Sutton 20.638mm Morse Taper Reamer (Machine) DIN208 HSS

The Sutton R101 is a machine reamer with a Morse taper shank, listed to DIN 208. It finishes drilled or bored holes to an H7 tolerance in a drill press, lathe or milling machine, and it is for toolroom and workshop use. It is HSS with a bright finish (uncoated and polished) and 10° left-hand flutes.

The range has 112 sizes from 6 mm to 50.8 mm: metric steps plus the common fractional-inch sizes from 1/4 in to 2 in. The shank steps up as the reamer gets bigger: MT1 for 6 to 14 mm (37 sizes), MT2 for 14.288 to 23.019 mm (34 sizes), MT3 for 23.5 to 31.75 mm (24 sizes) and MT4 for 32 to 50.8 mm (17 sizes). Flutes go from 6 to 12 with size (6 flutes at 6 to 13.891 mm, 8 flutes at 14 to 25.4 mm, 10 flutes at 25 to 35 mm and 12 flutes at 36 to 50.8 mm).

Where this product is used

• Machine finishing of drilled or bored holes to H7 in a drill press, lathe tailstock or milling machine fitted with a matching Morse taper socket or sleeve.
• Toolroom and workshop work where a repeatable, accurate hole matters, such as bearing housings, bushes and precision assemblies.
• Production and repair jobs where reaming by hand would be too slow.

Matching the shank to your machine

Check the Morse taper number of your machine spindle or sleeve before you order: tapers are not interchangeable between numbers. Gauge diameters above are from the Sutton Morse taper sleeve table; our Morse Taper Guide covers MT1 to MT6 sizes and compatibility.

Getting the best results on the machine

• Leave enough stock to cut. The starting guide for machine reaming is 0.20 mm for a 6 mm hole, 0.30 mm for a 12 mm hole and 0.50 mm for a 50 mm hole. Too little stock makes the reamer burnish rather than cut.
• Run slowly. The most efficient reaming speed is often about two-thirds of the speed you would drill the same material at, and the rule is that speed must not be high enough to permit chatter. Drop the speed again when you need close tolerance and a fine finish.
• Keep the feed up. Reaming feeds are usually much higher than drilling feeds: 0.038 to 0.10 mm per flute per revolution is a suggested starting point. Too low a feed can cause glazing, wear and chatter; too high costs accuracy and finish.
• Use straight cutting oil. In reaming the lubricant is chosen for finish rather than cooling, and that usually means a straight cutting oil.

Recommended starting surface speeds for reaming:

If it chatters or the finish is poor: Troubleshooting points first at speed and feed (both can cause breakage, wear, chatter and poor finish), then at dirt or burrs in the spindle or socket (a cause of breakage and chatter, fixed by cleaning the spindle), lack of rigidity, and a badly drilled hole. Clean the socket, check the rigidity of the set-up and check the pre-hole before changing anything else.

Fit and tolerance

H7 is the ISO 286 hole tolerance: never smaller than nominal and never larger than nominal plus the IT7 band (15 µm over 6 to 10 mm, 18 µm over 10 to 18 mm, 21 µm over 18 to 30 mm, 25 µm over 30 to 50 mm and 30 µm over 50 to 80 mm). Sutton holds the cutting diameter of its parallel reamers to M6 limits (BS 122 Part 2), chosen to produce H7 holes. For example, a Ø8 mm reamer has cutting diameter limits of Ø8.006 to Ø8.015 mm and the finished hole is held within Ø8.000 to Ø8.015 mm (H7); a Ø16 mm reamer has cutting diameter limits of Ø16.007 to Ø16.018 mm and the finished hole is held within Ø16.000 to Ø16.018 mm (H7).

Key specifications

Related reaming tools

Smaller jobs or no drill press? The R100 hand reamer is a fixed-size reamer you turn by hand, and the cobalt R102 chucking reamer suits a chuck. For holes that need aligning in fabricated work, see the R104 bridge reamer.

Having reaming problems? Our Cutting Tool Troubleshooting Guide covers reamers alongside drills and taps.