Finding a drill index set that actually cuts through hardened steel without snapping or dulling after a few holes is the difference between finishing a job in an hour and spending the whole afternoon fighting a broken bit. The market is flooded with cheap HSS sets that walk on smooth metal and lose their edge the moment you touch stainless steel, making the search for genuine cobalt content and a proper 135-degree split point the only filter that matters for serious work.
I’m Mo Maruf — the founder and writer behind The Tools Trunk. I’ve spent years analyzing cobalt steel formulations, comparing split point geometries, and stress-testing storage case durability across dozens of drill index sets to separate the true pro-grade kits from the painted tin boxes.
The 115-piece format has become the gold standard for covering fractional, letter, and number sizes in one case, but not every set delivers the M35 cobalt hardness needed for repetitive drilling in alloy steel and cast iron. This guide evaluates the best performing drill index set options available right now based on material composition, bit geometry, and real-world cutting endurance.
How To Choose The Best Drill Index Set
Not all drill index sets are built for the same materials or workloads. A set that works fine for softwood shelves will fail catastrophically on a stainless steel bracket. The three specs below define whether a set earns a spot in a serious toolbox or belongs in a weekend hobbyist’s drawer.
M35 Cobalt vs Standard HSS Steel Composition
The presence of 5% cobalt in the steel alloy is the single biggest differentiator between a drill index set that cuts through hardened metal and one that smokes and dulls on the first hole. M35 cobalt steel retains its hardness at higher temperatures generated by friction drilling in stainless steel, cast iron, and alloy steel. Standard high-speed steel (HSS) without cobalt will soften and wear rapidly under the same conditions, especially at the cutting edge where heat concentrates.
Point Geometry: 118° vs 135° Split Point
A 135-degree split point is essential for drilling into metal because it creates a self-centering action that prevents the bit from walking across the surface before engaging. The split point design also reduces the amount of downward pressure required to start the cut, which is critical when drilling into curved or uneven metal surfaces. Standard 118-degree points are adequate for wood and plastic but will skate on steel and require center punching on every hole.
Index Completeness and Case Durability
A true 115-piece drill index set should cover fractional sizes from 1/16 to 1/2 inch in 1/64 increments, plus the full A-to-Z letter set and #1-to-#60 number set. The storage case matters just as much — a metal indexed box with clear labeling keeps bits organized on the job site, while flimsy plastic trays that let bits rattle and chip edges ruin the entire system’s utility. Look for cases where each bit has a dedicated slot with visible size marking.
Quick Comparison
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| Model | Category | Best For | Key Spec | Amazon |
|---|---|---|---|---|
| KENDO 115pc Cobalt | Premium | Heavy duty metal drilling | M35 Cobalt / 5% Co | Amazon |
| YOHANSEN 115pc Cobalt | Premium | High volume production | M35 Cobalt / 135° Split | Amazon |
| BeHappy 115pc Cobalt | Mid-Range | Versatile home workshop | HS Steel / Black & Gold Oxide | Amazon |
| GuardPro 115pc Cobalt | Mid-Range | Automotive & stainless | HS Steel / 135° Split | Amazon |
| StratMet 115pc Cobalt | Budget-Friendly | Basic home repairs | M35 Cobalt / Uncoated | Amazon |
In‑Depth Reviews
1. KENDO 115 Pieces Cobalt Drill Bit Set
The KENDO set delivers genuine M35 cobalt steel with a 5% cobalt content that maintains cutting hardness even when drilling through cold rolled steel at sustained feed rates. The 135-degree split point geometry is precision ground and produces clean spiral chips without requiring excessive downforce, which reduces fatigue during repetitive production work. Users report drilling 75 holes in quarter-inch cold rolled steel per bit with no measurable performance loss, which matches the heat tolerance expected from true M35 alloy rather than standard HSS with a cobalt coating.
The 115-piece assortment covers the full range from 1/16 to 1/2 inch fractional sizes in 1/64 increments, plus the complete letter set A through Z and number set #1 through #60. The metal indexed storage case keeps each bit in a dedicated slot, though some users note the top tray for the larger bits requires careful handling to avoid misalignment during closure. The straight round shank fits all standard three-jaw chucks without slipping, and the 2-flute twist design clears chips effectively in both through-holes and deep blind bores.
Where this set pulls ahead of mid-range competitors is the consistent edge retention across the 115 bits — every bit in the set arrives sharp rather than only the fractional sizes being properly ground. The titanium finish adds an extra layer of corrosion resistance that helps when drilling into materials with abrasive dust or moisture present. For professional fabricators and serious metalworkers who need a drill index set that performs hole after hole without requiring resharpening mid-project, this is the most reliable option available right now.
