FRI BULLETIN No. 52

1. A peeling study method

for pruned logs

J.C. PARK

2. Grading veneers from

photographs

J. FIRTH and W.A.J. van DIJK

FOREST RESEARCH INSTITUTE

NEW ZEALAND FOREST SERVICE

FRI BULLETIN NO. 52

1. A PEELING STUDY METHOD FOR PRUNED LOGS

J.C. Park

2. GRADING VENEERS FROM PHOTOGRAPHS

J. Firth and W .A.J. van Dijk

FOREST RESEARCH INSTITUTE, NEW ZEALAND FOREST SERVICE

PRIVATE BAG, ROTORUA, NEW ZEALAND

1983

ISSN 0111-8129

ODC 826.1:854

CONTENTS

ABSTRACT

SECTION 1 - A PEELING STUDY METHOD FOR PRUNED LOGS (J .c. Park)

1.1 INTRODUCTION

1.1.1 1.1.2 1.1.3

Stand History and Assessment Log and Bolt Making and Marking Log and Bolt Measurements

1.2 PLANT SPECIFICATIONS

1.3 VENEER SPECIFICATIONS

1.3.1 1. 3. 2

Green veneer Dry Veneer

1.4 PEELING

1. 4.1 At the Lathe 1.4. 2 At the Trash Gate 1. 4.3 At the Clipper 1.4.4 At the Veneer Recovery Stations

1.5 VENEER MEASUREMENT, RECORDS, AND

1.5 .1 1.5.2 1.5. 3 1.5. 4

Green Veneer Measurement Green veneer Records Dry veneer Measurement Dry Veneer Grading

GRADING

1. 6 DEFECT CORE "RECONSTRUCTION" AND MEASUREMENT

1.6.1 Bolt Defect Core 1.6.2 Log Defect Core

1.7 DERIVATION OF RESULTS

1.7.1 Log and Bolt Data 1.7.2 Conversion 1.7.3 Program PEELER

1. 8 CONCLUSIONS

1. 9 REFERENCES

APPENDIX 1.1 - (A) PEELER LOG MEASUREMENT PROCEDURE

- (B) EXAMPLE OF A COMPLETED PEELER LOG MEASUREMENT FORM

Page

1

1

1

2 2 3

5

6

6 7

7

8 9 9 9

9

9 10 10 11

11

12 15

17

17 18 19

20

21

22

24

APPENDIX 1.2

APPENDIX 1.3

APPENDIX 1. 4

APPENDIX 1. 5

APPENDIX 1. 6

TABLE HEADINGS FOR SUMMARISING BASIC LOG AND BOLT PARAMETERS

EXAMPLES OF OUTPUT FROM PEELER LOG VOLUME PROGRAM

TABLE HEADINGS AND EXAMPLES OF SUMMARISED VENEER VARIABLES

PROGRAM PEELER

EXAMPLES OF OUTPUT FROM PROGRAM PEELER

SECTION 2 - GRADING VENEERS FROM PHOTOGRAPHS (J. Firth and W.A.J. van Dijk)

2.1 INTRODUCTION

2.2 METHOD

2.3 TECHNICAL DETAILS

2.3.1 Camera 2.3.2 Film 2.3.3 Camera Mount 2.3.4 Lens 2.3.5 Lighting 2.3.6 Veneer Support Table 2.3.7 Vibration 2.3.8 Scaling 2.3.9 Skirt 2.3.10 Projector 2.3.11 Costs

2.4 RESULTS

ACKNOWLEDGMENTS

25

26

27

28

34

37

37

37

39

39 39 39 39 39 40 40 41 42 42 42

42

44

ABSTRACT

The first section of this publication presents a method for detailed investigation of pruned peeler logs including a description of a computer program for data processing. The · method is designed to provide comprehensive results that allow veneer grade outturn and value to be related to measurable log parameters. A technique for "reconstructing", measuring, and determining the position of .defect cores is given. The method also provides for the evaluation of by-products from peeling and consequently can be used to determine gross log values.

The second section of this publication presents a detailed description of the photographic technique used to record veneer. Colour transparency photographs are taken of the veneers. Grading is then done using the projected images in the office. This new method is fast and efficient and provides a permanent record of each veneer sheet. Although this method was designed specifically for pruned logs, it has also been tested on unpruned logs and found to be highly suitable.

SECTION 1 - A PEELING STUDY METHOD FOR PRUNED LOGS

(J.C. Park)

1.1 INTRODUCTION

A primary objective of current silvicultural research at the Forest Research Institute is to evaluate results from pruning and from various silvicultural regimes under a range of utilisation options. The sort of questions to be answered concerning the peeling of pruned logs are:

*

*

*

What are the minimum requirements for a pruned. peeler log?

Which silvicultural regimes produce the best peelers?

How does peeling compare with other utilisation options on the same pruned log types?

* Which of the pruned logs in a crop would be best allocated to peeling?

Although standardised methods for conducting peeling trials have long been established (e.g., Knight 1956; Hailey & Hancock 1973), these were not designed to provide answers to the above questions. Therefore, it was necessary to design a new peeling study method.

The study method presented here provides a means of evaluating pruned peelers through detailed investigations of individual logs and their bolts. This approach has been followed in preference to any "batch" system because the major objective in forthcoming peeling studies is to relate veneer grades and values to pruned log parameters and thereby eventually provide for reliable predictions based on these variables. The disadvantage in studying logs and their produce in great

2

detail is that in order to be manageable, sample size must be restricted; however, this factor is of little consequence when the following advantage is considered: the results from each study completed by this method can be accumulated to provide a common data base that may be analysed in a variety of ways and that will continue to be useful and relevant in the future. Such a data base is essential to stand-modelling exercises, which include examination of peeling options, and to the development of computerised peeling simulation techniques.

Peelers cannot be evaluated by veneer grade outturn only: by-products from the peeling process also have a value and are included in deriving gross peeler log values per cubic metre of round log - $/m3 (r) • This value is directly equivalent to the gross sawlog values derived through the pruned log sawing study method (Park & Leman 1983) and means that value results, peeled versus sawn, from similar pruned log types can be directly compared. Costs of production are a separate issue and are not included in either the pruned peeler log study method or the pruned log sawing study method.

Two pilot studies on pruned peeler logs showed that a prerequisite for meaningful results was the isolation of processing variables and influences. There can be large differences between the potential conversions and grades of peelers and the conversions and grades that are realised in a particular plant on a given day. Therefore, a considerable amount of time must be spent in defining and monitoring the specific plant variables at the time of the study.

Although this study method was designed specifically to evaluate pruned logs, it has been used successfully for a large study of unpruned peelers (D .R. Page unpubl. data) . The only modification necessary for unpruned logs was substitution of data on knot size and condition for data on the pruned defect core. As neither of these variables is processed in the computer program, this method is also well suited to studies on unpruned logs.

1.1.1 STAND HISTORY AND ASSESS M ENT

In any study it is important to fully document the stand history and the condition of the stand at the time of sampling as well as the details concerning sample selection, including the portion of the stand that the samples represented. The stand history should be available from forest records. Unless trees selected are from permanent plots with current records, it is necessary to assess the stand. In addition to the usual summary of basic stand variables and distributions, this assessment should provide details of the distribution of defects in the pruned logs, including straightness categories, and any significant variation in pruning heights. Appropriate methods for stand assessments are given by Deadman and Goulding (1979).

1.1.2 LOG AND BOLT MAKING AND MARKING

There is a variety of ways in which pruned peeler bolts can be made from the pruned portion of stems and also a variety of possible bolt

3

lengths. However, for demonstration purposes, all examples given in this publication are assumed .to follow the most common practice in New Zealand - pruned butt logs crosscut at 5. 2 m for transporting and later cut to two 2.6-m peeler bolts. The butt half is designated as the "A" Bolt and the top half as the "B" Bolt. This study method can be used for any range of log and/or bolt lengths, and options have been kept open in the computer programs.

Prior to felling, the stems selected are allocated individual numbers. A vertical line is painted from the ground to approximately breast height on the side of the stem, which is at right angles to the most noticeable deviation in the butt logi it is easier to detect the more minor deviations from straightness when trees are standing rather than after the tree has been cut into logs. Diameter at breast height (d.b.h.) is measured and, in stands with variation in pruned heights, the length of stem that has been pruned is measured with a height pole.

After felling and bucking, log numbers punched on metal tags are nailed to the centres of log ends: these have been found to withstand rough treatment during extraction and debarking. The tag number on the butt end carries the suffix "A" and on the small end the suffix "B", for later bolt identification. The paint line is extended from the perimeter of the butt to the approximate centre of the butt end. An equivalent line is projected and painted on the small end.

After logs have been delivered to the plant, debarked, and cut into bolts, metal tags and nails are removed and bolt identification is either crayoned or painted on at least one end of each bolt.

1.1.3 LOG AND BOLT MEASUREMENTS

Log measurements may be carried out in the plant yard prior to debarking, but it is usually more convenient to complete them in the forest before the logs are extracted.

The objectives in log measurement are to record accurately the under bark profiles of parent logs and their bolts, to quantify any deviations from straightness, to get a measure of ovality, and to provide data for precise volume calculations. In the course of these measurements, sufficient data for calculating the volume of bar:.-, which may be classified as a saleable by-product, are also collected.

Diameter measurements are taken with calipers at 1. 3-m intervals, first in the plane of maximum log deviation from straightness, i.e., with caliper arms parallel to the paint line on log ends, and then in the plane at right angles to this. Two bark thickness measurements, one in each plane, are also taken at these points. Thus, profiles and volumes for logs are determined from five pairs of measurements large end diameter (l.e.d.) and small end diameter (s.e.d.) and one-quarter, one-half, and three-quarters log lengths - as well as for each bolt from three pairs of measurements- l.e.d., half bolt, and s.e.d.

