Copyright 2002 Silvi-Crew Ltd.
SILVI-CREW LTD SPACING SAW TRAINING PROGRAM: MODULE 9
SPECIAL CUTTING CONSIDERATIONS
OBJECTIVES
This module is designed to instruct the student in the methods of dealing with special cutting problems. Also examined are the effects of stand development on work technique and subsequent overall job quality.
PREREQUISITES
MATERIAL COVERED
STUDENT PERFORMANCE EVALUATION
Each student must identify and describe particular difficulties incurred and demonstrate appropriate corrective measures. The students must also appreciate the dynamic process of stand development and its effects on precommercial thinning.
RESOURCE MATERIALS
Special cutting problems
a. cutting with the kick back zone œ Many trees below two inches in diameter may be cut with the kick back zone. Experienced operators utilize this technique very efficiently. This method must not be used when potential crop trees lie to the immediate right. These trees will not escape damage from kickback. However because the kickback forces also displace the stem from the stump, this action is used frequently.
b. Hardwood clump - clear felling area - tilt blade and cut stems waist high - displace stem into uncut areas - recut stump and top - cut in order always felling into open areas (dfmn).
c. Leaning trees Cut a small, sliced front notch with the lean, (< 1/2 diameter) then cut backcut. rocky ground. Some trees require two cuts to expose any rocks, first cut above the general height of the rocks and then the second, when you can see.
d. Bring extra blades and change when you hit rock bad, but always get the most out of your blades. Take them home at night and file them up. Some have changed the filing stroke to that of a semi-chisel, to give more cutting surface.
e.Little trees - little trees and those with low live green branches only create problems in some areas. Small trees really become a problem in stands with low dominant height and/or wider spacings. Since not all little trees will seen by the operator, all that are seen must be cut. If this is done then missed little trees should not get out of hand.
f. Work your face up hill back and forth across the slope. Cut trees easily fall down slope into the thinned area.
g. Large sized trees Select best crop trees at wide spacing, this provides adequate felling space. Double cut trees high enough for the crown to fall out of the canopy, and fall all by themselves. Of coarse as much as possible, larger trees should be selected as crop trees.
h. Wounded crop trees. Usually a spacing problem. The trees are spaced too close and there is no room for the thinner to turn around. This problem also results from cutting with the kick back zone, endangering crop trees to the immediate right. Also a problem with small crop trees and care must be taken not to cut the top off of the crop tree. If crop trees are wounded while pulling down cut trees, the left hand should be used to pull down trees while the right hand pulls up on the handle of the saw thus causing the blade to be aligned vertically. In this position it is very hard to wound other crop trees. In nearly every case, any crop tree that has been wounded must be cut and another selected.
On Site Size Variabilities
a. touch and cut stems (0-4 cm) as always " sharp blade " why? Any part of the sawblade may be used - trees easily cut by speed alone (Explain: Dull blades cut!) - best cutting employs use of blade rotation - best cutting by sweeping motion across the workface in thick cutting when crowns are interwoven, fell trees in groups - follow through when scything - usually large stem displacement required - fell trees in the right order to avoid hangups etc. - pay heed to spacing, usual tendency is tight spacing - pay heed to small trees and high stumps with low live green branches - avoid missing small trees and getting them between the rear of the blade and guard and your feet
b. Medium sized stems (4 - 8 cm) - trees are still small enough to be cut with one swipe - blade rotation lots to drop single trees - single stem cutting requires a quick swipe at full speed - usually each stem must be cut separately, but again they fall better in groups - feed direction, hip thrusts and follow through important - sweeping motion can fell groups - 10 - 11 o`clock area of blade for precise cutting - utmost care required while cutting with kickback zone - leaners cut with one swipe on back side
c. Larger double cuts (8 -15cm) - these trees may require front & back cuts - blade tilt more important than rotation, simply due to size of stem diameter, and weight of crown - tilted front and back cut - cutting height also very important, crown will drop out of canopy ensuring good stem displacement - wider spacing enables ease of cutting in high density stands - larger trees require larger front notch - order of felling most important, don`t fight mother nature (dfmn), fell trees as they are ready to go - wind direction very important - (dfmn) - lean and crown shape - ensure sharp blade at top speed and allow normal feed - avoid cutting with kickback zone as blade can not cut all the way though and will jar abruptly
Stages of Stand Development
Composition of Stand Development
problems with mixedwood stands - selection of smaller softwoods - danger of burying small crop trees - hardwood crowns interwoven with softwood - wide spacing must be used - variable spacing must be used
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Last Updated 02/18/2004