Selecting The Proper Increment Borer

Finding the right increment borer can be a simple matter of the size and type of trees to be sampled. Bit length, thread style, and core diameter are the key features to keep in mind when choosing a borer.

The proper bit length depends on the diameter of trees to be sampled. Bit length should be equal to approximately ½ the diameter of the tree.

Increment borers are available in either two- or three-thread designs. Which design you choose depends largely on the type of trees to be sampled. Two-thread borer bits are more suitable for harder wood. They turn slower and generate more strength during a turn. This results in deeper penetration with each turn.

Three-thread borer bits grab the wood faster, and turn more easily. However, threading is not the only factor influencing the ease and speed of taking tree cores. Wood type, friction, and the capabilities of the user all help determine whether the core sample will be taken easily.

Diameter of a core is determined by the inside diameter of the thread end of the bit. The most common sizes are 4.3 mm, 5.0 mm, and 5.15 mm, depending on the manufacturer. The larger diameters are most often used for measuring the fiber length of wood and for quantitative analysis when larger samples are required.

Once the proper increment borer has been selected, a few maintenance tips will help ensure a long life for the borer. Tree sap and moisture can etch, pit, or otherwise damage the borer making it ineffective, so borers should always be cleaned prior to storage.

Use WD-40 or any light oil and a tissue or cloth to clean borer bits. If rust becomes a problem, fine steel wool may be substituted for the tissue or cloth. After cleaning, beeswax may be applied to the borer threads and shank for ease of operation and to help protect the tip. All parts should be dry prior to storage. If small nicks develop in the tip of the borer that cannot be removed with steel wool, they can often be repaired by the manufacturer.