Sweep and any other log deviations are measured from the central axis of the log and measurement points are the same as for the

4

intermediate diameters. The central axis is determined using a string line, nails, and two pairs of calipers that have been fitted with mobile centring pointers. The technique, which is demonstrated in Fig. l.l, is explained in detail in Appendix 1.1. Log deviations are measured in each plane at one-quarter, one-half, and three-quarters log length. The string line is then centred at half log length, i.e., the point that will become s.e.d. of the "A" Bolt and l.e.d. of the "B" Bolt; bolt deviations are measured at half log length on each bolt.

FIG. 1.1 - Technique for measuring log and bolt deviations

A. Determining the central axis of the log with calipers fitted with mobile centring pointers, nails, and string.

B. Measurements of log deviations: x, y, and z are measurement points at one-quarter, one-half, and three-quarters log length. The distance from top centre to the string line is measured in millimetres at each of these points.

c. Measurement of bolt deviations: the string line is hooked over the nail inserted at top centre half log; x1 and

zl are measurement points at half the "A" Bolt length and half the "B" Bolt length respectively.

5

Because precise log measurements are essential, procedures are listed step by step and accompanied by a completed example of a form for recording log data in Appendix 1.1.

After logs have been cut to bolts at the plant yard, further measurements are made. The geometric centre of each end of each bolt is located with the aid of a flexible clear plastic sheet marked with concentric circles. The radii of these circles begin at 10 cm and increase at 2. 5-cm intervals. The circles are colour-coded to ensure adjacent perimeters are easily distinguished from each other, and at the centre is a small hole. The sheet is placed against the bolt end and manoeuvred until the position of the circle of best fit against the bolt end perimeter is decided; then the geometric centre of the bolt end is marked through the. hole with an indelible pencil. The distance from the centre of the pith to the centre of the bolt end is measured in millimetres. If the intention is to peel bolts from their geometric centres, these should be centre-punched to ensure correct positioning in the lathe. If some other system for positioning bolts in the lathe is used, it is important to measure the distance from chuck centres to geometric centres. This procedure entails "touching in" and withdrawing lathe chucks to allow measurement immediately prior to peeling. Some measure of the ovality in bolts has been recorded at log measurement but, once both bolt ends are exposed, the absolute maximum and minimum diameter at each bolt end is defined. These diameters are found by pivoting a calibrated straight-edge through the geometric centres.

1.2 PLANT SPECIFICATIONS

It is unlikely that two different rotary veneer plants would ever produce identical results from identical logs. Because veneer production is very much affected by the specifications of the individual plant, it is essential that the basic plant specifications be recorded. It is also important for those involved in a study to be aware of what constitutes an abnormality in the areas they are monitoring. If any bolts within a sample are disadvantaged by temporary irregularities or malfunctions during peeling, clipping, or drying, losses and their causes should be identifieC. and, if possible, quantified.

Complete descriptions and detailed specifications of machinery are impractical. These fall into an area of high technology and are a separate subject. However, it is necessary to record sufficient detail on the plant to enable follow-up investigations if anomalous differences in results arise between plants. There are five production sectors that should be described and monitored and these are listed below together with guidelines on the minimum data to be recorded at the time of a study:

* Bolt preparation:

* Bolt positioning:

"Cooked" or peeled cold. If "cooked", then details of vats, heating method, temperatures, and cooking time should be recorded.

The system used to determine where lathe chucks are centred. If automated, then include the type, make, and model number of the lathe charger.

* Lathe:

* Clipper:

* Dryer:

6

The type, make, and model number. Include a brief description of backup rollers and nosebar.

The type, details of defecting

make, and model number. any sensory equipment for and details of manual

including instructions to operator.

Include automatic over-ride

The type, make, and model number. Also record settings used and total drying time for veneer from study logs. (If possible, the instruments on the dryer should be monitored constantly while study veneer is being processed.)

As much general information as possible should also be gathered from plant managers and other plant personnel regarding the idiosyncracies of their various machines and the settings that were used on the day of the testing. '

1.3 VENEER SPECIFICATIONS

The end-use or final panel size for which veneer is to be produced is the factor that dictates bolt length. For example, bolt length used to demonstrate techniques in this publication has been set at 2.6 m in order to produce most of the veneer as composite sheets for plywood panels sized 2400 mm x 1200 mm.

The allowances set for green and dry trimming, together with those made for shrinkage, influence conversion. If these are excessive, veneer is wasted; if they are inadequate, veneer is also wasted and values are lowered because many sheets that should have been full size end up too small. The specifications for retention of part sheets also have a direct effect on conversion, and standards vary from plant to plant.

It is not always necessary, and sometimes not advisable, to accept the criteria for allowances and veneer dimensions in current use at the plant where a study is to be carried out. If there are strong reasons, the study originator may alter these specifications for the period of the study. Veneer specifications, which must be adequately defined before a study commences, are listed below.

1.3.1 GREEN VENEER

*

*

*

Green sheet length: (mm)

Prescribed clipped width: (mm)

Prescribed green thickness: (to 0. 01 mm)

This is determined by the distance set between trimming scribes at the lathe.

For full size sheets.

For all veneer sheets.

*

*

Minimum strip width: (mm)

Fishtails: (mm x mm)

7

1.3.2 DRY VENEER

*

*

*

*

*

*

Prescribed moisture content (%)

Prescribed dry thickness (to 0.01 mm)

Acceptable dry thickness variation (2:_ to 0. 01 mm)

Panel size (mm x mm)

Dry trim allowance for strip and fishtails (%):

Reject sheets:

1.4 PEELING

Strip are full-length pieces that are less than full width.

Fishtails are produced at roundup; they are less than full length, and may be less than full width. The minimum acceptable width and length must be specified. (Some plants do not recover fishtails in their normal production runs, but they are impartant to pruned bolt values because they are usually completely clear pieces.)

These pieces may be used in plywood lay-up or for some other purpose. No matter what the end-use there will be a certain amount of waste that must be estimated and included as a reduction factor in calcula­ting conversions to dry utilised veneer.

Define the size of holes (mm) andjor the aggregation of knots and defects across the sheet (%) andjor the degree of splitting [length X width (mm) X number] that will render a sheet of veneer unusable.

Peeling is an operation that produces a high surface area and many pieces of product in a relatively short space of time. Because it is a "fast" process, a complete understanding between mill staff and study personnel must be reached before peeling commences to ensure that events on the green chain remain controlled. It is advisable to first peel one

8

or two "practice" bolts; these should identify areas of misunderstanding and indicate if changes in recording and numbering techniques are needed.

At the green chain the two major priorities are to isolate all areas of wood loss and to ensure that all pieces of veneer retained are adequately numbered. The most efficient means of achieving objectives will vary according to plant design. This study method was developed at H.T. Plywood Ltd., Mount Maunganui, and a schematic diagram of the green chain at that plant is given as an example in Fig. 1.2. Study procedures for each processing point are given below.

ASTE w CON VEYOR

r BOLT 1 LATHE

~ ~ ii TRASH GATE

VENEER

RIBBON

I CLIPPER

D D I

I I

L = = ~ ~

~ CONVEYOR

GRE RECOV

EN VENEER ERY STATIONS

a) FU LL SHEETS

b) s TRIP AND

ISHTAILS F

CLIPPI NG WASTE

FIG. 1.2 - Diagram of green chain at plant where study method was developed

1.4.1 AT THE LATHE

As a bolt is charged, its number is transmitted to personnel waiting down the chain by means of a blackboard mounted where all can see. As

9

the peel proceeds any irregularities are noted, e.g., sudden stops, breaking out at chucks, or loss of synchronization with the rest of the chain. When the peeled core is discharged, three diameter measurements are taken, one just inside the trimming scribe marks at each end and one at half length. Each end is also checked for differences between prescribed bolt centring and the point where the lathe chucks were centred; any discrepancies are measured in millimetres. The bolt number is written on the peeled core, which is stored.

1.4.2 AT THE TRASH GATE

An observer is stationed at the trash gate to ensure that all the scrappy pieces of· veneer that may meet the veneer specifications of the study are sent on down the green chain. Note is taken of any mistakes and estimates are made of the amount of any veneer that may have been sent erroneously to waste.

1.4.3 AT THE CLIPPER

Records of the number of pieces produced and the sequence of part and full sheets per bolt are made for later comparison with the final count of recovered veneer. Each part sheet produced is recorded as a dash and each full sheet as a vertical stroke. These sequences are accompanied, where necessary, by comments on clipping irregularities and reasons for breaks in the veneer ribbon from the lathe.

1.4.4 AT THE VENEER RECOVERY STATIONS

Veneers receive full identification and sequential numbering with coloured chalk at the recovery stations. Fishtails, strip, and full sheets are each identified by bolt and numbered in the sequence in which they were produced, e.g., if 42 pieces of veneer are produced from the "A" Bolt of Log 12, then numbering is 12Al, 12A2, 12A3 ••..•• 12A42. It is essential for later "reconstruction" of bolts that the suffix number of each piece of veneer correctly indicate its position il) the veneer ribbon.

1.5 VENEER MEASUREMENT, RECORDS, AND GRADING

1.5.1 GREEN VENEER MEASUREMENT

The green width of each full sheet and every piece of strip is measured in millimetres at half length. On each fishtail, the width is measured at the narrowest point that will remain after trimming the veneer to length.

Thickness measurements are taken on every sixth full sheet. A deep-throated micrometer with anvils loaded under a constant pressure is used to take three measurements inside the leading edge of the sheet.

10

Measurement points are marked with chalk to enable relocation after drying and are at half length and approximately 10 cm from each end. Because the accuracy of thickness measurements is critical, research into methods to improve the efficiency and precision is continuing; it is probable that a more specialized tool than that currently used would increase precision. Every sixth sheet is also measured for green length to get a precise measure of the effective distance between trimming scribes at the lathe, and to check against possible variation in the scribe settings.

