Bosch Expert SelfCut Speed Spade Bit 38mm x 152mm

The Bosch Expert SelfCut Speed is a 38mm spade bit built for professionals who drill a lot of holes in wood and want them done quickly, cleanly, and without the bit jamming up halfway through a joist. This is not the bit that came free with your drill. The 38mm diameter makes it ideal for running cable and conduit through timber framing, and at 152mm long it handles most stud and joist work without needing an extension.

The name is not just marketing — the self-feeding screw tip is the key feature here. It pulls the bit into the material under its own thread, reducing the downward force you need to apply. On a long run of joists or stud bays, that matters. Your wrists will notice the difference by lunchtime. The bosch 38mm spade bit also features a wave-shaped flute profile along the cutting edges, which clears chips out of the hole as you drill rather than letting them pack in and slow you down.

Where the Bosch Expert SelfCut Speed Earns Its Keep

The 38mm diameter is a very common size for first-fix electrical work — wide enough for a 25mm conduit to pass through with room for a draw cord, and for twin and earth or SWA to be run through timber in multiples. Plumbers will use it too, particularly for copper or plastic pipe runs where a clean, accurate hole matters.

The 1/4 inch hex shank fits directly into any standard drill driver chuck or quick-change hex chuck without needing an adapter. That means you can swap between bits fast on site, which adds up over a full day’s work. It also sits solidly in a hex quick-release chuck, with none of the wobble you sometimes get from round-shank bits in a three-jaw.

Build Quality and Material

Bosch manufacture the Expert range from high-grade steel with hardened cutting edges. Compared to budget spade bits, the geometry is more consistent and the tip holds its thread for longer before wear softens the self-feed action. It is not indestructible — hitting a nail or a knot at full speed will take the edge off anything — but for clean softwood and engineered timber it goes a long way before it needs replacing. Keep it for timber only and it will last.

Supplied as a single bit. If you are kitting out a van or stocking a workshop, check our bulk pricing options on Bosch spade bits across the full size range.