Plumtool's Rapid Bore range covers three individual sizes if you don't need the full 4-piece kit — worth knowing the specs on each if you're buying just the one bit you're actually missing, rather than replacing a set.
The three sizes
The 25mm Rapid Bore bit (PTRB686, $73.56) and 32mm (PTRZ7746, $95.35) suit smaller copper and PEX runs with clearance; the 57mm bit (PTRB685, $136.21) steps up specifically to suit 50mm PVC pipe, the common DWV branch size. All three are self-clearing, built to shed timber swarf as they cut rather than packing and binding partway through a joist or stud — the main reason a wood bit burns or seizes in deep framing.
Extension bar for deep reach
The 140mm Extension Bar (PTEB537, $38.15) fits all three Rapid Bore sizes as well as 7/16in hole saw arbors, extending reach into a double joist, a thick wall plate, or anywhere the drill body can't get close enough to the timber on its own.
Buying individually vs the 4-piece kit
If you're missing one specific size — say you've already got 25mm and 32mm but need the 57mm for a DWV branch — buy that bit on its own rather than the full set. If you're starting from nothing, the Timber Rough-In Boring Kit bundles all four bits plus the extension bar at a genuine 10% saving over buying everything separately.
Frequently Asked Questions
What pipe size does the 57mm bit suit?
It's sized for 50mm PVC pipe, the common DWV branch drain diameter.
Why do some wood bits bind or smoke in deep framing?
A bit that isn't self-clearing packs with swarf as it cuts, and the friction from that packed material is what causes binding or scorching in a deep hole. The Rapid Bore range is built specifically to clear itself and avoid that.
Does the extension bar fit hole saws too?
Yes — it fits 7/16in hole saw arbors as well as the Rapid Bore bits, so it's useful beyond just timber boring.
Is it cheaper to buy one bit than the full kit?
If you only need one size, yes — buying a single bit is cheaper than the 4-piece kit. The kit's 10% saving only applies when you need the full set.