1.5.2 GREEN VENEER RECORDS

All batches of veneer experience some degrade in drying. In a study situation every effort must be made to identify the amount of this degrade and to isolate, as far as possible, the causes. This is a complex subject and care should be taken in arriving at conclusions. The three factors that may contribute to· the deterioration of some pieces of veneer in the drying process are: characteristics of the bolt such as compression wood or marked eccentricity of the corewood, damage originating in the peel and/or on the green chain, and undue stresses caused by inappropriate drying schedules and/or dryer malfunction.

In order to differentiate between "drying defects" attributable to the intrinsic properties of the peeler bolt and those attributable to the plant it is necessary to obtain detailed descriptions of all veneer in the green state. These descriptions (green grading) are obtained by photographing each sheet and part sheet after placement on a frame over strong lights (as discussed by Firth and van Dijk in the second section of this publication). The resulting colour transparencies clearly show the difference between loose and sound knots, compression wood, cross-grain, splits, checking, and hairline cracks. Comparisons with the equivalent transparencies of the dry veneer help to isolate those defects already present in green veneer that are intensified by drying from those that originate in the dryer.

A second objective in photographing green veneer is to record details of the defect core to assist in the later "reconstruction" exercise. It is also very useful to have a visual record of the bolt's diameter growth to provide data on the more physiological aspects that may influence veneer grades, e.g., the formation of heartwood, compression wood, and randomly occurring defects such as resin pockets and adventitious shoots. Transparencies are kept in film strip form and stored as rolls; consequently, green veneer must be photographed in the correct sequence for each bolt. This should be a simple matter of following the numbering but checks should be made with the records taken earlier at the clipper to ensure that the numbering sequence is correct.

1.5.3 DRY VENEER MEASUREMENT

After drying, the width of every full sheet is remeasured. The lengths and thicknesses of those sheets that were marked and gauged in the green state are also remeasured and moisture content is measured with a meter for these sheets only.

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1.5.4 DRY VENEER GRADING

Complete dry veneer descriptions are recorded by photography in the method described by Firth and van Dij k later in this publication. Scale colour transparencies are taken of all veneer, and grading exercises are carried out by projecting the images onto a screen. This procedure allows a better view of the veneer than can be gained on site, improves the accuracy of grading, and facilitates any rechecking that may become necessary.

Randomly occurring defects that are not associated with the defect core, such as resin pockets and adventitious shoots, tend to confound results from pruned logs unless they are isolated. For this reason, veneers may need to be graded several times. For example, a sample that has both resin pockets and adventitious shoots is graded four times -ignoring random defects, including all defects, including resin pockets but not adventitious shoots, and including adventitious shoots but not resin pockets.

Differences in results are used to determine the effect each type of random defect has had on the sample being studied and to provide comm:m data for deriving predictions of their effect at various levels. This means that, when sufficient peeling studies have been completed, predictions from the common data base may be applied to any pruned stand and the effect of random defects will be accommodated by applying reduction factors for either the expected or sampled incidence of these.

Because veneer is permanently recorded on film the multiple grading required under one set of rules to produce comprehensive results does not present a problem. An added advantage is that veneer may be regraded at any time according to a different set of rules; this advantage becomes important when export options are being considered. It is an advantage, but not essential, to photograph dry veneer in the correct sequence.

1.6 DEFECT CORE "RECONSTRUCTION" AND MEASUREMENT

The need to determine the diameters of defect cores when pruned peelers are being studied is obvious, but pilot studies have identified that the position of the defect core within the stem is also critical. For saw logs,

"the defect core was defined as the "cylinder" containing pith, branch stubs, and occlusion scars. It included any widening effects due to stem sinuosity at the time of pruning. The size of this core was expressed by its diameter (in mm)." (Park 1980)

This definition applies equally to pruned peelers. However, a 5. 2-m pruned peeler log must be considered as having three defect cores - one for each bolt and one for the log as a whole. Most often· bolt defect cores are not fully contained in the peeled cores. Consequently, the "reconstruction" of defect cores is a multi-stage operation, which is time-consuming but not difficult provided that all the requirements of the study method have been met.

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1.6.1 BOLT DEFECT CORE

The numbered peeled cores, which were put aside earlier, are laid one at a time on a table. The remains of the paint line on one of the ends, which dictated the planes for log profile measurements, can still be detected and the peeled core is rolled until this line is vertical to ensure that diagrams of the defect core will be in the same two planes as the measured log profiles. The bolt number is written clearly on either side of the green core and then a photograph is taken of each side. The green cores are then taken to a band saw of known kerf, again positioned with the paint line vertical, and live-sawn. The thickness for these mini-flitches is not critical but should fall within the range 12 -24 mm. If flitches are thicker than 24 mm, too much guesswork is involved in defect plotting; if these are thinner than 12 mm, too much informa­tion is lost in saw kerf. Each flitch is identified by bolt number and also given a sequential number to assist in green core reconstruction.

Green cores are rebuilt and pith, branch stubs, and occlusion scars are plotted by lifting back flitches one at a time, first in the direc­tion of sawcuts and then in the direction at right angles. The informa­tion for each green core is recorded on two scale diagrams (Fig. 1.3).

2·5-

2·0-

1·5

1·0

0·5

0·0-

DIRECTION 1

T 1•7

1·3

o·a

0·7 0·6

CENTRAL AXIS OF BOLT GRID • 6mm

2·5-

2•1

2·0-

1•5

1•0

0·5 l 0'3

o·o I

1•7

1•3

DIRECTION 2

SCALE

HORIZONTAL • 1 : 2 VERTICAL • 1 : 20

FIG. 1.3 -Example of peeled core scale diagrams using results from "A" Bolt of Log 15 from Cpt. 1036, Kaingaroa

Forest

13

The peeled core illustrated in Fig. 1.3 was live-sawn to 24-mm flitches using a saw. with a kerf of 3 mm. The outside flitches were not 24 mm and were rounded on one side; their thickness was taken as the mean of the thickest points at the bottom and top end. A radial grid of 6 mm was used to assist in plotting. Direction 1 was the at right angles to the saw cuts and the first log profile measurements; thus each full flitch spanned three grids and each sawcut spanned half a grid. Radial plotting in Direction 2 where flitches lay flat, was achieved by measuring in from the outside edges of the widest flitch.

Heights to branches are measured from the bottom end of the green core and these measurements are written on the diagrams. The heights to branches and branch diameters shown on the diagrams do not need to be to scale. However, the path of the pith and the radial reach of defects must be plotted as accurately as possible, taking care to accommodate not only flitch thickness but also saw kerf as well.

METRES

o·o

PEELED CORE f -~-----~---~ ~ ---:-------:-(I)

25 B 53

0 .

.. • 0

------ -.o-------- ,_------ v-- 0 0

0 • 0

. INNER / - -=-- ---::--- -- -- -:..- -- -- -:_-VENE!;:RS~..-------------~-----~

0 0 c::>

25 B 52 . • a o

-------~--------;------.-- . . 0 . 0

. • =

-------o--------~------~-; 0

0

SCALE 1:20

FIG. 1.4 - Method of matching defects and tracing their radial extension

Occurrences of the same defects are traced back using reverse order of veneer sheet numbers until pruned stubs are identified and then until occlusion becomes complete.

14

The next step is to determine how far defects have extended beyond the peeled core. Branch stubs and occlusion scars not contained by the peeled core are identified as knots and scars appearing on the photographs of the outside of green cores. The configurations of knots and occlusion tissue occurring in the planes of interest on the peeled cores are matched with the same defects appearing on the inner sheets of veneer (Fig. 1.4).

The number of occurrences in the veneer of these same defects are counted out on the transparencies to the point at which the branches were pruned, and then to the point at which occlusion became complete. The distances from the outside of the green core to the end of defects are calculated by multiplying the number of occurrences (which show the number of revolutions of the lathe) by the actual green thickness of veneer as measured on each bolt (Appendix 1. 4) . By accumulating the information from the green core with that gained from the inner veneers, the total reach of the defect core in both planes may be calculated and the profiles plotted to scale as shown in Fig. 1.5.

2·5-

1·5-

1•0-

0·5-

o·o-

i c"m" ;"'

.,..__112mm-...

DISPLACEMENT (10mm)

!+---PEELED CORE DIAMETER--~ (177mm)

I I I I

t<t---- DEFECT CORE DIAMETER ------1 (234mm)

EFFECTIVE DEFECT CORE~ 234+ (2 x 10) ~254mm

SCALE HORIZONTAL= 1:2

VERTICAL ~ 1 : 20

FIG. 1.5- Example of a completed scale diagram of a bolt defect core in one direction

15

The example illustrated in Fig. l. 5 uses results from the "A" Bolt of Log 15 from Cpt. 1036, Kaingaroa Forest. The reach of defects beyond the green core was calculated by multiplying the number of times each recurred in the inner veneers by the actual green peel thickness, which for this bolt was 3.28 mm.

Often there is a significant difference between the central axis of the defect core and the central axis of the bolt. The effect is that more sheets of veneer are downgraded than the defect core size alone would indicate. Results are therefore incomplete and grade outturn cannot be fully explained until defect core displacement is included. The central axis of the bolt is also the central axis of the peeled core. It is defined on the scale diagrams by drawing a straight line between the points that are half-diameter at each end of the peeled core. The central axis of the defect core in each plane is defined by a line drawn parallel to the central axis of the green core. This line is placed at the point halfway between the most extreme reach of defects on either side. The distance from this line to the peeled core axis is measured on each diagram and converted to millimetres (Fig. l. 5). Defect core displace­ment for the bolt is derived from the plane in which the difference is greater and is a measure of the effective increase in the radius of the defect core. Therefore, the effective defect core diameter is the true defect core diameter plus twice the maximum displacement measured.

1.6.2 LOG DEFECT CORE

One of the research objectives of peeling studies is to provide comparative information for log allocation exercises. This method has been designed to output gross values per cubic metre of peeler log type and that are directly equivalent to gross saw log values from the sawing study method (Park & Leman 1983).

