cant amount of internal decay. Thus, only
poles which DO NOT TEST GOOD
should be subsequently bored to
conclusively establish the presence and
extent of decay or identify the cause of
the "bad reading.'
poles which DO NOT TEST GOOD
should be subsequently bored to
conclusively establish the presence and
extent of decay or identify the cause of
the "bad reading.'
3.2.2. Boring.-Boring a pole at the
locations where "bad" soundings were
obtained will clearly establish the type and
extent of decay. Not only are the
materials removed from the bore hole
significant, the borer as it penetrates the
wood is equally significant.
locations where "bad" soundings were
obtained will clearly establish the type and
extent of decay. Not only are the
materials removed from the bore hole
significant, the borer as it penetrates the
wood is equally significant.
When boring, notice that once the boring
instrument has obtained a purchase on
the wood, considerable effort is required
to turn the instrument; however, the bit
will advance without external pressure.
Less effort may be required as the bit
penetrates because of the increasing
moisture content of the wood; however,
an abrupt reduction in force required to
turn the instrument may indicate that the
bit has entered wood in the early stages
of decay.
instrument has obtained a purchase on
the wood, considerable effort is required
to turn the instrument; however, the bit
will advance without external pressure.
Less effort may be required as the bit
penetrates because of the increasing
moisture content of the wood; however,
an abrupt reduction in force required to
turn the instrument may indicate that the
bit has entered wood in the early stages
of decay.
Eventually, the bit may cease to penetrate on its
own because of complete loss of purchase. Ad-
ditional pressure on the bit may be necessary to
maintain its advance into the decayed wood.
Wood in the advanced stages of decay will allow
the bit to penetrate it by pressure alone.
own because of complete loss of purchase. Ad-
ditional pressure on the bit may be necessary to
maintain its advance into the decayed wood.
Wood in the advanced stages of decay will allow
the bit to penetrate it by pressure alone.
3.2.2.1. Precautions when boring.-
(1) Keep boring instruments sharp. As
bits become dull, the more difficult it
is to distinguish between sound and
decayed wood.
bits become dull, the more difficult it
is to distinguish between sound and
decayed wood.
(2) In certain cases where the sonic
tester does not clearly indicate the
outline of internal defects, several
borings may be necessary to
determine how far various stages of
decay extend within the pole.
tester does not clearly indicate the
outline of internal defects, several
borings may be necessary to
determine how far various stages of
decay extend within the pole.
(3) Wood texture, color, and moisture
content vary greatly in poles so that
no single set of distinguishing
characteristics can be applied to all
poles.
content vary greatly in poles so that
no single set of distinguishing
characteristics can be applied to all
poles.
Figure 3. The Poi-Tek sonic tester.
(4) Since collections of shavings during
boring of poles in the field are difficult, stop
boring as soon as a suspicious area is
reached and remove all shavings to that
point for examination. Continue boring by
stages to facilitate the removal of unmixed
shavings.
boring of poles in the field are difficult, stop
boring as soon as a suspicious area is
reached and remove all shavings to that
point for examination. Continue boring by
stages to facilitate the removal of unmixed
shavings.
(5) Treat and plug all holes to prevent
infection of sound poles.
infection of sound poles.
3.2.2.2. Interpreting the boring materials.-
Shavings removed from sound wood usually are
uniform in size, fibrous, and require considerable
force to break. As decay becomes more
advanced, a higher proportion of fines appear
mixed with the shavings, which become
progressively easier to crumble. Advanced decay
usually results in particles of small size that lack
cut surfaces and tend to pack in the flutes of the
auger.
Shavings removed from sound wood usually are
uniform in size, fibrous, and require considerable
force to break. As decay becomes more
advanced, a higher proportion of fines appear
mixed with the shavings, which become
progressively easier to crumble. Advanced decay
usually results in particles of small size that lack
cut surfaces and tend to pack in the flutes of the
auger.
Cores removed with an increment borer usually
remain intact until advanced stages of decay are
reached. Earlier stages of decay may be
determined by breaking off sections of the core
and crumbling them between the fingers. Sound
wood retains much of its fibrous nature, is
difficult to tear apart, and does
remain intact until advanced stages of decay are
reached. Earlier stages of decay may be
determined by breaking off sections of the core
and crumbling them between the fingers. Sound
wood retains much of its fibrous nature, is
difficult to tear apart, and does
(FIST4-6) 4