Articles containing the keyword 'tukit'
Category : Article
At three Finnish match factories 1,629 aspen logs were measured (see Kärkkäinen and Salmi 1978). When the estimation was based on the condition of the butt cross section of a log, less than half of the logs were sound without any discoloration or decay. Based on the condition of the top cross-section, the corresponding figure was a little higher than 50%. The logs with decay were bigger than those without it. There were relatively more butt logs among the logs with decay than among the totally sound logs.
The PDF includes a summary in Finnish.
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Kärkkäinen,
E-mail:
mk@mm.unknown
In this study the area, 8 diameters, and 16 radii were measured of 174 discs representing aspen logs in a mill. The average difference between the largest and smallest diameter was 18 mm, or 7% of the longest diameter. The difference between the largest and smallest radius was 29 mm, or 22% of the longest radius. The diameter was on the average 2.4 mm longer than the two corresponding radii.
The exact area of each disc was measured using a planimeter. In comparison, the area based on the circle formula the diameter being the arithmetic mean of largest and smallest diameters overestimated the area by 1.7%. The results also indicated that the use of random direction in the measurement of diameter overestimated the cross-sectional area on the average by 1.8%.
The study is continuation of the earlier study where the bibliography is presented. As far as the results are comparable, they support each other.
The PDF includes a summary in English.
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Kärkkäinen,
E-mail:
mk@mm.unknown
The aim of the study was to determine the extent to which the cross section of birch (Betula sp.) and aspen (Populus tremula L.) logs differ from a circle and to test some simple methods for measuring the cross-sectional area which can be used, for instance, for determining the volume of the logs. The material consisted of 420 debarked birch disks and 240 aspen disks which were representative of the logs arriving at two factories.
The convex deficit values for the material were very small, the cross-sectional area error being in general less than 1%. On the other hand, the other parameters deviated from the circular form to quite a large degree. It was also evident that the radii measured from the piths to the surface of the wood varied considerably more in the same disk, as regards length, than the diameters measured in different directions.
It was evident that the shape of the average cross-sectional area was not in general elliptical. It thus appears that any method for measuring the cross-sectional area which is based on elliptical formula is not suitable. The method which gave the best result was that in which the cross-sectional area was taken as the average of the area of the circle calculated from the smallest diameter and that calculated from the diameter passing at right angles to it. This method also appeared to be the best for disks which deviated to quite a large degree from the circular form. The suitability of this method is increased by the fact that the relative error is only slightly dependent on the size of the disk.
The PDF includes a summary in English.
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Kärkkäinen,
E-mail:
mk@mm.unknown
The present paper presents studies on the influence of some relatively common defects of Scots pine logs in Northern Finland on both the sawing yield and on the quality of the sawn goods. The study was based on test sawing of 25 logs for each of the defects (upright limb, heart shake and various kinds of wounds and scars) at Karihaara sawmill. The yield was graded into grades used for export timber according to the system of the sawmill. The proportion of the different export grades (U/S), fifths, sixths and culls) were used as characteristics together with the ratio of raw-wood consumption expressed as cu.ft/std.
Upright limbs occurring in a piece of sawn timber was shown to lower its quality to fifth grade in 43.5%, to sixth grade in 46.8% and to the category of culls in 6.5% of all cases. Only 3.2% of the cases the piece remained in U/S-grades. The size of the upright limb was the most important factor lowering the quality and affecting the ratio of raw-wood consumption.
Heart shakes are relatively common defects in pine logs deriving from over-mature trees. The quality-decreasing influence on the sawing yield depends clearly on the length of the shake in the cross-section. The same characteristics also decreases the ratio of raw-wood consumption. In addition, twisting and star shakes are considerably more harmful than straight ones. If rot occurs in connection with shakes, the places marred by the shakes are only capable of yielding sixth-grade sawn goods or culls.