To compare results, peeled versus sawn, from specific pruned log types it is necessary to "reconstruct" the full peeler log length so that its parameters as a sawlog can also be defined. Full log profiles have been recorded at the time of log measurement and the data required to comple­ment these are complete defect core profiles for the lqg. At the completion of defect core plotting for the two bolts from a peeler log, the information on log defect core in two planes is contained in four diagrams. However, the defect core measurements from the "A" and "B" Bolts cannot be directly accumulated to give the correct defect core for the log. By definition, the reach of the defect core includes the enlarg­ing effect of sinuosity present in the stem at the time of pruning. Consequently, in most cases the log defect core exceeds the larger of the two bolt defect cores. Log defect cores in each plane are "reconstructed" to include sinuosity by the process shown in Fig. 1.6 and described below.

(l) The log profile is drawn to same scale as the bolt defect core (DC) profiles.

(2) The maximum cylinder available from each bolt is superimposed over bolt defect cores. The central axis of this cylinder is that of the peeled core, and its diameter is given as part of the computer output from Program PEELER (Appendix 1.6, Table 2). The diameter of

16

this maximum cylinder is a function of the shape of the bolt and the way lathe chucks were centred.

(3) The augmented defect core diagram of the "B" Bolt is mounted above that of the "A" Bolt. The path of the pith is matched at 2. 6 m, i.e., where the log was cut, and bolt diagrams are tilted until the positions of best fit in their respective halves of the log profile are determined.

(4) The log defect core in one plane is then plotted and measured to give DCl.

(5) All steps are repeated in the other plane to derive DC2. The defect core as a sawlog is the mean of DCl and DC2 (see definition in Park & Leman 198 3 • )

BOLT 128

Defect core = 221 mm

BOLT 12A

Defect core = 21 Omm

r-- ~ -

-

~ I I I I I I

V

I I

LATHE CENTRE

I ~PEELEo-1 I

L CORE _J MAXIMUM CYLINDER

LOG 12 Defect core = 230mm

FIG. 1.6 -Method of compiling and positioning log defect cores (example - Log 12 from Trial R347)

Method involves fitting bolt diagrams with maximum available cylinders superimposed inside diagram of log profile.

17

1.7 DERIVATION OF RESULTS

1.7.1 LOG AND BOLT DATA

Most log and bolt data are transcribed onto summary tables directly from earlier measurement records. Examples of how these should be summarised are given in Appendix l. 2 in the form of table headings. These table headings also serve as a summary of what must be measured and indicate the units of measurement to be used.

Log and bolt volumes are calculated by inputting the mean under bark diameters prepared on the log measurement forms [Appendix l.l (B)] to a log volume program.written by C.S. Leman. The volume formula, which was furnished by J.C. Ellis, calculates the butt 1.3-m section as a truncated cone (to accommodate any butt flare) and the volumes of all other sections as paraboloids using Smalian 's Formula. Typical output from this program is shown in Appendix 1.3.

Because the usefulness and application of the present expressions of taper and ovality in peeler logs remain largely untested, these have not been included in the computer programming. If these expressions were to be changed after future testing, it is most likely that any new formulae would still use measurements collected by the study method under discussion.

The provisional taper index for peeler logs is defined, as for sawlogs, as the rate of taper between the diameter l. 3 m from the butt and the small end diameter. This prevents the calculated rate of taper becoming unrealistically inflated by any butt flare that may occur.

Taper Index (mm/m) = D - d L - 1.3

where D diameter (mm) at 1.3 m

d s.e.d. (mm)

L log length (m)

At present the general ovality of the log is expressed as a ratio calculated by dividing the mean of all over bark (o .b.) diameters in one plane by the mean of those taken in the other (i.e., means of the first two lines of records in Appendix l.l(B); the larger mean is divided by the smaller) • Expressions of ovali ty in bolts are more speci fie. The ratio of ovality at each end of each bolt is calculated from the maximum and minimum diameters inside bark (d.i.b.) determined and measured after bolts were cut from logs. Although the ovality at the small e.nd of bolts has the greater effect on conversion, it is necessary to define any ovality present at the large end because this may have an effect on the production of fish tails and strip since fish tails and strip from pruned logs are usually clear veneer.

18

1.7.2 CONVERSION

Because a major objective in this study method is to derive accurate gross bolt and log values, it is essential that total round volume be accounted for and that the various by-products and residues be given appropriate values. The volumes of veneer, the peeled core, scribing residues, round-up and clipping residues, dry trim residues (from plywood lay-up), any reject veneer, and volume reduction resulting from shrinkage must each be isolated and their accumulated volume must equal that of the peeler bolt. To achieve this goal it is necessary to recognise three types of conversion. The first two of these relate to green veneer because, in order to arrive at the required thickness of dry veneer, a target (nominated) thickness, which makes allowance for the shrinkage expected on drying, is set at the lathe. However, the actual green thickness of veneer produced often differs from that nominated and also tends to vary slightly among bolts. Because such a large surface area of product is involved, these small variations cause significant differences in calculated volumes.

* "Actual" Green Conversion: Derived from the true volume of the green veneer, which is calculated by multiplying the green surface area of all veneer from a bolt by the mean of the measured veneer thicknesses for that bolt.

* "Nominal" Green Conversion: Derived from the effective volume of green veneer, which is calculated by multiplying the green surface area of all veneer from a bolt by the nominated green peel thick­ness, i.e., the green volume expected from the surface area produced.

In the course of calculating veneer volumes for each of these two green conversions the volumes of peeled cores, scribing residues, and roundup and clipping residues are determined as well.

Veneer is priced by the utilised surface area (at the prescribed thickness) in the dry state, and further residues from rejects and dry trim after lay-up, together with volume reduction resulting from shrinkage, are isolated when the dry utilisable volume of veneer is calculated. The final surface area of full sheets is determined by the plywood panel size, and dry trim residues are calculated from the difference between the size of dried veneer sheets and panel size. Determining the amount of dry trim for strip and fishtails is not as straightforward because they may be used as cross-banding in plywood lay-up or, when of the high grade expected from pruned logs, aggregated for faces. High-grade strip and fishtails may also be regarded as valuable by-products and have uses other than in plywood such as in laminated furniture components, pressed trays, and ice cream sticks. To keep strip and fishtails on an equivalent basis to full sheets, their end use must be defined and the amount of waste from dry veneer to the finished product estimated as a reduction factor to be applied to all pieces. If insufficient information is available, a default value of 12% is suggested; this value approximates the reduction expected from full sheets.

*

19

Conversion to Dry Utilised veneer: Derived from the effective volume of veneer that will be incorporated in the final product. This volume is calculated by multiplying the utilisable surface area of full and part sheets by the prescribed thickness for dry veneer.

NOTE: Dry volume is defined as effective rather than actual because of tolerances allowed for variation in the thickness of dry veneer. When veneer exceeds these tolerances, sheets are classed as rejects.

Each of the three conversion types is expressed round bolt volume and is computed by Program PEELER. aggregates bolts to give conversion results for logs.

as percentages of This program also

The volumes of the various residues and by-products, and the percentage of bolt volume each represents, are also output by the program.

Procedures described earlier will furnish all the required input to Program PEELER with the exception of two veneer and plant-related vari­ables that must first be calculated from data collected. These are actual green peel thickness and shrinkage. Actual green peel thickness is the mean of all green thickness measurements taken per bolt and is calculated to 0.01 mm. Tangential, radial, and longitudinal shrinkages are each expressed as reduction factors and are calculated by dividing the totals of dry measurements per bolt for width, thickness, and length respec­tively by the corresponding totals for green measurements. Shrinkage reduction factors are calculated to three decimal places. Apart from being essential input to Program PEELER, each of these variables may con­tribute to explaining results and therefore are summarized as shown by the table headings and examples given in Appendix 1.4. Moisture content after drying is not part of the computer input, but it is also included in the table because both the degree to which veneer is dried and the variations in drying are directly related to shrinkage and may significantly influence veneer grades. Dry moisture content is the mean to one decimal place of all the dry sheet moisture percentage readings taken per bolt.

1.7.3 PROGRAM PEELER

Conversions, grade outturn, and values are derived using Program PEELER. This program was written in extended BASIC for a PDP 11/34 computer by J.W. Parsons. The program has been designed to calculate the utilisable surface area and volume outturn in each grade as full sheets, and as strip and fishtails. The volumes of each of the remaining by-products and residues are also calculated. This total segregation of the produce allows any chosen price to be allocated to each element. The program outputs a detailed breakdown of veneer grades and residues, identifies the value contributions made by each, and accumulates these to give gross bolt and log values. Details of input procedures are given in Appendix 1.5.

OUtput from Program PEELER details results from individual bolts and accumulates these to give results for parent logs. The program will

20

process up to three grading routines on the same produce simultaneously and results are presented in the form of equivalent tables. When all the options are exercised, Program PEELER generates 30 tables of output for each log sample. For demonstration purposes, five basic tables are given in Appendix 1.6 and are explained in the text below. Note that in the examples shown veneer has been allocated grades according to the New Zealand Construction Plywood Standard (NZS 3614).

In Table 1 of Appendix 1.6 bolt and log volumes are shown as are the volumes from the various types of green and dry residues. Volumes for the three types of conversion are given, variation in peel thickness is identified by individual bolts, and volume losses resulting from shrinkage and absolute rejects are also isolated. Mean clipping width and clipper variation for each bolt are also given in Table 1. In Table 2 of Appendix 1.6, bolt size is expressed by s.e.d., log size by d.b.h., and the volumes of conversions, residues, and losses from Table 1 are converted to percentages of round bolt and log volume. To assist with defect core "reconstruction" as described earlier, the diameter of the maximum cylinder available from each bolt is also given in Table 2.

