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| Time Required to Heat Veneer Bolts and Flitches http://www.chat-place.org/forum/viewtopic.php?f=30&t=39757 |
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| Author: | longknifes [ Fri Sep 22, 2017 7:12 am ] |
| Post subject: | Time Required to Heat Veneer Bolts and Flitches |
That is, less splitting occurs during Nose Bars, tightly cut veneer than when handling loosely cut veneer. In addition, heated knots are softer and result in less knife wear than cutting similar wood from unheated blocks. Grantham and Atherton (25) conclude that heating does pay when cutting veneer for plywood to be used in construction. Time Required to Heat Veneer Bolts and Flitches Most investigators agree upon some points about the time required to heat veneer bolts and flitches, but other points are controversial. First, let us examine the points that are generally accepted. 39 Generally Accepted Points Uniform Final Temperature The bolt or flitch should be heated long enough so that temperature of the wood from the start of cutting to the end of cutting varies no more than 10° F (6° C). To achieve this goal, the heating time must be sufficiently long and the heating medium (steam or hot water) must circulate freely to all surfaces of bolts and flitches. Effect of Diameter The time required to heat a large-diameter bolt or flitch is much longer than the time required to heat one of small diameter and generally increases with the square of the diameter. For example, while a bolt 1 foot (0.3 m) in diameter might be heated in 14 hours, a bolt of the same species 2 feet (0.6 m) in diameter would require about 60 hours. This example is from the report by Fleischer (20) for wood having a specific gravity of 0.50, an initial wood temperature of 60° F (16° C), a temperature of the water used to heat the bolt of 150° F (66° C), and the final temperature at a 6-inch (15 cm) core of 140° F (60° C). |
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