Muaj ntau hom kev sib xyaw ua ke, suav nrog ob lub hau sib xyaw ua ke thiab peb lub qhov sib xyaw ua ke (pav ntxhua khaub ncaws thiab lub caij nplooj ntoos hlav ntxhua khaub ncaws lossis cais lub tshuab ntxhua khaub ncaws thiab lub caij nplooj ntoos hlav ntxhua khaub ncaws) raws li hom kev sib xyaw ua ke;Raws li lub taub hau hom, nws tseem tuaj yeem muab faib ua lub taub hau ua ke nrog cov ntsia hlau, countersunk taub hau ua ke screws, sab nraud hexagonal ua ke screws, thiab lwm yam;Raws li cov khoom siv, nws muab faib ua carbon steel, stainless hlau thiab hlau alloy (Qib 12.9).