كيف يتم عمل نجارة السلم الحلزوني؟

بالاعتماد على نواة مركزية يلتف حولها القالب اللازم لتنفيذ السلم الحلزوني

Gentleman,please ask me any question in English not in Arabic.If you ask question in English every one will also understand your question otherwise not!! I would also like to request "Bayt.com" to insist the candidate to ask question in English(or in both languages:English+Arabic).

Sir,please translate your question into English,so that i can atleast reply!Thanks.