Daniel sent us this one — we're at Tier 5 of the DIY deep-inventory series, and this is where we pivot. The earlier tiers covered fasteners and anchors that stay in the wall. Now we're building the drilling and hole-making consumables inventory that makes all of that possible. He wants a practical baseline for someone doing regular household DIY in Israel — concrete, masonry, tile, drywall, metal, wood — and he wants specific quantities, not generic advice. Which bits to duplicate, which to buy singly, when a cheap kit is fine, and when poor quality will ruin your afternoon.
This is the episode where we get to talk about the thing that actually determines whether your anchor goes in straight or your wall looks like it was attacked by a badger. And Daniel's right to frame it this way — most people think about the fastener, but the hole is where the battle is won or lost.
The hole is the first draft of every project.
That's actually a perfect way to put it. So let's start with the workhorse category: general-purpose HSS drill bits. High-speed steel. These are your bits for metal, plastic, and wood — basically anything that isn't masonry or tile. A decent HSS bit with a 135-degree split point will self-centre and won't walk across your workpiece. The 118-degree points are cheaper but need a centre punch on metal.
The angle matters.
A 135-degree split point cuts faster, requires less pressure, and won't skate on smooth surfaces. It's one of those things where spending an extra few shekels per bit changes the entire experience. For a baseline inventory, I'd say a 19-piece HSS set covering 1mm to 10mm in half-millimetre steps is the right starting point. That gives you coverage for pilot holes, clearance holes, and tap drills across the most common metric sizes.
This is where I'd avoid the 30-shekel AliExpress set with bits that look like they were sharpened by a disinterested goat. The steel matters. A reputable manufacturer — Bosch, Makita, DeWalt, even the mid-tier Israeli hardware store brands — uses proper M2 HSS that holds an edge. Cheap HSS can be case-hardened on the surface only, and once you wear through that, the bit is essentially a metal lollipop stick.
I've met those bits. They're the ones that turn blue after three holes and then proceed to friction-weld themselves into the workpiece.
And that's the smell of defeat. For the general HSS kit, buy once from a known brand. You'll replace individual sizes as they dull or break, but the kit itself should last years. The sizes you'll replace most often are 3mm, 4mm, 5mm, and 6mm — these are your pilot and clearance workhorses. Keep at least two of each as spares.
That's the baseline. What about when you're drilling stainless steel or harder alloys?
That's where cobalt bits come in. These are HSS with 5 to 8 percent cobalt alloyed in, and they handle the heat and hardness that would destroy a standard bit. Stainless steel work-hardens as you drill, so if you use a dull bit or run too fast, the material gets harder at the point of contact and then you're really in trouble. Cobalt bits stay hard at higher temperatures and cut through that.
Are these a baseline item?
Only if you regularly work with stainless or hardened steel. For occasional DIY, I'd put these in the "buy when the project demands it" category. But if you're drilling stainless even once, buy the cobalt bit for that specific size rather than trying to force a standard HSS bit through. You'll save the workpiece and your sanity. A small set covering 3mm to 8mm is sensible if you do any metalwork — shelving brackets, appliance repairs, that kind of thing.
Lubrication is non-negotiable here.
Drilling stainless without cutting oil is one of those mistakes that feels fine for the first five seconds and then immediately becomes a ruined bit and a hardened divot you can't drill through. Any light oil works in a pinch, but proper cutting paste is better.
Now let's move to wood. Daniel mentioned brad-point bits.
Brad-point bits are the ones with the little spur on the tip and the outer cutting edges that score the perimeter before the centre removes material. They produce clean, splinter-free holes in timber and sheet goods — plywood, MDF, particle board. The centre point registers exactly where you want the hole, so there's no wandering. If you've ever tried to drill a precise hole in wood with a standard twist bit and watched it drift off your pencil mark, you know why these exist.
The difference between a brad-point and a standard bit in wood is the difference between a hole and a wound.
For a home inventory, I'd keep a set from 3mm to 10mm — those cover most dowel joinery, shelf pins, and hardware mounting. Sizes worth duplicating are 5mm, 6mm, and 8mm — those match common dowel diameters and confirmat screw pilots. A mid-range set from a woodworking brand is fine. You don't need carbide-tipped brad-points for occasional use; standard high-carbon steel with sharp spurs will do the job.
These run in a standard drill, no hammer mode obviously.
Standard drill or drill press. Never hammer mode on wood — that shouldn't need saying, but I've seen things.
We've both seen things. Let's get into masonry, because this is where Daniel's Israel-specific context really bites. Very hard reinforced concrete is not theoretical here.
It's the default. Israeli construction uses high-strength concrete with steel reinforcement, and it will expose a poor-quality bit in about 15 seconds. Standard masonry bits have a carbide tip brazed onto a steel shank, and the tip does the cutting through a combination of rotation and hammering action. The key variable is the carbide grade and the quality of the brazing. Cheap bits use low-grade carbide that chips or dulls immediately, and the brazing can fail, leaving the carbide tip embedded in your wall while the shank spins uselessly.
