DOT Core Bit Extension 12″

Description

Standard core barrels are made to drill through a normal slab or wall. The moment the penetration is deeper than the barrel is long — a thick footing, a stacked wall, a deep pier cap — the drill motor fouls the surface before the crown reaches daylight and the hole stops there.

A straightforward 12″ of reach

This extension fits between the motor and the barrel and buys 12 inches of additional depth. It is a plain, heavy steel component with matching male and female threads, which is exactly what it should be — there is nothing in a coring extension that benefits from being clever.

Using it without breaking anything

• Expect some deflection. Every inch of extension amplifies wander at the crown. Start the hole on the bare barrel, get the kerf established true, then stop and add the extension.
• Water still has to reach the crown. On a wet setup, confirm flow is coming through the extension before you commit to the cut.
• Do not stack two. Beyond about a foot of added reach the assembly loses too much rigidity to drill straight.
• Grease the joint so the barrel comes off again after a long wet drill.

A stand-mounted rig is far better than a handheld machine for extended drilling, because the stand holds the alignment the extension will otherwise lose. See core bit accessories and the wet core bit range.