an 34 end down 34 break when the spinning tension exceeds the strength of the core component of the yarn insufficient gripping force should be avoided because it will allow too much of the twist to flow back up into the fiber assemble zone between the gripper nip and the front roller nip which leads to the undesirable barber pole effect generally the twist should flow back about 20 to 40 of the distance along the core strand from gripper nip to front roller nip the following are exemplary gripping forces for specific materials and wind up spindle speeds ______________________________________wrap core yarnmaterial material count spindle speed grip force______________________________________1 cotton polyester 20 1 10 000 rpm 10 grams2 cotton polyester 40 1 10 000 rpm 6 grams3 cotton cotton 20 1 8 000 rpm 8 grams______________________________________ the radius of curvature of surfaces at the gripper nip generally will range from about 1 2 34 to 1 34 depending upon yarn counts and types for a 20 1 yarn composed of cotton wrap polyester core a radius of curvature of 1 2 34 is suitable with regard to the operational speeds of the system of the present invention spindle speed may be the same as that employed to spin yarn of a given linear density and.