REAMERS A reamer is a metalworking tool used to create an accurate sized hole. The process is called reaming. They may be used as a hand tool or in a machine tool, such as a milling machine or drill press.
REAMERS MAIN PARTS: -Shank -Body -Angle of Chamfer
Recommended stock allowances for Reaming: Hole Size Allowances in. mm in. mm 1/4 6.35 .010 0.25 1/2 12.7 .015 0.38 3/4 19.05 .018 0.45 1 25.4 .020 0.5 1 1/4 31.75 .022 0.55 1 1/2 38.1 .025 0.63 2 50.8 .030 0.76 3 76.2 .045 1.14
TYPES OF REAMERS: 1. According to Shank: a. Straight b. Taper 2. Ross reamer 3. Fluted reamer 4. Shell reamer 5. Expansion reamer 6. Adjustable reamer
According to Shank: -Straight reamer (precision) A straight reamer is used to make only a minor enlargement to a hole. The entry end of the reamer will have a slight taper, the length of which will depend on its type. This produces a self centering action as it enters the raw hole. The larger proportion of the length will be of a constant diameter.
-Taper reamer (precision) A precision tapered reamer is used to make a tapered hole to later receive a tapered pin. A taper pin is a self tightening device due to the shallow angle of the taper. They may be driven into the tapered hole such that removal can only be done with a hammer and punch. They are sized by a number sequence. Such precision joints are used in aircraft assembly and are frequently used to join the two or more wing sections used in a sailplane. These may be re-reamed one or more times during the aircraft's useful life, with an appropriately oversized pin replacing the previous pin.
Ross reamer A rose reamer has no relief on the periphery and is offset by a back taper to prevent binding. They are primarily used as roughing reamers. The teeth on the end have a 45 degree chamfer that is backed off to produce the cutting edge.
Fluted reamer Fluted reamer have more teeth than ross reamer for a comparable diameter. The lands are relieved for the entire length, and fluted reamer therefore cut along the side as well as at the chamfer on the end. These reamer are considered finishing tools and are used to bring a hole to size.
Shell reamer Shell reamers are designed for reaming bearing and other similar items. They are fluted almost their whole length. Shell reamer heads mounted on a driving arbor. The shank of the driving arbor may be straight or tapered, depending on the size and type of shell reamer used.
Expansion reamer Expansion reamer are similar to adjustable reamers; however, the amount they can be expanded is limited. The body of this reamer is slotted and tapered, threaded plug is fitted into the end. Turning this plug will allow a 1 inch (25mm) reamer to expand up to .005 in. (0.12 mm). Expansion reamers are not meant to be oversize reamers but to give longer life to finishing reamers.
Adjustable reamer An adjustable hand reamer can cover a small range of sizes. They are generally referenced by a letter which equates to a size range. The disposable blades slide along a tapered groove. The act of tightening and loosening the restraining nuts at each end varies the size that may be cut. The absence of any spiral in the flutes restricts them to light usage (minimal material removal per setting) as they have a tendency to chatter. They are also restricted to usage in unbroken holes. If a hole has an axial split along it, such as a split bush or a clamping hole, each straight tooth will in turn drop into the gap causing the other teeth to retract from their cutting position. This also gives rise to chatter marks and defeats the purpose of using the reamer to size a hole.