Milwaukee Cobalt Red Helix Drill Bit

Eleven fractional sizes, from 3/32 inch up through 1/2 inch: 3/32, 7/64, 1/8, 9/64, 5/32, 3/16, 1/4, 5/16, 3/8, 7/16 and 1/2 inch. Each size is its own Milwaukee part number, running 48-89-2303 for the 3/32 through 48-89-2329 for the 1/2 inch, so order by the size you need rather than by the series alone.

Yes. The Red Helix bits are cobalt alloy and Milwaukee rates them for hard metals, and also for PVC and wood. The cobalt alloy is what buys the life in hard material, up to 15 times the life of a black oxide bit.

No. The Cobalt Red Helix bits are built for hard metals, PVC and wood, with a 135-degree split point and cobalt alloy body for metal cutting. For concrete or block you want a carbide-tipped rotary/percussion bit such as the Minerallac 59736 Relton 1/2 inch x 6 inch carbide-tipped rotary/percussion bit, which is made to be run in hammer mode. Running a cobalt twist bit in a hammer drill on masonry will destroy the cutting edges.

Use a diamond grit bit rather than a twist bit. The Lenox 12111-10DGHS is a 5/8 inch diamond grit drill bit in the D/S-10Dg series, which abrades hard, brittle material instead of cutting a chip. The Milwaukee Cobalt Red Helix bits use a QUADEDGE tip and variable helix flute to evacuate chips from metal, PVC and wood, which is a cutting action tile does not respond to.

Yes, two. For the steel, the Milwaukee Cobalt Red Helix in 1/2 inch is part number 48-89-2329, a cobalt alloy bit for hard metals. For the slab, a carbide-tipped rotary/percussion bit like the Minerallac 59736 Relton 1/2 inch x 6 inch covers the same hole diameter in concrete and gives you 6 inches of length for slab depth.

The shank has a 3-Flat Secure-Grip, three flats ground on the shank so the chuck jaws bite instead of letting the bit spin. That is the detail that matters if you are running a cordless drill into metal at higher torque. It works in a standard three-jaw chuck, keyed or keyless.

The tip is a 135-degree split point, which self-centers and starts cutting immediately rather than skating across the surface, so you can start without punching in most cases. On a curved or slick surface a punch mark is still the safer move.

For repeat holes in steel strut, panel backs and enclosures, yes. Cobalt alloy is rated up to 15 times the life of a black oxide bit in that duty, and the enhanced tapered web thickens the core so the smaller diameters resist snapping. If your work is mostly wood and plastic, black oxide is the cheaper consumable.

Yes, each diameter is stocked individually under its own Milwaukee number, so you can replace just the size you burn through most. The small diameters that break first, 3/32 (48-89-2303), 7/64 (48-89-2304) and 1/8 (48-89-2305), are all orderable on their own.

They are not interchangeable in that direction. The Minerallac 59736 Relton bit is a carbide-tipped rotary/percussion design, meaning it is intended to be struck by a hammer mechanism, not run as a twist bit in a drill chuck for clean metal holes. The Milwaukee Cobalt Red Helix bits are the metal-cutting option, with a 3-flat Secure-Grip shank that resists spinning in the chuck and an enhanced tapered web strengthening the core, and cobalt alloy rated for up to 15 times the life of black oxide bits.

Use the cobalt twist bit for that work. The Milwaukee Cobalt Red Helix range starts at 3/32 inch, part number 48-89-2303, and steps up through 7/64, 1/8, 9/64, 5/32 and 3/16 inch before reaching the larger fractional sizes. The comparable Lenox 12111-10DGHS diamond grit bit and the Minerallac 59736 Relton carbide-tipped bit are both 1/2 inch and larger, so neither covers small pilot-hole diameters.

Two features address heat: the QUADEDGE tip is built to cut faster with less heat build-up, and the variable helix flute clears chips quickly so swarf is not packed in the hole generating friction. On thick or hard stock, cutting fluid and a slower RPM still extend the bit's life.