Which is a special kind of despair.
It's a unique moment of staring at a wall and questioning your life choices. For Israeli concrete, I recommend buying high-quality masonry bits from a reputable manufacturer — Bosch, Makita, Hilti if you're feeling flush, or the better Israeli industrial suppliers. The diameters you absolutely need: 6mm, 8mm, and 10mm, because those match the most common wall plugs. Keep at least two 6mm and two 8mm bits. These are your most-used sizes for shelving, curtain rods, light fixtures, cable channels — everything. The 6mm especially gets dull because it's doing the most holes, and a dull 6mm bit in hard concrete just polishes the hole instead of deepening it.
Then you push harder and overheat the bit and now you've got a glazed hole bottom that won't accept an anchor properly.
That's the cycle. So duplicates are not a luxury — they're downtime prevention. A 5mm bit is also useful for smaller plugs and piloting for 6mm anchors in particularly crumbly material. A 12mm bit covers larger anchors and conduit pass-throughs, but that's a single-piece purchase unless you're doing a lot of heavy mounting.
Now, the distinction Daniel asked about: ordinary masonry bits versus SDS-plus.
This is the single biggest upgrade most DIYers can make and don't realise is available to them. A standard masonry bit has a smooth cylindrical shank that goes into a regular drill chuck. An SDS-plus bit has a slotted shank that locks into an SDS rotary hammer's chuck mechanism. The difference isn't just the connection — it's the entire drilling system.
Explain the system difference.
A standard hammer drill uses a mechanical cam that vibrates the chuck back and forth. It's adding a light tapping action to rotation. It works for soft brick, lightweight block, and occasionally for concrete if you're patient and the concrete isn't too hard. An SDS rotary hammer uses a pneumatic piston to drive the bit forward with actual impact energy, measured in joules. The bit isn't just vibrating — it's being hammered into the material while rotating. The difference in drilling speed in hard concrete is night and day. A hole that takes 45 seconds with a hammer drill might take 8 seconds with an SDS rotary hammer.
The user experience difference?
With a hammer drill in hard concrete, you're leaning into it, the drill is screaming, progress is glacial, and your hands are absorbing vibration the whole time. With an SDS rotary hammer, you apply light pressure and the tool does the work. It's quieter in terms of perceived effort, though it's actually louder in decibels. The bit stays sharper longer because it's not being overheated by excessive friction from insufficient impact energy.
For someone doing regular DIY in Israeli concrete, an SDS rotary hammer is not overkill.
It's honestly one of the best tool investments you can make. Even a corded entry-level SDS rotary hammer from a decent brand will transform your experience. The bits themselves are more expensive per piece, but they last far longer and drill faster. For the SDS inventory, I'd keep 6mm, 8mm, and 10mm as the core sizes, again with duplicates of 6mm and 8mm. An SDS-plus bit set covering 5mm to 12mm is a solid foundation and often cheaper than buying individually.
What about when the bit hits rebar?
This is the moment that separates calm DIY from panic. When a masonry bit hits steel reinforcement, you'll feel it immediately — the sound changes, progress stops, and if you keep pushing, you'll destroy the carbide tip. Masonry bits are not designed to cut steel. The correct response is to stop, switch to a metal-cutting bit to get through the rebar, then go back to the masonry bit. Or, if possible, relocate the hole slightly. In practice, for small diameters, an SDS bit with a good carbide tip will sometimes chew through thin rebar, but it's not designed for it and you're gambling with the bit.
There's a broader principle here: when drilling should stop rather than applying more force.
You stop when the sound changes from a consistent grind to a squeal or chatter. You stop when the bit stops advancing despite moderate pressure. You stop when you see smoke or the bit tip is discoloured. Pushing harder at any of these points just converts your drill bit into a friction heater and your wall into a glazed, uncooperative surface. The fix is almost always: clear the hole, check the bit, possibly switch to a sharper bit, and let the tool do the work.
Dust removal — why does it matter?
Because the dust from drilling fills the hole and prevents the anchor from seating properly. If you don't clear it, the anchor grips the dust, not the wall. The simplest method is to run the drill bit in and out a few times while the drill is still spinning to auger out the debris, then blow out the hole — a small squeeze bulb or a can of compressed air works. For deeper holes, a quick vacuum with a narrow nozzle. It's a 10-second step that makes the difference between an anchor that holds and one that pulls out under load.
Tile and glass bits. Daniel mentioned these, and they deserve special attention because the mistake here is catastrophic.
Tile is unforgiving. The number one mistake is using hammer mode on tile. Hammer mode on a ceramic or porcelain tile will crack it instantly — maybe not a visible crack immediately, but a hairline fracture that propagates over time. Tile and glass bits are typically spear-point carbide or diamond-coated. Spear-point carbide bits look like a little arrowhead and they work by grinding rather than cutting. They're slow but effective on ceramic, porcelain, and glass.