What works
- Authentic M35 cobalt retains hardness through sustained metal drilling
- 135° split point prevents walking on smooth steel surfaces
- Full fractional/letter/number coverage in one indexed metal case
What doesn’t
- Top storage tray for larger bits can be finicky to seat properly
- Not ideal for hardened steel without cutting oil and slow spindle speeds
2. YOHANSEN 115Pcs Cobalt Drill Bit Set
The YOHANSEN set uses M35 high-speed steel with cobalt alloying that handles high-friction drilling environments without softening at the cutting edge. In practical testing, users drilled 63 through-holes in 1.5-inch A33 tool steel at 200 RPM with heavy hand feed and a turpentine oil mix — no spotting drill was needed, and the bits showed minimal deflection with clean burr formation at exit. The 135-degree split point does the self-centering work reliably, saving time on setups where center punching would otherwise be required on every hole.
The 115-piece configuration mirrors the standard industry format with 29 fractional sizes from 1/16 to 1/2 inch in 1/64 increments, 26 letter sizes A through Z, and 60 number sizes #1 through #60. The metal index storage box provides a secure home for each bit, though multiple users report the case can be difficult to open initially and the printed size markings on the larger bits are difficult to read due to the non-folding tray design. The straight shank fits standard chucks with no wobble, and the 2-flute geometry clears chips efficiently even in deeper holes.
This set earns its place for high-volume production scenarios where bit cost per hole matters and the ability to push through tool steel without premature dulling is non-negotiable. Some customer reviews suggest the bits may be standard HSS rather than true cobalt despite the product claims, so buyers working exclusively on stainless steel should verify performance on the first use. For general metal fab shops and construction crews who go through bits quickly, the YOHANSEN provides strong cost-per-hole economics.
What works
- Handles extended runs through tool steel without dulling
- Self-centering split point eliminates need for center punching
- Full size range coverage in a durable metal index box
What doesn’t
- Some units may be standard HSS rather than true M35 cobalt
- Case can be difficult to open and size markings are hard to read
3. BeHappy 115Pcs Cobalt Drill Bits Set
The BeHappy set combines high-speed steel with a black oxide and gold oxide finish that improves corrosion resistance and reduces friction during drilling, making it a strong mid-range contender for the home workshop. The 135-degree split point is fully ground and self-centering, which reduces walking on metal surfaces and allows clean entry without pilot holes in most soft and medium-hard materials. Users consistently report the bits arrive extremely sharp and perform well on stainless steel, cast iron, alloy steel, wood, and hard plastics when used with appropriate feed pressure.
The 115-piece count covers 29 fractional sizes from 1/16 to 1/2 inch in 1/64 increments, 26 letter sizes A through Z, and 60 number sizes #1 through #60. The metal indexed storage case keeps everything organized, though some users found the foam insert on top needed a small addition to prevent smaller bits from rattling loose during transport. The round straight shank design fits securely in all standard drill chucks, and the twist flute geometry effectively lifts metal shavings up and out of the hole to prevent binding.
Customer feedback shows this set is particularly well received by DIY users who need a large size range for varied projects but don’t want to pay premium pricing for a set they won’t use daily in production. The dual-finish oxide treatment gives these bits a visual edge over plain HSS sets, and the self-centering split point performs noticeably better than the 118-degree points found on cheaper alternatives. For the home mechanic, woodworker, or occasional metal fabricator, this set delivers the most usable versatility per dollar spent in the mid-range.
What works
- Black and gold oxide finish reduces friction and resists rust
- 135° split point eliminates walking on metal surfaces
- Complete 115-piece size range for varied project needs
What doesn’t
- Foam case insert may need adjustment to secure smaller bits
- Standard HSS lacks the heat tolerance of true M35 cobalt for sustained heavy drilling
4. GuardPro 115Pcs Cobalt Drill Bits Set
The GuardPro set is positioned as a cobalt-infused HSS option that targets the gap between economy steel bits and premium M35 alloy sets. The 135-degree split point with round straight shank provides the same self-centering anti-walk behavior found in pricier competitors, and users confirm the bits arrive sharp and cut cleanly through aluminum, mild steel, and stainless steel when lubricated. One verified review specifically noted the set excels on thick stainless steel and handles an hour of steady drilling with cutting oil before needing a break, which is respectable performance for the mid-range tier.
