Faraanti ayaa hal dhibic kala jabay oo u foorarsaday qaab helical ah.Tani waxay keenaysaa in dhaqdhaqaagu uu sameeyo xoog guga inta u dhaxaysa madaxa xiraha iyo substrate-ka, kaas oo ku ilaalinaya dhaqdhaqaaga si adag uga soo horjeeda substrate-ka iyo dunta bolteedka si adag uga soo horjeeda dunta ama dunta substrate-ka, taasoo abuureysa khilaaf badan iyo iska caabin wareeg ah.Heerarka lagu dabaqi karo waa ASME B18.21.1, DIN 127 B, iyo Heerarka Militariga Mareykanka NASM 35338 (oo hore u ahaa MS 35338 iyo AN-935).