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Despite self levelling, fully automatic laser construction tools being around for decades, many builders and especially surveyors still prefer the good old, tried and tested dumpy level.
Although dumpy levels are considerably less expensive, I do not believe cost is the major motivation for investing in a dumpy level, or automatic level as it is more properly called.
The main reason is the belief in its quarter accuracy and control. The vertical cross hair shows that the staff is vertical, at least in one axis; while the metric staff reading in millimeters instead of the old E staffs with 10mm bars.
Few laser users employ Mabo Rods with a bullseye bubble for accurate measurement.
There is also the concern that more than one laser is being used on the site or an adjacent site that cen be picked up in error. This cannot occur with a dumpy level.
For surveyors taking many shots, the LEICA SPRINTER is proving very popular. It is essentially an electric dumpy level that is super accurate and provides digital distance measurement as well as elevation which can be downloaded from its memory. It may be regards as midway between a dumpy level and a builder's theodolite.
A dumpy level can measure distance by calculation from the stadia lines but this is a tiresome business and not very accurate.
Hence there are sound reasons why dumpy levels are still being sold in substantial numbers for use in building and construction. |
