Reamers

Reamers have flutes that provide a series of cutting edges and are used to give a smoothly finished drilled holes to accurate dimensions. The shanks in hand reamers have square ends and can be turned with a tap wrench. Even though the high-speed reamers usually lasts much longer than the carbon steel type, their cutting blades lose their original keenness sooner than the carbon steel reamers.

The following are the types of reamers.

Parallel Reamer: It can only cut to one size and may have straight or spiral flutes. The straight fluted reamer is less expensive than the spiral fluted reamer. The amount of metal that can be removed by these reamers depend on their size and the type of material being used. The larger the holes, a larger the amount of metal be removed. Roughly, the amount that can be removed from 13mm diameter hole by a parallel reamer is about 0.127mm. Both types are tapered for a short distance back of the end to aid in starting.

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Expansion Reamer: This precision tool is generally used for reaming abrasive material. These reamers are built with slot cut between the flutes and a tapered screw in the head. As the reamer is used, turn the screw to expand and re-clear the reamer as it sharpens back to its original size. These reamers can be reused multiple times. This type is available in standard sized from ¼ inch to 1 inch, increasing in diameter by 1/32 inch increments.

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Adjustable Reamer: In this reamer, separate moveable blades are inserted in the grooves provided in the body of the reamer.

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Shell Reamer: It is a hollow fixed size type of reamer, which is used to ream long or deep holes such as gun barrels. It is also used on close fitting mandrels or boring bars, which pass through the hollow centre.

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Taper Reamer: It is used to prepare holes for taper pins. These reamers are available in sets numbered from 0 to 10 but the taper remains standard.

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Piloted Reamer: This user-friendly reamer ensures that it cuts centrally in the hole. The tapered end makes the reamer cut progressively ensuring a neat hole at the entry point.

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Chucking Reamer: It has shorter flutes and is used for rough cuts. They are also known as machine reamers or rose reamers or fluted reamers.

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The following are the precautions and maintenance instructions that has to be followed when using reamers.

• Handle reamer blades with care to avoid chipping them.
• Reamer blades are hardened to the point of being brittle.
• Ensure the reamer enters square in the hole.
• Turn the reamer only in clockwise direction whilst cutting and removing.
• Turn the reamer steadily and evenly to prevent scoring of the hole walls.
• Select a drill 0.003 to 0.007 inch smaller than the reamer.
• Always hand ream using the correct wrench.