“Gundrilling vs deep hole drilling” is a search phrase that comes from a confusion — and the honest answer is that gundrilling is one specific deep hole drilling method. This page explains the terms so the next search is the right one.
Gundrilling is a deep hole drilling method. “Deep hole drilling” is the umbrella term for every technique that makes holes past the twist-drill limit — gundrilling, BTA, and ejector drilling being the three core ones. So “gundrilling vs deep hole drilling” is like asking “van vs vehicle”: gundrilling is one kind of vehicle.
Gundrilling uses a single-lip drill with an external V-shaped groove. High-pressure coolant travels through the drill to the cutting edge; chips return along the V-flute. The drill is self-piloting via guide pads and needs a pilot hole or bushing to start.
| Method | Diameter | How chips leave | Best at |
|---|---|---|---|
| Gundrilling | Ø0.5–50 mm | External V-flute | Small bores, finish, straightness |
| BTA / STS | Ø6–2000 mm | Through the tube center | High metal removal, larger bores |
| Ejector / DTS | Ø18–250 mm | Venturi, double-tube | Lathe retrofits, no face seal |
Gundrilling is usually the answer.
BTA wins on feed rate.
Ejector drilling retrofits.
The interactive Method Selection Wizard works it out for you.