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What sizes of expansive bit are available?

What sizes of expansive bit are available?

Shop for Expansive bits

Image of an expansive bit with both large and small adjustable cutters Expansive bit sizes are governed by their cutters. Most expansive bits will be provided with two cutters, one large and one small.
Image of an expansive bit with the small adjustable cutter attached

Small cutters

Small cutters can bore holes from around 16-22mm (5/8“-7/8“) at their smallest setting to 40-50mm (19/16“-2”) at their largest.

Image of an expansive bit with the large adjustable cutter attached

Large cutters

Large cutters can bore holes from around 22-40mm (7/8“-19/16“) at their smallest setting to 76-150mm (3″-6”) at their largest.

Image to show the length of an expansive bit


Expansive bits are around 200mm (8″) long.

Image showing a stubby expansive bit compared to a standard expansive bit to illustrate the difference in the length of shank Expansive bits made specifically for plumbing, referred to as “stubby” expansive bits, have much shorter shanks and measure just 125mm (5″) in length. This allows plumbers to use the bits in confined spaces. They are now extremely rare.

A note on accuracy

Image showing that expansive bits can sometimes bore holes that are wider or narrower than intended Expansive bits have been known to cut slightly wider holes than indicated on their integrated measuring system,
Drilling a test hole with an expansive bit on a piece of scrap wood to test its accuracy This should not be a major problem but if accuracy is very important then you may need to consider boring a few test holes before you use the bit on your DIY project proper.

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