In Bangladesh mostly plastic limit test of soil is performed by repeated rolling of an ellipsoidal-size soil mass by hand on a glass plate which is time consuming and conscientious one. So that this study is to introduce and assess the effectiveness of an alternative method BS 1377(Thread rolling method) other than Casagrande's and cone penetrometer method for local soil plastic limit test.However, a plastic limit rolling device was fabricated with laminated celluloid glass. It was observed that rolling device worked perfectly and can get an exact crumbling point for loamy and clay soil.Clay index was introduced to show the relationship of sample soil with consistency limits.For loamy to clay soil liquid limit value ranges from 32 to 44.3 % in Casagrande’s method while in cone penetrometer is 34.5 to 53.5%. A crucial point of clay index 5% has been determined where both the method provides same results for sandy soil.For loamy soil, plastic limit value obtained by standard method, rolling device method and cone penetration provides 23 to 25.28%, 20 to 24.34 % and 19.5 to 23% respectively. This analysis should be useful to professionals in soil and foundation engineering fields.