Lathe Peeling or Full Round Rotary Slicing In rotary sl […]
In rotary slicing, a whole round log is mounted on a lathe and turned against a veneer knife blade. Rotary cutting or “peeling” of a log produces a continuous sheet of veneer as if the tree were a roll being unrolled. It is the most economical method of cutting. Veneer cut this way varies in pattern as it cuts through the successive layers of growth rings. Rotary cut veneer can be wide enough to produce full-sheet (single piece) faces. This method, however, does not lend itself to creating matching faces, due to the inconsistency of the grain patterns.
This method of cut is also used for very exotic woods like burls and uniquely figured species like, bird’s eye maple, sapele pommele, and macore mommele. In order to achieve veneer sheet sequences, we score the log or burl at one point. This produces sheets that begin wide and gradually get narrower as the veneer knife blade cuts closer to the logs and burls heart.
For all veneers that will not be rotary sliced, the logs are sawn into halves, thirds, or quarters or more.
With half round slicing, a half, third or quarter of a log is attached to a plate on a lathe and turned. This method adds width to an otherwise narrow log by increasing the radius of the cut. Half-round slicing is used to accentuate the variegated grain in certain woods. However, it can also be used to achieve a flat- or plain-sliced veneer appearance.
In plain slicing, the most common process for fancy veneer manufacturing, a half, third or quarter of a log (the flitch) is mounted on the vacuum flitch table with the heart away from the veneer knife blade. The cut is then made with the blade parallel to the length of the log. Flat slicing or plain slicing produces consecutive leaves of veneer and produces the standard appearance of veneer (the “cathedral” or flame shaped arch) that exemplifies plain sliced cherry, ash, oak and other species. This cut of veneer is ideally suited for wall panels, doors and furniture because of the consistency in its grain, and the ability to match sequences of leaves.
In order to achieve veneer with a very straight grain, quarter sliced veneer is often specified. The quarter of a log is mounted on the vacuum flitch table so that the growth rings are perpendicular to the cutting blade. Quartered leaves are cut consecutively, are narrower than plain sliced, and are easily matched. This cut requires the largest diameter of logs. However, quartered white oak is often sliced specifically for its appearance of a distinct “flake” marking – which is actually created by the veneer knife bisecting prominent radial patterns in the tree, called medullary rays.
Rift slicing also achieves a straight grain pattern, but avoids the appearance of “flake” that occurs in some species when quarter sliced. Rift slicing uses a “stay log lathe,” which cuts with a rotary action. A quarter of the log is fixed to a plate on a turning stay log. As the flitch is rotated, the veneer knife blade and angle can be varied so that the wood is cut exactly to produce the very straight rift grain. Most often, this method is used with oak. Other species such as rift-cut maple, walnut and cherry can be specified to be rift cut to achieve wider sheet widths. Since rift grain is generally the straightest and free from cathedrals and variations in grain, it is used to enhance verticality, and is easily sequenced and matched.