Guidelines For Grading Hardwood Logs
Eugene M. Wengert and Dan A. Meyer
University of Wisconsin, United States Department of Agriculture, and Wisconsin counties cooperating. UW-Extension provides equal opportunities and programming, including Title IX requirements. No. 74 February, 1994 Guidelines For Grading Hardwood Logs Eugene M. Wengert and Dan A. Meyer INTRODUCTION TO USFS GRADING RULES Almost all sawmills purchase logs based on both log volume and log quality. Processing high quality, large logs costs less per board foot of lumber produced, and yields a larger percentage of high grade lumber, than does processing smaller or lower quality logs. Higher grade lumber with lower costs means higher returns; thus, a mill can afford to pay more per board foot of volume for larger and/or higher quality logs than for smaller or lower quality logs. The log grades presented here were developed nearly 50 years ago by the USDA Forest Service (USFS). The three log grades in the USFS grading system are No.1, No.2 and No.3 – sometimes called F1, F2 and F3, with “F” standing for factory. Most logs will fall into one of these three grades. Two additional “qualities” are also often encountered: a higher grade called “veneer” and a lower grade, “cull.” Neither is included in the USFS factory log grading system nor are they discussed here. The USFS factory log grades – No. 1, No.2 and No.3 – are quite close to the individualized, independently developed, log grades used in many mills in Wisconsin and throughout the East and South. USFS grades, however, offer several distinct advantages to the sawmill: 1. The grades separate logs of the same size by at least 20% in value. 2. The grades allow easy estimation of lumber volume yield by NHLA grade, based upon log size and USFS grade. 3. With price information, value yields for different log sizes and USFS grades are easily computable. 4. The USFS grades provide a basis for a mill to compare its yields from different sizes and grades of logs to actual industry standards. This paper further explains the potential benefits which can be realized using the USFS hardwood grading rules. The rules are described and illustrated, and grading procedures are explained in detail, including the definitions and treatment of log defects. IMPORTANCE OF USFS GRADING RULES The primary intent of developing the USFS grades was to provide at least a 20% value separation between logs of equal size but different grades. This value separation allows the buyer a certain confidence in knowing what to pay for logs. In other words, the buyer knows that a No.1 log is at least 20% more valuable than a No.2 log, which is at least 20% more valuable than a No.3 log. The value separation arises because different grades of logs produce different grades of lumber. For example, consider a red oak log 16 inches in diameter and 16 feet long (Table 1). Regardless of its grade, the log will produce roughly the same total volume of lumber. However, the volume of lumber in each grade, and therefore the total value of lumber produced, will vary with the log grade. Guidelines For Grading Hardwood Logs, page 2 Note: Another useful rule of thumb available with USFS log grades is that No.1 logs will yield 60% or more of No.1C and Better lumber; No.2 logs will yield 40 to 60% of No.1 C and Better; and No.3 logs will yield less than 40%. (Lumber grades referred to are standard National Hardwood Lumber Association grades.) Table 1. The average grade and value of lumber produced from 16-inch diameter, 16-foot long red oak logs of three different grades. Log Lumber Produced Grade FAS & Sel No.1C No.2C No.3C Total Value bd ft $ 1 90 45 34 13 182 173 2 40 64 44 29 177 140 3 12 44 53 56 165 103 Based on $1225/MBF for FAS and Sel, $875 for No.1C, $550 for No.2C, and $360 for No.3C Another major benefit of using USFS log grades, and one which is especially valuable with today’s small profit margins and high log costs, is the ability to quickly and accurately estimate the volume and value of lumber a log will yield based on its USFS log grade. Following the development of the log grades, formulas were developed to predic
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