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Jim -- There are probably a dozen different types of reamers. The Home Depot reamer you have seen was almost certainly a "repairman's tapered reamer" which is used mainly to increase the diameter of existing holes in sheet metal . . . the holes end up being tapered to match the reamer (Well, sort of. The repairman's tapered reamer is operated and guided by hand so the hole it produces will probably be egg-shaped and tapered more than the reamer itself.) There are two fundamental types of reamers that are commonly used for precise holes: hand-driven reamers and machine-driven reamers. The hand reamers, which come in fixed-size and adjustable-size variants, have a very slight taper leading up to a cylindrical section on the cutting portion of the tool, followed by a cylindrical shank with a squared end to take a tap-and-reamer wrench. The machine reamers essentially come only in fixed-size models. The most common is termed a "chucking reamer" and has a short sharp 45-degree taper cutting edge leading to a cylindrical section that serves mainly as a guide for the cutting edge. These reamers do not have drive squares, as they are not intended to be driven by hand. I'd suggest that you find a machine-shop textbook (perhaps from the library) for a good basic explaination of reamers and reaming. Also, ENCO, MSC, and other mill-supply houses have on-line catalogs that would allow you to see pictures of these types of reamers. Any mill-supply house or Industrial Distributor can provide you with reamers, but only a few common sizes will be stocked. Even big-city mill supply houses normally have to special-order unusual-size reamers. For what it's worth, a lot of folks will round or champher the corners of a twist drill to create an improvised reamer for cleaning holes. These "drill reamers" are used much as a chucking reamer, and work best if machine guided (drill press or milling machine). In any case EXCEPT that of the repairman's tapered reamer, a reamer is NOT intended for heavy stock removal. The rule-of-thumb is to drill the hole 1/64 inch undersize and ream out the rest. Hope this helps. John
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