All other tables output from Program PEELER are based on conversion to dry utilised veneer only. Because it is necessary to know the contribution to total veneer of strip and fishtails and because it may be desired to price these at a lower level than full sheets, they are isolated. For each of Tables 3, 4, and 5, which are given as examples in Appendix 1.6 and which show total veneer out turn and value, an actual computer run generates two further tables in the same format. The first shows the contribution made by full sheets and the second shows the contribution made by strip and fishtails. Table 3 gives the breakdown of the utilised volume of veneer by grades for each bolt and log. In the right-hand section of this table these volumes are expressed as percentages of round bolt and round log. In Table 4 the veneer from each bolt is expressed as the area (m 2 ) produced in each grade. Table 5 displays the price/grade matrix ($/m2 of veneer) for full sheets and for strip and fish tails (in the example given the prices remain the same). The distribution of grades by sur face area from Table 4 is converted into a dollar value for veneer, first by the contribution from each grade, and then with dollar values accumulated to give totals for veneer value per bolt and per log. In the right-hand section of Table 5 the value of green cores and other residues (loosely termed as waste) are also shown. The total value of all produce from each bolt and each log is accumulated and then further converted into gross value per cubic metre of round bolt and round log [$/m3(r)]. The log values [$/m3(r)] shown on this table are directly comparable to gross sawlog values derived using the sawing study method developed by Park and Leman (1983).

1.8 CONCLUSIONS

This section of the publication has defined methods of measurement and data collection for peeling studies and explained the principles and logic applied. The subsequent portion of this publication prepared by Firth and van Dijk provides a method for gaining high quality colour transparencies of veneer to facilitate grading, defect core "reconstruc-

21

tion", and investigations into the intrinsic properties of peeler bolts. These two papers together constitute a complete and standardised method of evaluating pruned peeler logs.

The importance of monitoring the plant while a study is in progress has been stressed. Peeling results are very sensitive to plant variables and results are incomplete unless accompanied by a description of the plant and the practices employed. This is essential to assist in value judgements if results from different plants are to be compared or accumu~ lated. The records, in combination with computer output, should also identify any individual bolts within a sample that may have been disadvan­taged because of an accident, a departure from normal practice, or a mal­function of the plant. The purpose in identifying disadvantaged bolts is not to allow for adjustment, but rather to provide explanations for some of the variation in results and, when the disadvantage resulting from plant variables is judged as serious, a reason for exclusion from sample results and/or the common data base. Unless there is a valid reason for exclusion, any strange results must be included in the common data base. These results will cause an undesirable increase in variation from accumulated results and hence a lowering in the precision of any predictions.

1.9 REFERENCES

DEADMAN, M.W.; GOULDING, C.J. 1979: recoverable volume by log types. Science 9(2): 225-239

A method for the assessment of New Zealand Journal of Forestry

HAILEY, J.R.T.; HANCOCK, w.v. 1973: Methods and techniques for veneer peeling research. Information Report VP-X-107. western Forest Products Laboratory, Vancouver, British Columbia, Canada.

KNIGHT, R.A.G. 1956: Manual for Conducting Trials of Timbers for Plywood Manufacture. Department of Scientific and Industrial Research, Forest Products Research Laboratory, Princes Risborough Laboratory, Britain.

STANDARDS ASSOCIATION OF NEW ZEALAND 1971: Specification for Manufacture of Construction Plywood. NZS 3614:1971 18 p.

PARK, J.C. 1980: A Grade Index for pruned butt logs. New Zealand Journal of Forestry Science 10(2): 419-38.

PARK, J.C.; LEMAN, C.S.E. 1983: A sawing study method for evaluating timber from pruned logs. New Zealand Forest Service, FRI Bulletin No. 47.

22

APPENDIX 1.1

(A) PEELER LOG MEASUREMENT PROCEDURE

Instructions for log measurements are listed here and an example of a completed log measurement form is given as Appendix l.l(B).

(1) Enter the log number.

(2) Turn the log until the painted line on the end is vertical - this means that the first measurements will be taken in the plane of maximum sweep.

(3) Run a tape down the log and mark the intermediate measurement points with paint spots (i.e., 1.3 m, 2.6 m, 3.9 m).

(4) Using calipers with the calibrated bar in the horizontal plane, measure diameters at the large end, the intermediate points, and the small end- these are diameters A [Appendix l.l(B) ].

(5) Using a Swedish-type bark gauge, take two bark thicknesses at each measurement point. The first is taken on the side (Plane A) and the second on the top of the log (Plane B).

(6) Using two sets of calipers with centring pointers, determine top centre at the large end and at the small end. Ensure the two cal ipers line up with each other so that there is no skewing in plane. Leave calipers at small end in position for reference until all sweep measurements in this plane are completed.

(7) Insert a nail perpendicularly at top centre at the butt end and stretch a string from this nail to the centre pointer on the calipers at the small end.

(8) With calipers and pointer determine top centre at half log length (i.e., 2.6 m). Measure (in mm) from the string line to the centre of the pointer (see Fig. 1.1 in text). This is maximum deviation at mid-log length. The recorder sights along the string line from the butt end; when the string is on the left side of the pointer deviation, measurements are recorded as "-" and when on the right side of the pointer they are recorded as "+".

(9) Mark top centre at half log by indenting the bark with the pointer on the calipers. Remove calipers and insert a nail perpendicularly at the mark.

(10) Repeat the procedure in Step 8 at one-quarter log length (1.3 m) and three-quarters log length (3. 9 m). This completes ~ deviation measurements in Plane A.

(11) To measure deviation in bolts the taut string line is hooked over the nail at half log length (Fig. 1.1). The measurement points that were one-quarter and three-quarters log length have thus become half Bolt "A" and half Bolt "B" respectively. Calipers are repositioned at these points, top dead centre relocated, and the distance from

23

the new position of the string line measured. Bolt deviation records are entered next to log deviations as shown in Appendix l.lB.

(12) Remove calipers, string and nails and turn the log through 90°, i.e., until the paint line on the log end is horizontal. Repeat Steps 4 to 11 with the exception of Step 5, sufficient bark measurements have already been taken.

If the bark should be displaced from one side of a log at a point at which measurements are to be made with calipers, the bark must be removed from the opposite side to prevent incorrect readings. In such a case, bark thickness is entered as "0" for that measurement point in that plane.

The recorded .data on diameters and bark thicknesses are used to calculate manually diameters inside bark (d. i.b.) as shown in Appendix l.lB. These calculated d. i. b. are the input required by program Ll3VOL that computes underbark log and bolt volumes.

24

APPENDIX 1.1

(B) EXAMPLE OF A COMPLETED PEELER LOG MEASUREMENT FORM

1-"3· t-1 ~

11 ~ t

' _o_~. ~, l~A ;7._4<, i i.)~. 'i IJIA~t.. D $ ~A. IJ!Al<JC...

f+t;o ;:l.J 4_:3 ':_ , .. _, t . 3 l '9 £+ {') I '- - - - - -·

u.so :J-4- U,/..5 Jl} 4-:2.0 1. ~o -- ·----·----1------- +---

<Joo '+5 1 'b&i $1 ))So!, 31 - ..... -=-- -tT:,----j--, . '

45<> / /::~ t+JO% 4-A$1~ :t'//f01V' ij~ L .L7 'I J lfo5 / '1':1 "l'iJ 1 ~~~_t ___ /J.

25

APPENDIX 1.2

TABLE HEADINGS FOR SUMMARISING BASIC LOG AND BOLT PARAMETERS

TABLE 1 - Peeler log summary

Log d.b.h. s.e.d. Volume Deviation Taper Ovalness Defect no. ( o. b.) (i.b.) (m3) at mid-log index ratio core

(mm) (mm) ------------ (mm/m) diameter max. mean (mm) (mm) (mm)

12 500 386 0. 712 16 15 11 1.01 230

TABLE 2 - Peeler bolt summary

Peeler bolt

Small end Diameter (mm) Ovality ratio Pith eccentricity (mm)

Large end Diameter (mm) Ovality ratio Pith eccentricity (mm)

Deviation at mid-bolt (mm)

Defect core Diameter (mm) Displacement (mm)

l2A

405 1.04

10

495 1.02

17

0.395

11

226 16

12B

386 1.06

16

405 1.04

10

0.317

19

264 6

26

APPENDIX 1.3

EXAMPLES OF OUTPUT FROM PEELER LOG VOLUME PROGRAM

Peeler Log No. 8 - No. 12 from Trial R347

Log No. 8

0.0-1.3 1.3-2.6 2.6-3.9 3.9-5.2 0.1702 0.1321 0.1077 0.0941

Bolt "A" volume 0. 0-2. 6m 0.3023 Bolt "B" volume 2.6-5.2m 0.2018 Total log volume 0. 5041

Log No. 9

0.0-1.3 1.3-2.6 2.6-3.9 3.9-5.2 0.1720 0.137 3 0.1233 0.1136

Bolt "A" volume 0.0-2.6m 0.3093 Bolt "B" volume 2.6-5.2m = 0.2370 Total log volume 0. 5462

Log No. 10

0.0-1.3 1.3-2.6 2.6-3.9 3.9-5.2 0.1966 0.1580 0.1455 0.13 98

Bolt "A" volume 0.0-2.6m 0. 354 6 Bolt "B" volume 2.6-5.2m = 0. 2853 Total log volume 0. 6399

Log No. ll

0.0-1.3 1. 3-2.6 2.6-3.9 3.9-5.2 0. 2138 0.1800 0.1594 0.1464

Bolt "A" volume 0.0-2.6m 0.3938 Bolt "B" volume 2.6-5.2m = 0.3057 Total log volume 0.6996

Log No. 12

0.0-1.3 1.3-2.6 2.6-3.9 3.9-5.2 0.2174 0.1768 0.1626 0.1549

Bolt "A" volume 0.0-2.6m 0.3942 Bolt "B" volume 2.6-5.2m 0.3175 Total log volume = 0. 7117

27

APPENDIX 1.4

TABLE HEADINGS AND EXAMPLES OF SUMMARISED VENEER VARIABLES

Bolt no.

