Core Bit Tube Extensions

World Diamond Source® engineers heavy-duty Core Bit Tube Extensions to effortlessly expand your drilling depth beyond standard barrel limits. Precisely machined from high-tensile steel, these premium extensions are built to withstand extreme industrial torque while maintaining perfect concentric alignment to eliminate bit wobble or vibration. Designed to integrate seamlessly with our signature removable cap design, they install quickly between the barrel and the cap assembly to ensure deep-hole penetration through hard concrete with reinforcement. Available in multiple lengths and standard industry thread sizes—including 5/8″-11 and 1-1/4″-7 connections—our deeply stocked inventory ensures your crew has the exact extension needed with zero lead-time delays.

Frequently Asked Questions

What does a core bit tube extension do?

It sits between your drill and the core bit to add drilling depth past the barrel's own length, so you can go through a thick slab or wall without buying a longer bit. Each extension is machined from high-tensile steel to hold concentric alignment, because a poorly made extension is what causes bit wobble and a bell-mouthed hole.

What lengths do you stock?

1", 1-1/8", 1-1/4", 1-1/2", 2", 2-1/2", 3", 3-1/2", 4", 4-1/4", 4-1/2", 5" and 6". The short lengths are for fine-tuning depth; combine or step up in length when you need more reach.

Can I stack more than one extension?

You can, but every joint you add is another place for runout to build up, and the longer the stack the more the bit will want to wander and the harder the rig has to work. Use the single longest extension that gets you the depth you need rather than a chain of short ones, and keep the rig anchored solidly.

Will an extension fit my core bit and my drill?

Extensions are made to thread between the machine and the barrel, and thread sizes vary by rig and bit. We also stock a range of core bit adapters and accessories for bridging between different connections. Give us your drill's make and model and the thread on your bits and we will confirm exactly which extension and adapter you need.

Do I need to change how I drill when using an extension?

Yes, ease off. The extra length means more deflection and less rigidity, so use lighter feed pressure, let the bit find its own rate, and make sure water is still reaching the crown at the bottom of a deep hole. Do not let the bit stall in the cut with an extension fitted.

Not sure which tool fits your machine? Call 800-611-8278 and we will confirm before you order.