Qhob thaiv cov pwm tuaj yeem yuav kav li ntawm 80000-10000 mus, tiam sis, qhov no yog nyob ntawm:
Raw khoom:
Yog tias raw khoom siv los ua cov pwm (piv txwv puag ncig dej xuab zeb thiab pebbles xws li hloov pob zeb). Cov pwm kev ua neej yuav puv, crush granite / pob zeb nrog cov tawv tawv yuav ua rau qhov pwm, ua rau nws lub neej tsis muaj zog, cov khoom tawv raw kuj yuav txo nws txoj sia.
Lub sij hawm kev vibration & siab:
Qee cov khoom yuav tsum muaj sijhawm ntau dua (yuav ua kom muaj zog zog ntawm cov khoom) qhov kev nce ntawm kev siv lub sijhawm ua kom qhov kev tuaj yeem ua rau cov pwm ua rau txo qis hauv nws lub neej.
Precision:
Qee yam khoom yuav tsum tau muaj kev txiav txim siab (piv txwv li pavers) uas cov pwm yuav tsis siv kom siv tsis pub dhau ib lub sijhawm. Txawm li cas los xij cov khoom siv tsis tseem ceeb (ie hollow block), qhov sib txawv ntawm 2 hli ntawm cov tuaj pwm tseem yuav pab kom cov pwm siv tau.
