用短鑽頭先鑽淺孔，然後把稍長鑽頭放入孔中後夾緊接著鑽，再換更長鑽頭放入孔中，夾緊，接著鑽，直到9”深，需多個鑽頭

來源: osch1130 於 2023-04-05 19:09:50 [舊帖] [給我悄悄話] 本文已被閱讀：次

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