The 115-piece configuration includes 29 fractional sizes from 1/16 to 1/2 inch in 1/64 increments, 26 letter sizes A through Z, and 60 number sizes #1 through #60, all stored in a metal indexed case. The case provides dedicated slots for each bit, though some users mention the bits are more brittle than standard HSS and recommend avoiding sideways pressure or drops that could cause chipping. The twist flute design clears chips effectively, and the straight shank fits standard three-jaw chucks without slippage during operation.
The value proposition here depends on whether the cobalt content is sufficient for your specific material mix. Users drilling wood and aluminum found the set performed flawlessly, while those pushing into stainless steel noted that proper speed and cutting oil are mandatory to prevent edge degradation. For automotive work, metal fabrication, and general construction where material types vary throughout the day, the GuardPro set offers a balanced combination of sharpness, size range, and case durability at a mid-range price point that undercuts the premium options.
What works
- Capable of sustained drilling in thick stainless steel with oil
- 135° split point prevents walking on smooth metal surfaces
- Full 115-piece coverage with metal indexed storage
What doesn’t
- More brittle than standard HSS — avoid bending or dropping
- Requires cutting oil and slow speeds for stainless steel work
5. StratMet 115pcs Cobalt Drill Bit Set
The StratMet set claims M35 cobalt steel construction at an entry-level price point, making it the most accessible option for buyers who want cobalt hardness without committing to premium pricing. The 135-degree precision ground self-centering split point is present across all 115 bits, and the spiral flute geometry is designed for fast chip evacuation to prevent bit binding in deeper holes. Users report the bits cut through walls and metal parts without issues, and the bits maintain sharpness through multiple uses on standard home repair materials like drywall, wood, and mild steel.
The 115-piece size range provides 29 fractional sizes from 1/16 to 1/2 inch in 1/64 increments, 26 letter sizes A through Z, and 60 number sizes #1 through #60. The included storage case assigns each bit a dedicated slot for organization, though multiple customer reviews describe the case as the weakest component of the set — the plastic tray is difficult to use, bits can shift during transport, and the overall build quality feels cheap compared to the metal cases found on pricier competitors. The uncoated finish means there is no added corrosion protection, so bits stored in humid environments will need to be kept dry and lightly oiled.
This set is best suited for budget-conscious homeowners and DIY enthusiasts who need a large variety of sizes for occasional use and aren’t pushing bits through hardened alloy steel on a daily basis. The M35 cobalt material content is a genuine upgrade over standard HSS at this price tier, and the bits perform well on soft metals, wood, and plastic. If you can tolerate a mediocre storage case and don’t need a coated finish, the StratMet set delivers functional cobalt performance that punches above its price tier for basic to moderate drilling tasks.
What works
- Genuine M35 cobalt steel at an entry-level price point
- 135° split point provides self-centering on metal surfaces
- Full 115-piece size range for comprehensive project coverage
What doesn’t
- Storage case is flimsy and difficult to use for daily organization
- Uncoated finish offers no corrosion protection
Hardware & Specs Guide
M35 Cobalt Steel Alloy
The defining material spec for any drill index set aimed at metal drilling is the cobalt content percentage. M35 steel contains 5% cobalt, which allows the cutting edge to maintain hardness at elevated temperatures generated by friction drilling. Standard HSS without cobalt will begin to soften and lose edge retention when drilling at high RPM or through tough alloys like stainless steel. The cobalt also improves the overall wear resistance, meaning the bits stay sharp for more holes before requiring resharpening.
135° Split Point Geometry
The split point is a secondary grind at the tip that creates two cutting edges meeting at 135 degrees rather than the standard 118 degrees. This reduces the chisel edge width, which is the portion of the bit that pushes material aside rather than cutting it. The result is a self-centering action that prevents the bit from walking across the workpiece surface and reduces the feed pressure required to start the cut. For drilling metal, the 135° split point is a non-negotiable feature that separates functional sets from frustrating ones.
FAQ
What does M35 mean on a drill bit set?
Is a 115-piece drill set better than a 29-piece set?
Can I use cobalt drill bits in wood?
Final Thoughts: The Verdict
For most users, the drill index set winner is the KENDO 115 Piece Cobalt Set because it delivers genuine M35 cobalt hardness, a precision 135-degree split point on every bit, and the most consistent edge retention across the full 115-piece range for demanding metal drilling applications. If you want a balanced mid-range set with oxide coating for corrosion resistance and versatile material handling, grab the BeHappy 115Pcs Cobalt Set. And for budget-conscious buyers who still want M35 material quality, nothing beats the StratMet 115pcs Cobalt Set for entry-level pricing on genuine cobalt steel.