Studies on Trial Piano-Wire Blade for Bush Cutter (1)

Trial and Determination of Specification

Abstract

Experiments were carried out to determine the construction specification of trial flail type pianowire blade.
The results of experiments were summarized as follows:
1. For better mowing, the most appropriate shape of piano-wire blade was of the disc diameter of 100mm, the wire diameter of 3.2mm with 8 pieces of wire of wire length of 70-100mm, respectively.
2. The flail type piano-wire blade was least abrasive under mowing work. An endurance test using concrete panel showed that it was not broken, but the tip of blade was worn out about 30mm against 5×10⁴ blowing. Piano-wire blade could satisfactorily mow grass growing near concrete fence.
3. Piano-wire blade had an advantage over cut-away blade in rate of work and fuel consumption.
4. It was considered that the most desirable edge shape of piano-wire blade tip was of wedge angle of 90°.
5. An increase in abrasion of cut-away blade, resulted in an increase in cutting angle and large diminution of working rate.
Even if the blade was shaped ground, recovery of cutting quality was hardly possible.
6. Higher operating efficiency was indicated (edge shape of) at the wedge angle of 90° than that of 30°. In the case of high speed, the attempt of giving an edge to cut-away blade was made.
7. Nylon-wire blade was able to mow with safety, but we had difficulty to cut off grass as a result of shortening nylon wire.
8. We feel from the experiment described above that the piano-wire blade had possibility of practical use.