2582 Chapter 22 



Equipment to turn and sand squares and other shapes is shown in figures 18-175 

 through 18-190. 



The economic feasibility of hardwood dimension manufacture is examined in 

 sections 28-4, 28-8, and 28-13. Consumption of hardwood lumber used to 

 manufacture furniture in 1960, 1965, and 1977 is graphed in-figures 29-26 and-- 

 29-27. 



Edge-glued core stock. — Core panels, a class of dimension stock, are used 

 as center fill material for laminated products. High-grade lumber core cuttings 

 for use in tops, shelves, doors, and drawer fronts can contain only minor defects 

 such as stain, small bird pecks, small burls, pin knots, and pinworm holes 

 (Araman 1978). Yellow-poplar has traditionally been favored in manufacture of 

 such cores. 



Araman (1978) observed that in recent years, yellow-poplar has become 

 abundant, especially in the lower grades. Because of this increase in availability, 

 continued use of yellow-poplar as furniture core material should be assured if 

 cost of the lumber core is maintained or lowered. Failure to control cost will 

 result in loss of the furniture core market to other materials, principally particle- 

 boards and fiberboards. 



From his analysis of alternative production procedures, Araman (1978) con- 

 cluded that 2A Common lumber is the most economical grade when converting 

 low-grade yellow-poplar lumber into furniture core material; ideally, a combina- 

 tion of 2A Common and 2B Common lumber should be used. In the most 

 economical manufacturing procedures, narrow strips from a gang-ripping oper- 

 ation are sent to a defecting station where objectionable defects are removed by 

 crosscutting. From this point, one of two procedures should be employed, as 

 follows: 



• Each random-length, defect-free piece is cut to the longest needed length 

 that the piece will yield 



• Or, resulting random-length pieces (minimum of 8 inches) are sent to a 

 finger jointing station where the ends are machined and glued to yield a 

 continuous strip which is then cut to required lengths. Finger jointing 

 results in a loss in usable length of about 7/8-inch per joint; because edges 

 must be remachined prior to edge gluing into panels, this procedure also 

 results in a width loss of about '/s-inch. 



With either system, Araman found that yield from 2A Common lumber is about 

 70 percent when cutting strips 2.25 inches wide. 



A persistent problem in panel manufacture is sunken glue joints, caused by 

 surfacing the panels too soon after gluing. The wood adjacent to the joint absorbs 

 water from the glue and swells. If the panel is surfaced before the excess 

 moisture is distributed, more wood is removed along the joints than at intermedi- 

 ate points. Then during subsequent equilization of moisture, greater shrinkage 

 occurs at the joints than elsewhere, and permanent depressions are formed. 

 These depressions are visible on the surfaces of veneer laminated to such cores. 



