This section is from the book "The Manufacture Of Boots And Shoes: Being A Modern Treatise Of All The Processes Of Making And Manufacturing Footgear", by F. Y. Golding. Also available from Amazon: The Manufacture Of Boots And Shoes.
When two pieces of leather have to be overlapped they must be suitably skived. The skive,* scarfs or bevel varies with the conditions of each case. The idea is that the two substances, when joined, shall present the'appearance of one. In practice this would be modified according to the strength of the materials skived. Gene-rally, if the two substances to be united are equal in substance, the reduction by bevelling should be done on both. If a lighter material is to be affixed to a stouter, then the reduction would mostly be from the stouter. When skiving such portions as goloshes, care should be taken that no lumpiness is apparent on the inside of the upper. This will make it necessary to bring the portion underneath - we are here referring to a lap-joint - to a "feather " edge, while the edge of the overlapping portion must retain a sufficient substance to make a solid seam. The width of skive for seams should be nicely adjusted, so as to avoid any undue weakening of the seam. Where the vamps or quarters, etc., are not matched as to substance, it will be necessary to reduce the portions thicker than the others to a uniform edge.J The kind of skive made will be determined by its purpose. If it be only required to reduce the substance so that the overlapping portion may not be clumsy, and yet not weaken the substance materially for strength, then a bevel must be used that will be as illustrated by Fig. 185, where AB is removed leaving a proper bevel, without detriment to its supporting properties. The incorrect skive for the purpose of overlapping, seams, etc., is illustrated by CD in the same figure.
For "turning-in " § work a different sort of skive or derived from a timber-joint.
* Supposed to be derived from shive, a slice.
% An upper-leather splitting machine is often used to make the various portions of the upper of uniform substance, but the reduction here refers to the edges.
§ Some localities confuse this term with "beaded." The correct usage of the term leaded is reserved for the inserted "bead." scarf is desirable. The portion that is turned in should be of such a substance that when in position the main portion of the turned-in part should be together equal to the original substance of the material. This may be accomplished in two ways. The skive may be gradually brought to a "feather edge "in such a manner that when turned in it may, together with the leather of the body, be of the substance of the original. This kind of "turning-in "skive is illustrated by A and a in Fig. 186. It is the form of skive most adapted for hand turning-in. The other way of skiving for turning-in is shown by B and b in Fig. 186. It is the sort of skive most adaptable to "turning-in "or "folding" machines. The substance of the edge is not reduced to a feathered edge, which would cause a tendency to curl when being put to the gauge of the folding machine.
The skiving by the hand-process may be performed, either by pushing the knife away from the body of the user, or by drawing the knife during usage towards the person who skives. The former is used for turning-in, while the latter is more adaptable for materials of the nature of calf or kip. The skiving may be done by taking long, clean sweeps with the knife, or by short strokes or bites. The condition of the cutting edge of the knife and the texture of the material will determine which practice is to be followed. Generally, as long a sweep as possible should be taken. At any rate, the skive must leave the work uniform throughout its entire length. The skive for folded-in work should be twice as wide as the fold to be taken.
Skiving Machines are constructed on two principles. Those of the "Douglas "type are made with a fixed or stationary knife, against which the leather to be skived is delivered by means of the rollers. This class of machine is most effective on firm leathers, such as calf, split, kip, etc., but by careful operation certain dressings of calf-kid may be skived on this type of machine.
The Carver skiver is a useful machine for medium and heavy leathers.
For light, flexible, stretchy leathers machines with revolving knives are most effective. The best of this type is undoubtedly the "Amazeen." The old pattern is without knife-grinding attachment. The new model has, besides other improvements, a knife-sharpening apparatus. Fig. 187 shows this pattern machine. The new high-speed machine has an enlarged bevel gear, increasing the speed of the knife without making the guiding of the work impracticable. The cogs are also splendidly protected, minimizing accident to the operator. The added knife-adjusting screw and other improvements make the machine more easy of manipulation and adjustment.