12A

12B

TABLE 1 -Veneer green thickness, shrinkage, and dry sheet moisture content

Green peel Shrinkage reduction factors Dry thickness ----------------------------------

(mm) tangential radial longitudinal

1. 64 . 0.908 0.950 0. 989

1.67 0.926 0. 9 50 0.992

veneer m. c. ( %)

6.0

5.7

28

APPENDIX 1.5

PROGRAM PEELER (1

)

Program PEELER is a computer program to calculate volumes, areas, and values in the conversion of green logs to dry utilisable veneer. Program PEELER is written in extended BASIC for a POP ll/34 computer, and will process up to three grading routines on the same produce, for a maximum of 42 bolts. The program is interactive, requiring responses from the user at various intervals.

Input:

* *

*

There are three categories of data input:

General data relative to the whole study

Data relative to each log

Data relative to each bolt

Note: Commas are used to separate data entries on one line.

General Data

(a) Number of grades used (integer value in the range 1 to 6)

(b) Grades used, e.g., AN, A, B, etc., listed one per line

(c) Number of grading routines used (integer value in the range l to 3)

(d) Title for each grading routine, one per line, e.g., NOT ADJUSTED

(e) Bolt length (mm), scribe width (mm), dry veneer thickness (mm),

nominal peel thickness (mm)

(f) Dry sheet dimensions (mm), i.e., length, width

(g) Reduction factor for strip, e.g., for 12% input 0.88

Log Data

(h) Log no., log d.b.h. (cm), log length (m), log s.e.d. (mm), log vol

(m3

x 10 - 2 )

(l) Written by J. w. Parsons

29

Bolt Data

(i) Bolt identification (log number + A or B) e.g. 13A

(j) Bolt volume (m3

x 10-2), s.e.d. (mm), l.e.d. (mm) , veneer

thickness (mm) , deviation from central axis (mm) , followed by three

shrinkage factors

decimal places)

tangential, radial, longitudinal (to three

(k) Green core diameter (mm)

(1) Number of full sheets

(m) Sheet no., green width (mm), Grade 1, Grade 2, Grade 3

11 11 11 11 11 11 , etc.

(n) Letter A (Absolute rejects) , number of rejects

(o) Sheet number, width (mm)

(p) Letter F (Fishtails) , number of fishtails

(q) Fishtail sheet number, width (mm), Grade 1, Grade 2' Grade

11 11 11 11 11 11 11 11

( r) Letter R (Rejects to strip) , number of rejects

(s) Reject sheet number, width (mm) ' Grade 1, Grade 2, Grade 3

11 11 11 11 11 11 11 11

(t) Letter s (Strip) , number of strips

( u) Strip sheet number, width (mm) ' Grade 1, Grade 2' Grade 3

11 11 11 11 11 11 " 11

(v) Letter Y(yes, another bolt from this log- repeat from (i))

or N(no, end of data for this log- repeat from (h))

or E(end, end of data for this study)

Output:

3

etc.)

etc.)

etc.

omit

if

no

data

The program generates a series of summary output tables, some of which are

optional. Tables 1 and 2 are generated automatically.

To Run Program PEELER

Type RUN Dev:[ppn]PEELER

(Note - Dev: is the name of device on which the program is stored;

[ppn] is the project programmer number of account where

PEELER is stored - specific to installation.)

30

The program title is screened, followed by a message asking for a filename to be input. This should be of the form "filnam. ext" where "filnam" is an identifying name of up to six characters. The "ext", extension, would normally be .DAT for a data file or .LST for an output file. After the data f ilename has been input, the program requests a name for the output file in the form "filnam. ext" where the extension would normally be ".LST".

Apart from the first two summary output tables which are automatically set up, the other output tables are optional. The program requests that you type Y(es) or N(o) as each output option is screened. There are three options available, namely, volume, area, and value of veneer by grade. Within each option ·three tables are produced for each grading routine specified - full sheets; strip and fishtails, and total veneer.

The price list <Sim2 ) is entered via the screen, with one price per grade per line. The program causes each grade to be screened as a prompt for the corresponding price. There is an option to input a separate price list for strip and fishtails. Prices are requested for green residues, dry residues, and green cores.

PEELER reads the data from the specified input file for each bolt, processes it, and outputs the results for that bolt to the specified output file. The message "END. OF BOLT ••• " is then screened before the next bolt data is read. After all the data has been processed, the various sunnnary output tables are set up with a message screened as each table is completed.

At the completion of the run the program asks if there is another price list, in which case the prices are input from the keyboard as before and further tables are set up using the new price list.

Example of Data Input File - PEEL .DAT Data for one log only

6 AN

A B

CP c D

2 NOT ADJUSTED EXCL R.P. 2600,2500,3.176,3,334 240011200 0.88 13,50.5,5.2,408,78.2 13A 42.3,433,514,3.1,9,.923,.943,.999,179 21 20,1256 ,AN ,AN 2l,l412,AN,AN 22,1412 ,AN ,AN 23,1397,AN,AN

31

24,1406,AN,AN 25,1395,AN,AN 26,1390,CP,AN 27,1369,AN,AN 28,1380,AN,AN 31,1370,AN,AN 32,1387 ,AN,AN 33,1392,AN,AN 34,1403,AN,AN 35,1394,AN,AN 3 6, 13 98 , AN, AN 37,1390,AN,AN 38,1389,AN,AN 39,1396,AN,AN 40,1280,AN,AN 41,1395,A,AN 43,1404,B,B F,11 3,300,B,B 4,310,B,B 5,280,B,B 6,360,B,B 7,300,B,B 8,320,CP,B 9,250,B,B 10,330,B,B 11,260,B,B 11,450,B,B 15,230,B,B 8,11 11,240,AN,AN 12,330,AN,AN 13,340,AN,AN 14,840,AN,AN 16,980,AN,AN 17,1030,AN,AN 19,1130,AN,AN 26,460,CP,AN 27,330 ,AN ,AN 44,390,AN,AN 45,360,B,B y

13B 35.9,408,433,3.3,25,.936,.937,.997,176 17 16,1330,D,D 17,135l,C,C l8,1360,AN,AN l9,1370,AN,AN 20,1358,AN,AN 21,1371,AN,AN 22,1366,A,A 23,1383,A,A 24,1368 ,A,A 25,1413,CP,CP

26,1408,CP,CP 27,1412 ,CP ,CP 28,1402,CP,CP 29,1418,C,C 30,1393,C,C 31,1416,C ,C 32,1312,C,C F ,3 5,620,B,B 6,560,B,B 7,530,B,B S,8 8 I 370 ,AN ,AN l0,610,AN,AN ll, 560 ,AN ,AN l4,700,AN,AN l5,928,AN,AN l5,1000,AN,AN l6,1030,AN,AN l7,580,AN,AN E

32

Example of a Typical Run of Program PEELER

RUN [lO,l5]PEELER

R.P.T.F. PEELER STUDY PROGRAM- J.W. PARSONS 24/9/82

All prices are input from the keyboard including the option of a different price list for strip & fishtails

Input name of data file ? PEEL.DAT Input a name for your output file ? DLl:PEEL.LST

Output table options required - type Y(es) or N(o) Volume of veneer by grade ? Y Area of veneer by grade ? Y Value of veneer by grade ? Y

Price list ($/m2) - input one price per grade per line AN? 2. 00 A? l. 86 B? l. 62 CP? 1.36 C? 1.10 D? 0.94

Is there a different price list for strip & fishtails (Y/N)? N

Prices for residues [$m3(r)] and cores - input as prompted Green residues? 12.50 Dry residues ? 12.50 Green cores ? 34.47

END OF BOLT 13A END OF BOLT 13B END OF BOLT 14A END OF BOLT 14B END OF BOLT 15A END OF BOLT 15B END OF BOLT 16A END OF BOLT 16B END OF BOLT 17A END OF BOLT 1 7B END OF BOLT 18A END OF BOLT 18B TABLE 3 FINISHED TABLE 4 FINISHED. TABLE 5 FINISHED TABLE 6 FINISHED TABLE 7 FINISHED TABLE 8 FINISHED TABLE 9 FINISHED TABLE 10 FINISHED TABLE 11 FINISHED TABLE 12 FINISHED TABLE 13 FINISHED TABLE 14 FINISHED TABLE 15 FINISHED TABLE 16 FINISHED TABLE 17 FINISHED TABLE 18 FINISHED TABLE 19 FINISHED TABLE 20 FINISHED

33

Is there another price list (Y or N) ? N

TO LIST OUTPUT ON SCREEN TYPE PIP DL1:PEEL.LST FOR HARD COPY TYPE QU DLl:PEEL.LST

Ready

34

APPENDIX 1 .6

EXAMPLES OF OUTPUT FROM PROGRAM PEELER

CONTENTS

TABLE l - Conversions and residues by volume.

TABLE 2 - Conversions and residues as percentage of round bolt and round log.

TABLE 3 - Distribution of veneer grades by volume and by percentage of round bolt and round log.

TABLE 4 - Distribution of veneer grades by area produced.

TABLE 5 - Value of veneer and residues, and gross bolt and log values.

NOTE: Examples show results from one grading routine only; two other grading routines may be run simultaneously, if required, and produce equivalent tables. For example, Tables 3, 4, and 5 show Total Veneer only. An actual computer run produces two further sets of tables (for each grading routine); the first set shows the contribution from full sheets of veneer and the second shows the contribution from strip and fishtails.

