Umbhobho luhlobo lwengcindezi, futhi uketshezi kumele lube ngaphansi kwengcindezi yokusebenza ngokujwayelekile. Lolu hlobo lwesesekeli lungaveza ukuma kwesifutho se-engeli egcwele-isigcawu nge-angle yokufafaza engaba ngu-20 ° -40 °. Lesi sesekeli sisekela ukwenza ngokwezifiso, sicela uxhumane nathi.