To Make Long Cuttings From Lumber – Rip Character - Marked Low - Grade Yellow - Poplar First By Philip

Long, character-marked furniture cuttings are easily obtained when low-grade (2A and 2B Common) yellowpoplar lumber is first ripped into strips and then crosscut to remove objectionable defects. Overall yields of character-marked material using this procedure were 78 % from 1 Common and 2A Common and 70% from 2B Common yellow-poplar lumber. Furthermore, 82% of the 1 Common cuttings, 61% of the 2A Common cuttings, and 35% of the 2B Common cuttings were longer than 50 inches. INTRODUCTION Tradition has called for clear grade cuttings in fine hardwood products. But as high-quality lumber continues to become more expensive, furniture, kitchen cabinet, and other manufacturers must examine the potentials of lower grade lumber. There may be opportunities to include more of the natural’ ‘character marks” in wood (presently called defects) in exposed cuttings. Recent surveys by the American Walnut-Fine Hardwoods Association have shown that consumers prefer character-marked furniture over clear grade furniture. Acceptance of charactermarked quality products is important because it opens the door to use of the less expensive and more abundant lower grades of lumber. We define character-marked cuttings as cuttings that may contain, on the exposed face, minor defects such as stain, small bird pecks, small burls, pin knots, and pinworm holes. The reverse or nonexposed face may contain defects of a sound grade that do not impair the strength of the piece for the use intended. Character-marked cuttings are currently used in exposed surfaces in painted furniture and cabinets, as core material, and as panel edge banding material. Hardwood products require mediumand long-length cuttings (30 to 90” long) as well as abundance of shortlength cuttings. To determine how well these cutting size requirements could be satisfied with lower grade lumber, several samples of yellow-poplar lumber were processed into character-marked cuttings with a gang rip operation as the first processing step. In the second processing step, gang-ripped strips were defected, producing randomlength character-marked quality cuttings. These cutting lengths were then compared with those needed for furniture and kitchen cabinet exposed parts. Gang ripping was done first, instead of the traditional crosscutting first, because it yields similar quantities of parts more easily, produces longer length cuttings more readily, and can be highly automated (Lucas and Araman, 1975; Araman, 1978). However, to use the rip-first system effectively, a manufacturer must (1) produce standard width parts and/or (2) glue cuttings into panels and then rip parts from the panels. THE STUDY Character-marked cuttings were made from 1 Common (lC), 2A Common (2AC), and 2B Common (2BC) 4/4 yellow-poplar lumber. Two 500-board-foot samples of each grade were ripped into strips of specific widths. One sample of each grade was ripped into 2.25” strips, and the other sample was ripped into 3‘’ strips. Wide edgings generated during ripping were saved for processing into cuttings. The 2.25” and 3‘’ widths were selected because earlier work showed high overall yields in strips and wide edgings when ripping of widths from 1 to 3‘’ was simulated (Araman, 1978). Also, we wished to confirm our earlier finding that the narrower width resulted in longer cuttings. An important objective of most gang ripping processes is to produce glue line quality surfaces on the sides of the cuttings. To assure a glue-line edge from gang ripping, relatively straight boards are required. Therefore, all boards with crook in excess of 5/16 inch over the total length were crosscut in half before ripping. Some crook was so pronounced that the boards were crosscut in half again. The lumber was then gang ripped, using a 7/16-inch hogging head cut on the leading edge. Saw blade width was 3/16 inch. After gang ripping, the objectionable defects (i.e., those too large or not classified as character marks) were identified and the lengths of cuttings between these defects were measured (Fig. 1). Wide edging material that contained at least a 1-inch wide cutting (after the rough edge was removed by ripping) was similarly measured. Yield of cuttings and length distributions for the cuttings based on their surface areas (length x width) were then calculated. THE RESULTS Length of cuttings. The distributions of cutting lengths Reprinted from FURNITURE MANUFACTURING MANAGEMENT, Vo/ume 1, Number 10, December, 1979 ORIGINAL BOARD WITH OBJECTIONABLE DEFECTS STRIPS AND EDGING FROM GANG RIPPING EDGING TOO NARROW TO USE CUTTINGS LOCATED BETWEEN DEFECTS Fig. 1. Gang ripping an 8.5-inch by 10-foot 2C board to 2.25-inch wide strips and removing objectionable defects to produce from the six samples after gang ripping 2.25and 3-inch strips are shown in Figures 2 and 3, respectively. Character-marked cuttings from 10 to 194 inches long were obtained. The cuttings from the 2.25-inch test using 2AC lumber were found to be uniformly distributed between normal (10 to 49 inches), long (50 to 89 inches), and extra long (90 to 194 inches) cutting length groups. The 2AC cuttings from the 3-inch test had more normal length cuttings. About 50% of the lC cuttings were in the extra long group; in contrast about 65% of the 2BC cuttings were in the normal cutting length group. Even though most of the 2BC cuttings were normal length, there was still an abundance of long and extra long cuttings over 50 inches long. Boards halved due to crook. Additional long length cuttings could have been obtained if the lumber had been straighter. Sixteen percent of the lC boards, 15% of the 2AC boards, and 29% of the 2BC boards had to be crosscut in half to remove excessive crook (over 5/16 inch deflection) so that a glue-line edge could be cut on the leading edge of each board. Furthermore, 5% of the lC halved boards, 19% of the 2AC halved boards, and 1% of the 2BC halved boards had to be crosscut in half again. Ripping width comparisons. Yields, when 3‘’ strips were ripped, were similar to those for 2.25” strips (Table 1). However, the average length of character-marked cuttings was about 11” longer when the narrower strip was used. Ripping the narrower strip also generated fewer edgings, thus fewer narrow edging cuttings. With the 2.25” strips, about 1 out of 10 cuttings came from edg ings, but almost twice that amount came from edgings with the 3‘’ strips. Lumber grade comparisons. Yields from lC and 2AC lumber were similar, but the 2BC lumber yielded about 7% less material (Table 1). Average cutting lengths decreased markedly as grade went down, but the average cutting length from 2BC (around 40 inches) is still significantly long. The percentages of cuttings that came random length cuttings. (For illustration purposes, acceptable defects are