Lumber recovery from a community – based timber processing mill using the ‘Logosol’ Machine

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In-situ chainsaw milling of logs is an important economic activity in Ghana since it produces about 80% of the domestic lumber supply. However, chain-sawn lumber production has been banned in Ghana since 1998 partly due to the large waste or residues associated with this operation. There is the need for an alternative in-situ processing method that improves lumber recovery. A study was conducted on the use of the ‘logosol’ machine which is a chain-saw (Stihl MS660) with attachments to determine its effects on lumber recovery for five Ghanaian timber species: dahoma-Piptadeniastrum africanum, esia - Petersianthus macrocapa, ofram - Terminalia superba, danta - Nesogordonia papaverifera and avodire - Turraenthus africanus. The objectives were to determine the milling recovery rates of these species and the time input for milling logs. The study also examined how common log characteristics (diameter and tapering) affect lumber recovery when using the logosol machine. The research was conducted in Gyaman and Gyapa communities in the Wassa Amenfi East District in the Western Region of Ghana. A total of 93 logs of the five species with volume 108.94m3 were processed into lumber using the logosol machine. The recovery was 51.71 m3 of sawn timber at an average recovery of 48.48 %, a rate substantially higher than the reported recovery (40 %) in chain-saw with free hand. The average lumber processing rate was 8.8 m3 /day of eight hours. This is also an improvement on chain-saw with free hand. An analysis of variance (ANOVA) showed that at 5 % level of significance, diameter and tapering had significant effect on recovery. It was only in dahoma and avodire that 25% and 36% respectively of variation in recovery could be explained by the tapering factor. In the other species tapering factor accounted for less than 8% of the recovery. Also the relationship between diameter and lumber recovery was weak for all the species (R2<25%) presumably due to the high incidence of defects on the logs.
A Thesis submitted to the Department of Materials Engineering (College of Engineering) of the Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the degree of Master of Science in Environmental Resources Management