the two hands. Balks of wood may be trimmed up to a cylindrical shape with a hatchet, a paring knife, or a draw knife; and large chips of superfluous material are hewed off by these means quicker than could be done on the lathe, with a less expenditure of technical skill, and with appliances far less costly. Thus there are many reasons for getting material roughly to shape before mounting it in the lathe. For the same reasons the centres of such balks should be marked, and so obviate delay in finding the centre when chucked, though a general and very good plan is to finally centre the work as the turning progresses, for it is only when the rough, irregular figure is turned that its hollow places can be determined with certainty; and when the turning has reached the stage at which this shows itself, the work is driven, by blows of a mallet on its full side, to run so that the hollow will come up to the tool.

      The cutting edges of tools used for turning soft wood are found to act best when ground to an angle of about twenty-five to thirty degrees. This gives a keen edge, capable of withstanding the ordinary usage of such work. To work with tools which are ground less acutely is like cutting wood with a cold chisel—and here it is as well to explain that a cold chisel is the name by which chisels used for cutting cold metal are known.

      There is a great deal in keeping the tools in a proper condition for work; and the turner has to learn this, even before he begins to learn turning itself. New tools require to be ground and set before they can be used.

      Cylindrical work, both plain and ornamental, is first roughly turned to shape with the gouge, and then the chisel is brought into requisition to smooth and finish the work. The same description of tools are employed for turning flat surfaces, both plankways and endways of the wood. Hollows and internal recesses are also turned with gouges and chisels whenever there is sufficient space for their introduction.

      The correct position for the cutting edge of the tool is at a tangent to the circle which it is turning—that is, the circle left after the passage of the tool; and it is only necessary to thoroughly understand the meaning of this to be able to place the tool with precision and certainty in the best possible position for cutting. A tangent is a line which touches, but does not cut into the circumference of a circle, and the chamfer ground on the convex side of the gouge has to form a tangent to the circumference of the diameter being turned. It must be perfectly understood that a tangent may be formed at any point of the circumference, and equally well at the highest or lowest point. It is generally said that the height of a tool should be exactly of the same height as the lathe centres, and though this is perfectly correct in the case of slide-rest tools as usually ground, yet the axiom has no bearing if applied to hand tools, though in turning metal the same rule is advisable, as it affords a rigid rest at the most convenient place. No matter at what height the rest is fixed, the tool can be placed at a tangent to the work by elevating or depressing the handle as may be required.

      To make the action of turning tools clear, so far as their cutting edges are concerned, I will borrow from “Lathework” a diagram which shows two tools correctly applied for cutting both soft and hard material. By this it is seen that the slide-rest tool, with a strong cutting edge suited for operating upon highly cohesive metal, such as steel, and the acute wood-turning chisel, suited for the softest material, have each the lower face-angle placed in the same position with regard to the work. The upper face, which wedges back the shavings, curling or breaking them according to the nature of the material operated upon, is the only one in which any difference is observable agreeable to this latter condition.

      In Fig. 13 the line of centres is shown by a, b. It is precisely to this height that all slide-rest tools should be set. With hand tools it is of little importance whether they be applied above, below, or on the line of centres. The edge of the metal-turning tool is formed by the meeting of the faces a, x, and d, x; d, x is three degrees from the perpendicular, and this gives the angle of the edge as eighty-seven degrees. The edge of the soft wood chisel is formed by the meeting of the faces c, x and d, x enclosing twenty-five degrees, still keeping the lower face in the same line, that is a tangent to the circle.

      Suppose the tool is laid on to a true cylinder, so that its bevel forms a tangent to the cylinder, it cannot cut the material; but directly the handle is raised the cutting edge is depressed into the cylinder, and all that material lying outside of the diameter of the edge is removed. The position of the cutting edge is best determined by the sense of touch, the tool being laid on the T rest with its end overhanging the work considerably. The lathe being in motion, the tool is then drawn gradually towards the operator, all the while keeping it resting on the cylinder, till the edge reaches the point at which it forms the tangent, and then it commences to cut. By slightly tilting the tool, the edge is brought to act on a smaller diameter, and turnings are removed under the most advantageous circumstances.