Kev Coj Ua Yuam Kev IV
1870s mus rau Ntiaj Teb Tsov Kuv
Lub tshuab dav universal milling ntawm xyoo pua 20th. Qhov tsim nyog rau cov cuab yeej ua haujlwm, kev siv haujlwm, lossis siv ntau lawm.
Nyob rau hauv cov xyoo no, Brown & Sharpe thiab Cincinnati Milling Tshuab Company dominated milling tshuab teb. Txawm li cas los xij, pua pua ntawm lwm lub lag luam kuj tau ua cov milling cov tshuab thaum lub sij hawm, thiab ntau yam tseem ceeb hauv ntau txoj hau kev. Dhau li ntawm ntau qhov tshwj xeeb cov cav tov ntau, cov qauv siv ntau qhov kev siv milling ntawm 19th thiab 20th centuries thaum ntxov yog qhov hnyav ntawm sab qaum-thiab-kem kab hlau rhaub tsim nrog lub hwj huam mov, indexing lub taub hau, thiab ib qhov chaw khwv nyiaj los txhawb lub chaw muag khoom . Cov evolution ntawm lub tshuab tsim tau tsav tsis yog los ntawm cov kev xav pom xwb tab sis kuj los ntawm cov evolution tas li ntawm milling cutters uas pom milestone tom qab milestone ntawm 1860 mus txog lub ntiaj teb ua tsov ua rog I. [26] [27]