Scar encountered in logs affect the sawn yield and its quality to quite a varying degree, but these defects themselves may also vary considerably both in size and quality. The length of the scar is highly significant as a quality-decreasing factor. If, in addition, rot is encountered, the defect is of a severe nature.
The PDF includes a summary in English.
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Heiskanen,
E-mail:
vh@mm.unknown
Silva Fennica Issue 69 includes presentations held in 1948-1950 in the fourth professional development courses, arranged for foresters working in the Forest Service. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.
This presentation discusses accuracy of the quality grading of Scots pine (Pinus sylvestris L.) saw logs suggested by professor Ilmari Vuoristo based on a data collected by Valtiala. According to the study, greatest inaccuracies in the grading by visual inspection was caused by differences between the evaluators.
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Heiskanen,
E-mail:
vh@mm.unknown
Silva Fennica Issue 69 includes presentations held in 1948-1950 in the fourth professional development courses, arranged for foresters working in the Forest Service. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.
Quality grading has been rarely used in pricing of saw logs due to lack of knowledge on how the quality of logs affects the value of the sawn wood. This presentation discusses the subject based on unpublished data professor Ilmari Vuoristo collected in 1930s on effects of timber grading on the quality and value of sawn wood. The quality classification developed by professor Vuoristo is presented.
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Heiskanen,
E-mail:
vh@mm.unknown
Silva Fennica Issue 69 includes presentations held in 1948-1950 in the fourth professional development courses, arranged for foresters working in the Forest Service. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.
This presentation describes benefits of the qualitative classification of saw logs to forest owners and forest industry.
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Heiskanen,
E-mail:
vh@mm.unknown
Silva Fennica Issue 69 includes presentations held in 1948-1950 in the fourth professional development courses, arranged for foresters working in the Forest Service. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.
This presentation describes the uses and principles of different kinds of grading of saw logs.
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Heiskanen,
E-mail:
vh@mm.unknown
Silva Fennica Issue 69 includes presentations held in 1948-1950 in the fourth professional development courses, arranged for foresters working in the Forest Service. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.
This presentation describes the grading of sawn timber for export and domestic use, and suggests improvements to grading of the sawn products in the saw mills to better answer the needs of export.
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Siimes,
E-mail:
fs@mm.unknown
Silva Fennica Issue 69 includes presentations held in 1948-1950 in the fourth professional development courses, arranged for foresters working in the Forest Service. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.
This presentation describes the development of standards for timber grades in Finland, and the present quality grades of raw timber for timber sales from state forests.
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Pöyhönen,
E-mail:
vp@mm.unknown
Category : Article
The aim of the study was to find out the ratio of raw wood consumption and the quantity and quality of the sawing yield using circular saws. The unit of study was one single log, the Norway spruce logs were divided into two grades and Scots pine logs in three grades. The principal material of the study was collected in 1950-51 using four types of saws of type EKA-50. The data consisted of 1,690 logs.
On the basis of the material, the efficiency of centre-piece sawing was 63.9% of the technical volume. On the average, 32.1% was unsorted goods, 11.5% fifths, 19.1% sixths and 1.2% culls. For spruce, the efficiency was superior to pine, which means that the consumption of raw wood for preparation of one standard of sawn goods is smaller in spruce than in pine. The volume of side boards trimmed reached about 2% of the total log volume. The efficiency of sawing and the ratio of raw-wood consumption were calculated both on the basis of the estimated and actual volume of trimmed goods. The raw-wood consumption is particularly good in logs of small and large top-diameter.
Goods sawn with circular saw have a characteristic shape. They are thinner at the ends than in the middle parts, and the deviation from the correct measure is larger in the first than in the last end of the pieces. They are also wedge-shaped because of the first piece sawn is thinner than the second one. The deviation from the correct measure exceeded the allowance for shrinking in seasoning. The goods are often under sized even if surplus measure occurs. In goods sawn using frame saws, however, it was difficult to discover any deviation from the correct measure.
The PDF includes a summary in English.
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Granvik,
E-mail:
bg@mm.unknown
