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| All Patents in class 175/421 | |||||
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| Number | Date | Patentee | Title | Type | |
| 410,311 | Sep. 03, 1889 | M.T. Chapman | Expansion Drill | well drilling machines | |
| 632,764 | Sep. 12, 1899 | J. Stephens | Hollow auger | hollow bits | |
| 900,044 | Sep. 29, 1908 | N.E. Swanson | Hollow Auger | hollow bits | |
| 1,268,474 | Jun. 04, 1918 | J.G. Kilgore | Drill Bit | ||
| 1,273,724 | Jul. 23, 1918 | J.D. Boughner | Drill Rod Connection | ||
| 2,919,902 | Jan. 05, 1960 | M.J. Steffes | Masonry drill | ||