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There are hand reamers and machine reamers. They mainly differ with respect to the shank (hand reamer: square, machine reamer: taper) and to the cutting portion (machine reamers have a shorter lead).
Figure 1 Hand reamer, straight
1 lead, 2 finishing cut
Figure 2 Machine reamer, straight
1 lead, 2 finishing cut, 3 cutting portion reducing in diameter
Hand reamers are primarily used for assembly work to make parts fit better. Their main feature is a long taper lead. This ensures good guidance in the hole and prevents canting. The reamer is inserted into the hole by means of the milled square and a tap wrench with clockwise rotation and slight pressure.
Figure 3 Hand reamer in operation
1 feed movement, 2 cutting movement, 3 workpiece, 4 clamping tool (vice)
Dimensional inspection of reamers must be made at the transition to the straight portion (Fig. 1).
Hand reamers are non-adjustable (Fig. 1) or adjustable (Fig. 4).
Figure 4 Adjustable hand reamer
1 conical adjusting screw, 2 slot for expanding the diameter
Taper hand reamers are also in use (Fig. 5).
Figure 5 Hand reamers, tapered
What are the main differences between hand reamers and machine
reamers?
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Machine reamers used on lathes are: non-adjustable reamers (Fig. 2), arbor-mounted reamers (Fig. 6), adjustable reamers (Fig. 7), spiral-fluted reamers (Fig. 8) and taper reamers (Fig. 9)
Figure 6 Arbor-mounted reamer (shell
reamer)
1 cutting portion, 2 mounting arbor
Figure 7 Adjustable machine reamer
(1) for through holes; (2) for blind holes
1 blades in angular position, 2 adjusting thread, 3 adjusting cone, 4 re-adjusting nut
Figure 8 Spiral-fluted reamer
Figure 9 Machine reamer, tapered
Arbor-mounted reamers (20 mm diameter and more) and adjustable reamers are mainly used for reaming of several holes in a single set-up and for bigger quantities (easily interchangeable and adjustable). Spiral-fluted reamers are used for grooved holes and taper reamers for taper holes.
Adjustable reamers are to be checked for dimensional accuracy by means of the setting collar as per Fig. 10.
Figure 10 Setting (checking) of reamer
by setting collar
1 reamer blades, 2 setting collar (ring gauge)
Machine reamers are used for reaming on drilling machines and lathes. They are guided by the work spindle. Therefore, the lead need not be as long as that of hand reamers. With reaming, cutting is by the lead while the straight portion serves for smoothing the hole.
In order to avoid vibration patterns on the surface of the work-piece (chatter marks), reamers have non-uniform tooth pitches. This avoids vibrations and results in exactly round holes. The even number of cutting edges permits dimensional inspection (by outside micrometer) over opposite sides.
What types of machine reamers are used for
reaming?
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When are spiral-fluted reamers
used?
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