Product Manual

Fig. 11
Fig.12
Determine u- value with formula:
A
T
u = -------- ; where A
T
= size of
N of test area.
Example :
If your test area is a 4 x 4 inch square,
and the readout result was 1725, then
your new u-value is
16
u = ------ = 0.00927 in
2
1725
Use the same procedure to deter-
mine new u-values for the medium
and long tracer arm.
Record the new u-values.
Page 10
8. THE COMPENSATING FEATURE
To compensate for tracing errors, it is advis-
able to measure areas twice and to use the
average of both results.
To compensate for instrumental and tracing
errors, you may want to employ the compen-
sating feature of your instrument.
The area of a figure must be measured first
with the tracer point to the right of the pole arm, (Fig.11) and then with the tracer point to the
left of the pole arm. (Fig.12) The position of the pole weight must be identical for both
measurements.
The readout results must subsequently be averaged.
9. TIPS AND HINTS
Lasico Planimeters are no longer calibrated for the inferior "Pole inside the figure " method,
which provided a larger measuring range.
Instead we recommend to subdivide areas which cannot be measured in one continuous
operation, into smaller sections and to measure them separately.
Avoid extreme temperature conditions, since material expansion or shrinkage (of both in-
strument and drawing) can cause sizable measuring errors.
If a planimeter was stored at low temperatures, loosen up its measuring mechanism by
moving the instrument around in a circular motion until the measuring wheel rotates freely.
The length of the pole arm does not affect the result of a measurement. Therefore you can
set it to any extension desired. A longer pole arm provides a larger measuring range.
To protect the instrument and especially the delicate needle bearings from damage, al-
ways lower the planimeter gently onto the table surface. Keep the instrument in its protec-
tive case if it is not used.
Protect it from dust, dirt and excessive humidity and do not touch the rim of the measuring
wheel. The measuring wheel must always spin freely.
If dust accumulates anywhere in the measuring mechanism or the ball socket of the pole
arm, remove it with a Q-tip . Apply a few drops of fine watch oil to bearings and ball sockets
every 2 years.