Core Bits

Q: What size core bit do I need for a standard sink cutout?

Most undermount sinks call for a 1-3/8 inch to 2 inch core bit for corner radiuses, but exact sizing depends on the sink's cutout template.

Clean, precise sink cutouts start with the right diamond core bits. Basic Diamond stocks core bits for granite, marble, porcelain, and engineered stone, including segmented core bits for fast material removal and thin wall core bits for cleaner holes with less chipping. Running these on a CNC line? Our CNC tooling collection carries core bits sized to standard spindle configurations. From a single faucet hole to a full sink cutout, these bits hold up through high-volume shop use without losing accuracy.

Segmented Core Bits

Shop Now

Thin Wall Core Bits

Shop Now

Diamond Core Bits - Common Questions

What is the difference between segmented and thin wall core bits?

Segmented core bits use bonded diamond segments around the rim and cut fast, a good fit for rough openings. Thin wall core bits have a narrower kerf for cleaner edges with less chipping, which is why most shops use them on visible cutouts like sinks.

What size core bit do I need for a standard sink cutout?

Most undermount sinks call for a 1-3/8" to 2" core bit for corner radiuses, but exact sizing depends on the sink's cutout template. Check the manufacturer's diagram before drilling.

Do core bits need water, or can they be run dry?

Most diamond core bits are wet-use only. Drilling dry builds up heat that glazes the diamond segments and can crack the stone. A few dry-rated bits exist for light work, but wet drilling gives longer bit life and a cleaner hole.