117mm Drill Bits

When you need to bore very large apertures through exterior walls, our professional range of 117mm drill bits provides the heavy-duty performance required. 117mm is a highly specific, standard diameter used by plumbers, heating engineers, and electricians for running 100mm (4-inch) extractor fan ducting, soil pipes, and boiler flues through solid masonry. Cutting a hole of this size requires specialist accessories engineered to handle extreme friction and torque.

We supply a focused selection of 117mm dry diamond core drill bits designed specifically for cutting clean, precise holes through brick, blockwork, and concrete without causing excessive spalling or damage to the surrounding wall. Unlike standard masonry bits, core drills only cut the outer circumference of the hole to remove a solid material plug, making the process faster and significantly reducing the strain on your power tool. Look for slotted barrel designs that ensure rapid dust extraction and keep the cutting edge cool during prolonged use. Ensure professional, trade-quality results with robust core bits from leading brands like Bosch and Mexco.

Frequently Asked Questions | FAQs

What is a 117mm core drill bit used for?

A 117mm core drill bit is widely used by the trade to cut perfectly sized circular holes through masonry walls for 100mm (4-inch) extractor fan ducting, plastic soil and vent pipes, and standard boiler flues. The extra 17mm of clearance allows the 100mm pipe or duct to slide through the wall easily while leaving enough room for insulation or sealant.

Do I need a special drill for a 117mm core bit?

Yes. Drilling a 117mm hole requires a highly powerful, dedicated diamond core drill or a heavy-duty rotary hammer drill (which must be used strictly in rotary-only mode). A standard 18V combi drill does not have the necessary torque to drive a bit this large, and attempting to do so will likely burn out the motor. Crucially, any drill you use for a 117mm core bit must have a mechanical or electronic safety clutch; if the bit catches or jams in the brickwork, the clutch will disengage the drive to prevent the drill from violently spinning and causing serious injury.

Should I use hammer action with a 117mm diamond core bit?

No, you must never use the hammer action setting when using a diamond core drill bit. The hammering impact will shatter the diamond segments on the cutting edge, immediately ruining the bit. Diamond core bits are designed to cut cleanly through friction and abrasion using smooth rotary action only.