How to Use an Adjustable Reamer

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Things You'll Need

  • Adjustable reamer

  • Adjustable wrench

  • Micrometer

  • T-handle tool grip

  • Thread-cutting oil

An adjustable reamer is a tool used to smooth the bore walls of a drilled hole when precise sizing is necessary. Capable of sizing holes over a limited range, each adjustable reamer has different dimension parameters. An advantage in using an adjustable reamer is that a solid reamer cannot be sharpened without reducing its diameter. The blades of the adjustable reamer can be expanded and replaced when worn. Anyone with basic mechanical knowledge can use adjustable reamers.


Step 1

Select the appropriate-size reamer in the range needed for the work to be completed.

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Step 2

Loosen the size adjustment nut on either end of the reamer, using the adjustable wrench.

Step 3

Turn the adjustment nut on one end of the reamer clockwise and the other nut counterclockwise to set the blades to the desired size. The reamer shaft is tapered and, depending on which direction the nuts are turned, the diameter of the blades increases or decreases.

Step 4

Measure the cross section of the reamer blades with the micrometer to ensure you have set the proper size.

Step 5

Tighten the adjustment nuts so they are firmly against the collars that secure the blades. Do not overtighten. Recheck the reamer blades with the micrometer for the correct sizing after tightening.


Step 6

Attach the T-handle tool grip to the square end of the adjustable reamer. Twist the movable end to the correct size and tighten.

Step 7

Apply thread-cutting oil to the blades of the reamer and around the mouth of the drilled hole.


Step 8

Align the reamer over the hole and turn it clockwise. Turn only in one direction. Oil the reamer every few turns. Thin cuts are best, with an incremental graduating of the reamer blade's diameter, until the required hole size is satisfactory.


Make sure that the work to be reamed is held securely.

Adjustable reamers have square-drive ends for T-handles, tapered ends for braces, and round shanks for use with electric drills and other machine equipment.

Replace adjustable reamer blades only as a matched set.


Always wear eye protection when using reamers.


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