The utility model discloses a dial formula
radius compasses, including the casing and the
handle connected at its top, install the dial on the casing, the center rotation of dial is connected with the central shaft, and the front end of central shaft is provided with the pointer, and the lower extreme of casing is rotatively connected with the pen nib
branch leg and the needle foot
branch leg of symmetrical distribution respectively, and one coaxial of pen nib
branch leg and needle foot branch leg is provided with the
locking mechanism, and pen nib branch leg and needle foot branch leg are connected with the central shaft
through transmission mechanism. The utility model need not ruler, and the operation is simplified: the synchronous linkage of branch leg and pointer is realized
through transmission mechanism, and the indication value of pointer on dial directly corresponds the
radius, need not the help of ruler measurement, reduces the operation step, and promotes the mapping efficiency, and the adjustment is convenient, and the operation is stable: the
radius adjustment can be realized through "manual break branch leg" or "auxiliary nut fine adjustment", and the cooperation of nut and extension screw rod, the elastic clamping design of protection cap all promote the operation stability, and save the labor and not easy to slip.