35

04-M.ay-83 at 14111 PEELER - PARK/PARSONS TABLE 1 CONVERSION OF GREEN LOGS TO DRY UTILISABLE VENEER

VOLUMES - (m3 x 10-~)

Cl

LOG BOLT LOG BOLT VOL VOL

13

15

16

17

18

A B

A B

A B

A B

42.30 35.90

78.20

46. 10 36. 91)

83.00

46.70 41.00

87.70

53.30 44.60

97.90

A 63.10 B 51. 20

114.31)

R E RES I DUES

GREEN ROUNDUP CORE CLIPPER SCRIBE

6.54 6. 33

12.87

6,40 6. 54

12.94

6.47 G.47

12.94

6. 47 6,47

12.94

G. 40 6. 69

13.09

3.59 3.63 7.21

5.88 2.43 8. 31

3. 72 0.85 4.57

2.21 1.06 3.27

9,10 2.79

11.89

1. 52 1.15 2.67

1. 63 f. 17 2.80

I. 57 1. 30 2.86

I. 87 1.52 3.39

2.28 1. 71 3.98

E N

GREEN VENEER ACTUAL NOMINAL

::so. 65 24. eo 55.4:5

32.20 2G. 75 58.95

34.95 32.38 67.33

42.75 35.55 78.30

45.32 40.02 85.34

30.96 25.06 56.02

31.85 27.61 59.47

35.52 32.92 68.44

43.59 36.02 79.61

44.97 41.05 86.02

D R y DRY THICKNESS DRY

UTILISABLE VENEER

CLIPPER WIDTH VARIATION SrlRINKAGE TRIM ABSOLUTE LOSS/

LOSS WASTE REJECTS GAIN

4.00 3.12 7.11

4.22 2.18 6.40

4,19 3.07 7.26

5.56 3.78 9.34

6.45 4.10

10.55

2.68 2. 20 4.88

2.12 3.21 5.33

2. 98 3.78 6.77

2.87 3.18 G.05

2.58 3.89 6.47

o.oo 0.00 o.oo

o.oo 0.00 0.00

0.00 0.00 o.oo

o.oo 0.00 o.oo

0.00 o.oo 0.00

-0.27 -0.22 -0.50

0.30 -o. 79 -0.49

-0.51 -0.48 -0.99

-0.73 -0.42 -1. 1:S

0.30 -0.93 -0.63

24.24 19.71 43.95

25.56 22.15 47.71

28.27 26.02 54.29

35.05 29.01 64.06

35.99 32.95 68.95

TOTAL SAMPLE

MEAN S. D.

1382.10 1378.29 1380.39

1361.00 1359.91 1360. 50

1370.00 1382.46 137G. 00

1347.35 1347.43 1347.39

39.73 31.25 35.77

18.65 18.73 18.49

4&.93 14.03 35.42

26.17 15.58 21.86

1350. 48 24. 46 13:54. 78 25. 97 1352.60 25. 11

1364.43 31.73

04-M.ay-83 .at 141 11 PEELER - PARK/PARSONS TABLE 2 CONVERSION Oi~ GREEN LOGS TO DRY U":"ILISABLE VENEER

PERCENTAGES OF ROUND VOLUME

G

t_QG BOLT LOG BOLT OBH SED

(ctro) (Cil'l)

13 A 43.30 B 40.80

50.50

15 A 42. 90 B 42.30

52.40

16 R 45. 40 B 43.30

54. 10

17 A 49.40 B 45.40

e.o. 20

18 A 51.00 B 49.00

50.30

PEE<..ER - PARK/PARSONS

R E RES I DUES

GREEN ROUNDUP CORE CLIPPER: SCRIBE

15.47 17.62 16.46

13. BB 17.73 15.59

13.85 15. 7.8 14.75

12.14 14.51 13.22

10. 14 13.07 1!. 45

8. 48 10.10 9.2:2

12.74 6.59

10.01

7.95 2.07 5.21

4.14 2.38 3.34

14.43 5.41'

10.40

3.60 3.19 3. 41

3.54 3.18 3.38

3.35 3.16 3.26

3.51 3.41 3.46

3.61 3. 33 3.48

E N

GREEN VENEER ACTUAL NOMINAL

72.45 73.20 69.09 G9. 80 70.91 71. 64

€.'3.84 69.10 72.50 74.83 71.02 71.65

74.83 76.06 78.99 80.29 76.77 78.04

80.21 79.71 79. ss

81.78 80.77 81.3.2

71.83 71.27 78. 16 eo. 18 74.66 75.26

TABLE 3 CONVERSION OF GREEN LOGS TO DRY UTILISABLE VENEER

LOG BOLT

13 A B

TOTAL

15 A B

TOTAL

16 A B

TOTAL

17 A 9

TOTAL

18 A B

TOTAL

AN

19.94 7. 2'3

27.22

11.50 7.G3

19.13

6. 34 0.91 7.25

1.34 3. "30 5. 24

5.62 12.88 18.50

VOLUME <m3 K 10-2> OF VENEER BY GRADE NOT ADJUSTED - TOTAL

A

o. 91 z. 74 3.GG

0.00 (1.91 o. 91

1. 05 0.00 1. 05

0.00 0.00 0.00

1. 83 1.83 3.66

B

2.09 o. 54 2.62

2.69 2.34 5.02

7.84 2. 02 9.87

e. 23 5. 39

13.62

2.63 1.11 3. 75

CP

1. 30 3.G6 4.96

3.66 2.12 s. 78

6.40 7.54

13.94

14. 10 10.11 24.20

20.20 5.49

25.69

c

0.00 4.57 4.57

3.66 2. 74 6.40

6".64 13.26 19.90

10.47 5.95

16.42

3.88 10.73 14.61

D

o.oo o. 91 o. 91

4.05 G. 40

10.46

0.00 2.28 2.28

0.91 3.66 4.57

1. 83 0.91 2:.74

TOTAL

24.24 19.71 43.95

2:i. 56 22. 15 47.71

28.27 26.02 54.29

35.05 2:9.01 64.06

35.99 32.95 68.95

D DRY THICt(NESS

SHRINt\AGE TRIM AEISDLUTE LOSS/ LOSS WASTE REJECTS GAIN

9.45 8.68 9.10

s. 16 5.91 7.72

8."38 7.48 a. 2a

10.43 8.48 9.54

10.23 8.00 9.2:3

6.35 6.1:2 e.. 24

4.59 a. 70 6.42

G. 39 9. 23 7. 72

~. 39 7.13 6.18

4.09 7. 61 5.66

0.00 -0.65 o. 00 -0.62 o.oo -o. 64

o. 0(1 1). 65

1). 00 -2. 14 o. oo -o. 59

0.00 -1.08 o. 00 -1. 18 0.00 -1.13

o.oo -1.37 o. 00 -0.95 o.oo -1.18

o. 00 o. 48 0.00 -1.81 o. 00 -0.55

y

DRY UTILISABLE

VENEER

57.30 54.91 56.21

55.44 60.03 57.48

60.54 63. 4G 61.90

6~.76

65.05 G5.44

57.04 64.36 60.32

04-May-83 at 14 • 11

DIAMETER MAXIMUM CYLINDER

(CM)

39.24 35.98

42.80 39.38

43.80 42.64

47. 16 43.5£

47.12 Mi,.Oe.

VENEER OUTTURN AS A PERCENTAGE OF ROUND VOLUME NOT ADJUSTED - TOTAL

AN

47. 1 20.3 34.8

24.9 20.7 23.0

13.6 2. 2 8. 3

2.5 8. 7 5.4

8. 9 25.1 16.2

A

2.2 7.6 4.7

0.0 2.5 1.1

2.3 0.0 1.2

0.0 0.0 0.0

2.9 3.6 3.2

B

4.9 1.5 3.4

5.8 G.3 G. 1

1G.a 4.9

11.3

15.4 12. 1 13.9

4.2 2.2 3. 3

CP

3.1 10.2 G.3

7. 9 5.8 7.0

13.7 18.4 15.9

2G.4 22.7 24.7

32.0 10.7 22.5

c

0.0 12.7 5.8

7.9 7.4 7.7

14.2 32.3

· Z2.7

19.6 13.3 16.8

6.2 21.0 12.8

D

o.o

1.2

a. a 17.4 12.6

o.o 5.6 2.6

1. 7 8.2 4. 7

2.9 1.8 2.4

TOTAL

55.4 50.0 57.5

60.5 53.5 61.9

65.8 G5. 0 65.4

57.0 64.4 &0.3

36

PEELER - PARf\/PARSONS TABLE 4 CONVERSION OF GREEN LOGS TO DRY UTILISABLE VENEE:R

LOG BOLT

13 A B

TOTAL

15 A B

TOTAL

!5 A B

TOTAL.

17 A B

TOTAL

18 A B

TOTAL

AN

62.78 22.'34 85.72

36.20 24.02 60.22

19.95 2.88

22.83

4.22 12. ;~a 15.50

17.70 40.54 58.:24

AREA OF VENEER IN SQ M NOT ADJUSTED - TOTAL

A

2.88 8.64

11.52

f). (H)

2.88 2.88

3.31 0.00 3.31

0. (H)

0.00 o.uo

5.76 5.7E.

