Department of Mechanical Engineering;
Minxi Vocational & Technical College;
Longyan 364021;
P. R. China;
Department of Mechanical Engineering;
Xiamen Jimei Vocational Technology Educational School;
Xiamen 361022;
P. R. China;
Department of Mechanical & Electronic Engineering;
Xiamen University;
Xiamen 3610005;
P. R. China;
worm; helical; angle; coordinate; measuring; machines; measurement; uncertainty;