Bosch Impact Tough Titanium Nitride Coated Drill Bit Set

Why I reached for these bits

I reach for an impact driver more than I probably should. Fasteners are its bread and butter, but every so often I need to pop a hole without swapping over to a drill/driver. That’s what drew me to the Bosch Impact Tough set: titanium nitride–coated bits that claim to hold up to the hammering of an impact driver while covering the bread‑and‑butter sizes I use most. I spent several weeks using the 9‑piece variant and borrowed the 5‑piece to see how it compares. I ran them in an impact driver and a standard drill/driver across wood, composite sheet goods, plastics, aluminum, and mild steel.

What you get and how they’re built

The simplified lineup is straightforward. The 5‑piece set includes 3/32", 1/8", 5/32", 3/16", and 1/4". The 9‑piece adds 1/16", 7/32", 5/16", and 3/8". All are coated in titanium nitride (TiN) and, importantly, are designed to be used with impact drivers. In practice that means a 1/4" hex shank and a more robust construction than standard round‑shank HSS bits.

The TiN coating is there for wear resistance and heat management. It’s not magic armor; once you overheat the cutting edges, they dull like any HSS bit. But a quality coating does reduce friction and extend edge life in the materials these bits are meant for.

The hex shank is the unsung hero. Quick‑change swaps are faster, and in an impact driver the bit won’t spin in the chuck under load. If you move back and forth between drilling and driving screws on a trim job or a cabinet install, that convenience matters.

Setup and compatibility

I used these primarily in a 1/4" impact driver at low to medium speed for metal, and high speed for wood and plastics. I also ran them in a drill/driver when I wanted more control and a clean start. The bits fit every quick‑change chuck I tried, and I didn’t see any wobble beyond what you’d expect from hex‑shank bits.

A quick note on technique: impact drivers can “pulse” the bit, which isn’t always ideal for drilling clean holes—especially in metal. The bits will tolerate it, but you’ll get smoother results in tougher materials with a drill/driver set to drill mode. I treated the impact driver as a convenience tool here, not the only way to run these bits.

Performance in wood and sheet goods

In pine, poplar, and construction lumber, the Bosch set is thoroughly competent. The smaller sizes tracked straight with light pressure. The mid‑range (5/32" to 1/4") cleared chips well in both softwood and hardwood, and I didn’t get much “walking” when starting on a flat surface. In plywood and MDF, hole walls were clean and tear‑out was minimal when I backed out periodically to clear chips. The 3/8" bit, spun fast in a drill/driver, made neat holes without chattering.

Plastics (ABS and PVC) were similarly drama‑free. Run the bits at a moderate speed, don’t bear down, and they won’t melt or grab. If you’re a carpenter or DIYer drilling occasional pilot holes, hinge cups for small hardware, or clearances for cable runs, these bits do exactly what you’d expect.

Performance in non‑ferrous metals

Aluminum angle and thin sheet (up to 1/8") were fine. With a little cutting fluid and low RPM, the 1/8", 3/16", and 1/4" sizes cut predictably. The TiN coating helped keep the edges from galling, and the hex shank prevented any slipping under load. I prefer a drill/driver for these holes—the smooth torque makes a nicer start—but the impact driver handled them when convenience won out.

Brass sheet behaved similarly: slow speed, light pressure, steady chips, no problem. Deburr the exit side and you’re done.

Performance in steel

Here’s where expectations matter. In mild steel sheet (up to about 16‑gauge) and very light angle, the smaller sizes were workable if I punched a clear starting dimple, kept speed low, and used cutting oil. The 1/8" bit made a handful of clean holes before I noticed the edges softening. By the time I stepped up to 3/16" in 1/8" angle iron, progress slowed and the bit wanted more pressure than I like to apply. The 1/4" and larger sizes got hot quickly if I wasn’t meticulous about speed and lubrication.

In thicker mild steel and anything hardened or stainless, these bits are simply out of their depth. Even with oil, low RPM, and peck drilling to clear chips, I saw edge wear arrive fast. That’s not a knock unique to this set; TiN‑coated HSS bits in general aren’t the right choice for regular steel work. If your week includes a lot of steel or stainless, step up to cobalt (M35/M42) or carbide where appropriate, and use a drill/driver or drill press.

Durability and edge life

In wood and plastics, edge life was good. After a few dozen holes across common sizes, the cutting edges still felt sharp by fingertip and produced clean shavings. The TiN coating showed the usual polishing on the lands but stayed intact.

In aluminum, edge life was decent so long as I kept the speed down and cleared chips. Pushing the pace dulled the smaller sizes more quickly but still within what I’d call normal wear.

Steel accelerated wear the most. After a small run of holes in mild angle iron with the 3/16", I noticed clear dulling and slower cut rates. The takeaway: these bits are durable in the materials they’re aimed at, but steel will shorten their life in a hurry.

On the shank side, no twisting or rounding over. The hex interfaces stayed crisp, and I didn’t snap any bits under impact driving. That’s encouraging for anyone who’s broken daintier twist bits trying to run them off an impact.

Size coverage and selection

The 5‑piece kit covers the pilots and small clearances most carpenters and installers need: 3/32", 1/8", 5/32", 3/16", 1/4". The 9‑piece fills the common gaps and tops out at 3/8" with 1/16", 7/32", 5/16", and 3/8". For cabinet hardware, pocket‑hole work, anchors, and general shop tasks, the 9‑piece has been the more practical choice in my bag.

If you frequently need sizes larger than 3/8" or specialty points, this isn’t that set. But for day‑to‑day jobs, the coverage makes sense.

Value and who it’s for

The value proposition is tied to convenience and general‑purpose drilling. If you live on an impact driver and want quick‑change bits that won’t twist in the chuck, this set earns its keep. For carpentry, light electrical and plumbing work, and shop tasks in wood and non‑ferrous materials, you’ll get good performance per dollar.

If your work includes repeated drilling in steel—especially thicker or stainless stock—the value falls off quickly. You’ll spend the savings replacing dulled bits and wishing for a cobalt set.

Tips for best results

• Use a drill/driver for metal when possible; save the impact driver for convenience and tight spaces.
• Center‑punch steel and aluminum to prevent walking, especially with larger sizes.
• Run low RPM and use cutting oil on metals; peck drill to clear chips and keep heat down.
• In wood and plastics, higher RPM and light pressure give cleaner holes and longer edge life.
• Step up through sizes for larger holes instead of jumping straight to 5/16" or 3/8".

The bottom line

The Bosch Impact Tough set slots neatly into the “do most things well” category for impact‑ready drill bits. In wood, sheet goods, plastics, and non‑ferrous metals, they’re easy to live with: quick changes, predictable cutting, and edge life that matches the promise of the TiN coating. In steel, their limitations show up quickly. Treat them as generalists, not metalworking specialists, and you’ll be satisfied.

Recommendation: I recommend this set for carpenters, installers, and DIYers who want impact‑driver convenience and solid performance in wood, plastics, and light metals. If your workload includes regular drilling in steel or stainless, skip these and invest in cobalt or carbide bits designed for that job.