Types of Reamers for Precision Hole Finishing

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2. REAMING IN THE DRILL PRESS tab Reamers • Reamers are tools used mostly to precision finish,enlarge or align existing holes. There are two types of reamers: • Machine Reamers • Hand Reamers

3. REAMING IN THE DRILL PRESS tab Fig. H-106 The parts of a machine reamer (Besly Cutting Tools, Inc.). Machine Reamers • Machine reamers have straight or taper shanks. • The taper usually is a standard Morse taper.

4. REAMING IN THE DRILL PRESS tab Fig. H-107 Cutting end of a machine reamer (Besly Cutting Tools, Inc.). Common Machine Reamers • The cutting end of a machine reamer is shown.

5. REAMING IN THE DRILL PRESS tab Fig. H-108 Straight shank straight flute chucking reamer. Fig. H-109 Straight shank helical flute chucking reamer. Fig. H-110 Taper shank helical flute chucking reamer. Common Types of Machine Reamers • Chucking reamersare efficient in machine reaming a wide range of materials and are commonly used in drill presses, turret lathes, and screw machines. • Cut on the chamfer at the end of the flutes, usually at a 45-degree angle. • Helical flute reamers have extremely smooth cutting action to finish holes accurately & precisely.

6. REAMING IN THE DRILL PRESS tab Fig. H-111 Taper shank straight flute jobber’s reamer. Common Types of Machine Reamers • Jobber’s reamers are used where a longer flute length than that of chucking reamers is needed. • Additional flute length gives added guide to the reamer, especially when reaming deep holes.

7. REAMING IN THE DRILL PRESS tab The teeth are slightly backedoff, making the diameter smaller toward the shank end by about .001 in./in. of flute length. Lands are ground cylindrically without radial relief, & all cuttingis done on the end of the reamer. Fig. H-112 Rose reamer. Common Types of Machine Reamers • The rose reamer is a roughing reamer used to enlarge holes to within .003 to .005 in. of finish size. • Typically followed by a fluted reamer.

8. REAMING IN THE DRILL PRESS tab Fig. H-114Taper shank shell reamer arbor. Fig. H-113 Shell reamer helical flute. Common Types of Machine Reamers • Shell reamers are finishing reamers. • More economically produced than solid reamers because a smaller amount of tool material is used in making them. • Two slots in the shank end of the reamer fit over matching driving lugs on the shell reamer or box • The hole in the shell reamer has a slight taper of 1/8” per foot in it to ensure exact alignment with the shell reamer.

9. REAMING IN THE DRILL PRESS tab Fig. H-115 Morse taper reamer. Common Types of Machine Reamers • Morse taper reamers, with straight or helical flutes, are used to finish ream-tapered holes in drill sockets, sleeves, and machine tool spindles.

10. REAMING IN THE DRILL PRESS tab Fig. H-116 Helical taper pin reamer. Taper pin reamers have a taper of 1/4” per foot of lengthand are manufactured in 18 different sizes ranging from number 8/0 to number 10. Common Types of Machine Reamers • Helical taper pin reamers are especially suitable for machine reaming of taper pin holes. • Free-cutting action produces a good finish at high cutting speeds, and chips do not get packed in the flutes, which reduces the possibility of breakage.

11. REAMING IN THE DRILL PRESS tab Fig. H-117 Helical flute taper bridge reamer. Taper bridge reamers are made with straight & helical flutes to ream holes with diameters from 1 /4” to 1-5/16” Common Types of Machine Reamers • Taper bridge reamers are used in structural ironor steel work, bridge work, and ship construction where extreme accuracy is not required. • Long tapered pilot points make for easy entry in theout-of-line holes often encountered in structural work.

12. REAMING IN THE DRILL PRESS tab Fig. H-118 Carbide-tipped straight flute chucking reamer. Fig. H-119 Carbide-tipped helical flute chucking reamer, right-hand helix. Common Types of Machine Reamers • Carbide-tipped chucking reamers are often used in production setups, particularly where abrasive materials or sand & scale are encountered. • A right-hand helix chucking reamer is recommended for ductile or highly abrasive materials, or when machining blind holes.

13. REAMING IN THE DRILL PRESS tab Fig. H-120 Carbide-tipped helical flute chucking reamer, left-hand helix. Common Types of Machine Reamers • A carbide-tipped left-hand helix chucking reamer will produce good finishes on heat-treated steelsup to RC 40. • These reamers should be used only on through holes,as chips push out through the hole ahead of the reamer.

14. REAMING IN THE DRILL PRESS tab Fig. H-121 Carbide-tipped expansion reamer. Common Types of Machine Reamers • After becoming worn, expansion reamers can be expanded and resized by grinding. • This offsets normal wear from abrasive materials & prolongs long tool life. • They should not be adjusted for size by loosening or tightening the expansion plug, but only by grinding.

15. REAMING IN THE DRILL PRESS tab Hand Reamers • Various types of hand reamers are • Straight fluted • Expansion • Adjustable

16. REAMING IN THE DRILL PRESS tab Speeds • Cutting speeds, which generally depend on: • Type of material being reamed. • Amount of stock to be removed. • Tool material being used. • Finish required. • Rigidity of the setup. • The reaming speeds for most materials are about two-thirdsof the speed used for drilling.

17. REAMING IN THE DRILL PRESS tab Speeds • Class Activity: • Calculate the speed for rose chucking reamer if 12 mm diameter of HSS drill used to make the hole on Aluminum plate and cutting speed is 92m/min?

18. REAMING IN THE DRILL PRESS tab Feeds • Feeds in reaming are usually two to three times greater than those used for drilling. • Feed varies with different materials, but a good starting point would be between .0015 &.004” per revolution. • Too low a feed may “glaze” the hole, work hardeningthe material, causing chatter & excessive reamer. • Too high a feed tends to reduce the accuracy of thehole & quality of the surface finish.

19. REAMING IN THE DRILL PRESS tab Mild steel & some aluminum alloys are particularly troublesome inthis area. Fig. H-123 Reamer teeth having built-up edges. Reaming Problems • When reamers gradually start cutting larger holes, work material may be galling or forming a built-up edge on reamer cutting surfaces.

20. TAPS IN THE DRILL PRESS Taps • Used to produce internal threads. • The drill press may be used for either hand or machine tapping. • Hand tapping is generally used when only a few holes are to be tapped. • Machine tapping is preferred when many holes must be tapped.

21. TAPS IN THE DRILL PRESS Types of Taps • (1) Hand Taps : are available in sets containing three taps: • Taper, • Plug, and • Bottoming

22. TAPS IN THE DRILL PRESS Types of Taps (2) Machine Taps : used with power Gun taps Stub-flute tap Helical-fluted taps or Spiral-fluted taps 4. Flute less tap Cutting Action

23. TAPS IN THE DRILL PRESS Tap Drill Size (TDS): INCH : Q. Calculate the tap drill size required for a 1-in. -8 NC thread.

24. TAPS IN THE DRILL PRESS Tap Drill Size (TDS): Metric Taps Metric taps are identified with the letter M followed by the nominal diameter of the thread in millimeters times the pitch in millimeters. Tap Drill Sizes for Metric Threads The tap drill sizes for metric threads may be calculated by subtracting the pitch from the nominal diameter. T.D.S. = D - P For example: Calculate the tap drill size for an M12 X 1.75 thread. T.D.S. = 12 - 1.75 = 10.25 mm

25. REAMING IN THE DRILL PRESS tab Speeds • Class Activity: • Calculate the tap drill size for an M10 x 1.25 threads?

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