| US Patent: 930,620 
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| Combined breast-drill and valve-grinder | 
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| Patentee: |  |
 | John R. Sandberg (exact or similar names) - Denver, CO |  
 
 
 
 
| Manufacturer: |  | Not known to have been produced |  
 
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| Patent Dates: |  
| Applied: | Aug. 21, 1908 |  
| Granted: | Aug. 10, 1909 |  
 
USPTO (New site tip)| Patent Pictures: |  |  |  | Sandberg 930,620 |  Google Patents
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                        Steve Gosselin (GL)
 
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| Description: |  | John has designed a rather traditional style breast drill with a set of pawls. When one or the other of the pawls is engaged it gives the drill the reciprocal movement for valve grinding. |  |