11.52

B

6.57 1. 5'3 8.25

8.47 7.3(;

15.82

24.70 5.37

31.07

25.91 15.98 42.90

8.28 3.51

11.79

CP

4.09 11.52 15.61

11.52 6.69

18.21

20. 16 23.74 43.90

44.38 3l. ()2 7b .. 2(J

63.60 17.28 80.88

PEELER - PARt\/PARSONS TABLE 5

LOG BOLT AN Full$ 2.00 Part $ 2. 00

13 A 125.55 B 45.88

TOTAL 171. 44

15 A 72.40 B 48.05

TOTAL 120.45

16 A 39.'30 B 5.76

TOTAL 45.66

17 A 8.44 B 24.56

TOTAL 33.01

18 A 35.41 B 81.08

TOTAL 115.49

CONVERSION OF GREEN LOGS TO DRY UTILISABLE VENEER

VALUE OF VENEER IN DOLLARS NOT ADJUSTED - TOTAL

A 1. 86 1. 86

5.36 16.07 21.43

0.00 5.36 5.36

6.16 0.00 6.16

0.00 o.oo o.oo

10.71 10.71 21.43

B 1. 62 1. 62

10.65 2.74

13.39

CP 1. 3G 1. 36

5.56 15.67 21.23

13.71 15.57 11.92 9. 10 25.63 24.76

40.01 27.42 10.32 32.29 50.33 59.71

41.98 60.36 27.51 43.27 69.49 103.63

13.42 86.50 5.68 23.50

19. 10 110.00

c 1. 10 1.10

o.oo 15.84 15.84

12.67 9. 51)

22. 18

22.99 45.93 58.92

36.26 20.62 55.88

13.44 37. 16 50.61

D 0.94 0.94

0.00 2. 71 2.71

12.00 18.95 30.95

OeOO 6.74 6.74

2.71 10.83 13.54

5.41 2.71 8.12

TOTAL

147. 12 98,91

246.03

126e45 10'2.88 229.33

136.48 101.04 237.52

149.75 126,80 276.55

164,89 160.86 325.75

c

OeOO 14.40 14.40

11. 52 8.64

20.15

20.90 41.76 62.55

32.96 18.75 51. 71

12.22 33.79 46.01

D

0.00 2.88 2.88

12.76 20. 16 32.92

0.00 7. 17 7.17

2.88 11.52 14.40

5.75 2.88 8. 6f•

TOTAL

75.32 62.07

138.39

80.47 5'3.75

150.22

89.02 81.92

170.94

110.36 91.35

201.71

113.33 103.76 217.09

VALUE OF RESIDUES

GREEN CORE

2.26 2. 18 4.44

2.21 2.26 4.46

2.23 2.23 4.46

2.23 2.23 4.46

2.21 2. 31 4.51

WASTE

0.97 0.87 1. 85

1. 20 o.a:s 2.05

1.03 0.74 1. 77

0.87 0.72 1.59

1. 74 1.05 2.7'3

04-M&y-83 •t 14111

TOTAL VALUE

$

150.35 101. 96 252.31

12'3.86 105.98 235.84

139.74 104.01 243.75

152.85 129.75 282.60

168.84 164.21 333.05

S/m3<r>

355.44 284.01 322.64

281.69 287.22 284.15

29'3.23 253.69 277.'34

286.77 2'30.91 288,66

267.58 320.72 291.39

37

SECTION 2 - GRADING VENEERS FROM PHOTOGRAPHS

(J. Firth and W.A.J. van Dijk)

2.1 INTRODUCTION

Whenever veneer grading studies are carried out, considerable time can be spent in the factory measuring and recording the defects. Furthermore, the shape and distribution of some defects can be· particularly difficult to describe adequately. Some time ago the suggestion was made that it might be possible to use photography to speed up and aid the grading process. Trials . were initiated using various films and lighting arrangements and a technique developed whereby the grading could be done from colour transparency photographs of the veneers.

2.2 METHOD

The method involved laying the veneers one by one on a specially designed light table on the factory floor and photographing them with a camera mounted in the factory roof. About 200 sheets an hour can be photographed this way. Fig. 2.1 and Fig. 2.2 show the arrangement used.

DUAL FLUORESCENT LIGHTS WITH REFLECTOR //1

55 mm FORMAT CAMERA WITH 80 mm LENS MOUNTED ~IN ROOF OF , l( FACTORY

I \ I \

I \/ I /\

I / \ I / \

( / \4000 mm

/ \ /I \

PUSH BUTTON LEAD TO FIRE CAMERA

I I

I I

I

4' FLUORESCENT TUBE WITH REFLECTOR

VENEER SUPPORT TABLE WITH ADJUSTABLE LEGS

I I I ~

I I

I

FIG. 2.1 - Arrangement for taking photographs

38

GRADING SCALES

\oo 00 00 00 0 0

VENEER -PALLET .. TABLE .. PALLET

FIG. 2.2 - Plan showing movement of veneers

After processing, the film was joined into 100-ft lengths and then loaded into a modified projector and the grading done on the projection screen, as indicated in Fig. 2.3.

...... ......

ROLL OF FILM

VENEER GRADING ~ DONE ON SCREEN ""V

....... .......

.......

PROJECTION SCREEN --~·~ .... "' "'

FIG. 2.3 -Arrangement for grading veneers

Provided that the film/veneer plane and the projector/screen plane are kept parallel, measurement errors resulting from tilt displacement are avoided.

39

2.3 TECHNICAL DETAILS

2.3.1 CAMERA

The camera used was motorised and had a medium (55-mm) format for optimum resolution. If this format is not available, a motorised 35-mm camera would probably suffice. Care must be taken to ensure that the push button lead does not get into the field of view of the camera. A relay may be needed if the push button lead becomes too long. A counter is attached to the push button.

2.3.2 FILM

The film type used for the study was 70-mm colour transparency film housed in 70-frame magazines. Either 220 or 120 film can also be used but more time would have to be spent changing the magazines. Black and white and colour infra-red films were tried but did not reveal features such as compression wood, dry patches, and sap stain as well as true colour film.

2.3.3 CAMERA MOUNT

The camera was rigidly attached to a bracket on a pipe in the factory roof and was levelled with a level bubble before use. If the camera is not level, the image will take on a trapezium shape and measurement errors may be introduced.

2.3.4 LENS

An 80-mm focal length lens was used in the camera with the result that a 2400-mm sheet of veneer fitted comfortably into the 55-mm frame when the camera was 4 m from the table top. The following formulae show the relationship between the coverage, scale, focal length, and height, so that a system can be designed for whatever conditions exist.

1 =

focal length

scale factor height from table top to lens

and

coverage = format x scale factor

2.3.5 LIGHTING

The veneer must be evenly ill umi na ted. Two overhead 5-ft-long dual fluorescent tubes were used for this purpose. The lights were offset to enhance the surface texture of the veneer. Green veneer should be lighted from beneath when photographed, while dry veneer is best

40

photographed using lighting that is above and to one side as well as beneath. Bottom lighting emphasises cracks, sap stain, compression wood, grain pattern, and type of knot, while overhead lighting enhances the surface texture.

2.3.6 VENEER SUPPORT TABLE

The veneer support table (Plate 2 .1) was rigidly constructed of open box aluminium girder. Where possible the sections were bolted together rather than welded to facilitate transportation. The legs were adjustable so that the height of the table could be altered for varying situations. The frame supporting the lights was attached by chains to hooks on the main frame so that its height could also be adjusted if necessary. Before the table was used, checks were made to ensure that it was horizontal and parallel with the film plane.

PLATE 2.1 -Veneer support table

2.3.7 VIBRATION

In a factory situation vibration from heavy machinery can cause blurr­ing of the photographic image. The presence of vibration was tested by placing a glass of water on the table and watching for ripples. If vibra­tion is a problem, either the equipment must be insulated with something

41

like rubber or the strength of the overhead lights increased to allow a faster shutter speed.

2.3.8 SCALING

A set of scales (Fig. 2.4) appropriate for the defect code being used was included on each photograph. They enabled the defects to be readily assessed regardless of the scale of the image on the projection screen.

FIG. 2.4 - Scale for defect code used

PLATE 2.2 -Modified projector for projecting film of veneers to be graded

42

2.3.9 SKIRT

The veneer light table had a black skirt around it from table top edge to floor to cut down on stray light and reduce operator eye fatigue.

2.3.1 0 PROJECTOR

The projector used (Plate 2.2) was a standard 70-mm model modified slightly to accept roll film.

2.3.11 COSTS

After the initial outlay for basic equipment, the only other cost for the photographic method was film and processing, which together amounted to about $0.60/frame for the 70-mm film used.

2.4 RESULTS

An important advantage of the photographic method is that an accurate, permanent record is obtained of each veneer sheet. This record contains far more information than is possible with the normal written description method and enables the veneers to be reappraised at any time and regraded to any new set of rules. The method proved equally suitable for green or dry veneer (Plates 2. 3 and 2. 4) and enabled the following to be seen and assessed easily:

* Knots - sound, unsound, and missing

* Cracks - large and hairline

* Sap stain

* Dry patches in green veneer

* Compression wood

* Grain pattern

Some measurements, such as area of sap stain or length of cracks, can be made more quickly on the photograph than on the veneer itself because of the more convenient size of the photograph.

By photographing the veneer wet and then again after drying, it is possible to distinguish between degrade already present in the bolt or caused by the peeling process and that caused or intensified by the drying process itself.

If the veneer is photographed in the sequence in which it came from the lathe, the photographs make it much easier to reconstruct the original log and to study the spatial and temporal relationships of defects such as resin pockets and adventitious shoots.

43

Plate 2.3 - Photograph of green veneer sheets

Plate 2.4 - Photograph of dry veneer sheet

44

The technique described in this paper is designed primarily as an aid for veneer grading studies. Commercial grading done in the factory would probably not normally benefit from such a system; however, photographs of selected veneers taken using this method would certainly be a valuable aid in training personnel to carry out commercial grading and would also act as a convenient standard.

ACKNOWLEDGMENTS

The author of Section 1 gratefully acknowledges the assistance provided by other members of the Radiata Pine Task Force in the pilot studies on pruned peeler logs that were used to derive the method presented here. Various methods of veneer description were tried, and the photographic method finally adopted originated from a suggestion by Or 0. Garcia. The applicability of this method for unpruned logs was tested by D.R. Page who also made useful suggestions for improvements to procedure. The co-operation and assistance of the management and staff of H.T. Plywood Ltd, Mount Maunganui, was essential to the development of this method. The contribution of R. de Vries and s. Lewis ·is also acknowledged.

The authors of Section 2 gratefully acknowledge the assistance of H.T. Plywood Ltd, Mount Maunganui, in allowing the use of their factory for this study.