Low speed, no hammer, very light pressure. Let the bit grind its way through. Some people use masking tape over the drilling point to prevent the bit from skating on glossy tile — that works. Others use a small diamond core bit with water cooling for larger holes. For a baseline inventory, a set of spear-point carbide bits in 4mm, 6mm, 8mm, and 10mm covers almost all tile drilling needs. These are consumable — they wear out, so having spares of the 6mm is sensible.
Multi-material bits. These claim to do everything. Are they real?
They're real in the sense that they exist and they do drill multiple materials. The Bosch Multi-Construction bit is the best-known example — it uses a carbide tip with a geometry that handles masonry, wood, metal, and tile. They're genuinely useful as a grab-and-go option when you're drilling mixed materials and don't want to switch bits constantly. The trade-off is they're not as fast as a dedicated bit in any single material. For a basic inventory, a small set of multi-material bits in common sizes is a great emergency backup. They're also excellent for mystery walls where you're not sure if you're about to hit brick, plaster, or a buried junction box.
Mystery walls — the DIY equivalent of a blind date with consequences.
Just as likely to end in disappointment. Step drill bits — these are the conical bits with stepped diameters marked along the body. They're designed for drilling clean holes in thin sheet metal, plastic, and sometimes wood up to about 3mm thickness. Each step increases the hole size progressively, so one bit replaces a whole set of individual sizes for thin materials.
These are the bits that look like a small metal Christmas tree.
That's exactly what they look like. They're brilliant for electrical panel work, sheet metal enclosures, plastic project boxes — any time you need a clean, burr-free hole in thin material. A single step bit covering 4mm to 20mm or 4mm to 32mm is a solid investment. You don't need a set — one good quality step bit from a reputable brand will handle most jobs. Cheap step bits lose their edge quickly and then tear rather than cut.
These are the ones that create that conical recess so the screw head sits flush.
A good countersink bit has multiple cutting flutes and works in wood, plastic, and soft metals. The combination countersink bits that include a pilot drill built in are particularly useful — they drill the pilot hole and the countersink in one operation. For a baseline inventory, a single adjustable countersink or a set with a few common sizes will cover most needs. Worth getting a decent one — a dull countersink chatters and leaves a faceted, ugly recess instead of a smooth cone.
Spade bits and Forstner bits — these are for larger holes in wood.
Spade bits are the flat paddle-shaped bits with a centre point. They're fast, aggressive, and produce rough holes. They're for rough carpentry — running cables through studs, drilling clearance holes where appearance doesn't matter. A set covering 10mm to 32mm is cheap and useful. Forstner bits are the premium option — they cut flat-bottomed, clean-sided holes with exceptional precision. They're for hinge mortises, dowel holes, and any application where the hole needs to be accurate and clean. A set from 15mm to 35mm covers most furniture and cabinetry work.
Forstner bits need a drill press for best results.
You can use them in a hand drill, but they require a steady hand and they'll try to walk if you're not perfectly aligned. A drill press turns them into precision instruments.
These are for cutting large-diameter holes — doorknobs, downlights, pipe pass-throughs.
Hole saws are essentially a cylindrical saw blade with teeth on the rim, mounted on an arbor with a pilot drill in the centre. The pilot drill keeps it centred while the saw cuts the perimeter. The critical thing Daniel flagged is the arbor — hole saws and arbors are not universally compatible. Different brands use different mounting systems. The most common are the standard threaded arbor with drive pins, and the quick-change systems like Bosch's or Milwaukee's. Buy your hole saws and arbors from the same manufacturer, or at least confirm compatibility.
What sizes are actually useful?
For household DIY, 20mm for cable grommets, 25mm for conduit, 35mm for European cabinet hinges, 50mm for downlights, and 65mm for doorknob latches. A kit with these sizes plus the matching arbor is the smart way to buy. Bi-metal hole saws with high-speed steel teeth on a tough steel body are the sweet spot — they cut wood, plastic, and soft metal. Carbide-grit hole saws exist for masonry and tile. Don't buy the cheapest hole saw kit — the teeth dull immediately and then you're just friction-burning circles into your workpiece.
Deburring and chamfering tools. These clean up the sharp edges after drilling.
A simple countersink-style deburring tool with a swivel head handles both the inside and outside edges of drilled holes in metal. For plastic and wood, a chamfering bit or even a light touch with a larger drill bit by hand works. A single deburring tool is sufficient for a baseline inventory — it'll last years.
Drill stops and depth-control accessories.
These are the unsung heroes of accurate drilling. A drill stop is a collar that clamps onto the bit at a set distance from the tip, so you physically can't drill deeper than intended. They're essential for shelf pin holes, dowel joinery, and any time you're drilling into a wall where you know there's a pipe or cable at a certain depth. A set of drill stop collars that fit bits from 3mm to 10mm costs almost nothing and prevents catastrophic mistakes.
The difference between drilling into a wall and drilling through a water pipe is about 15 millimetres of restraint.
A drill stop gives you that restraint. Centre drills and spotting drills — these are short, stiff bits used to create a precise starting point for a larger drill bit. In metalworking, they prevent the larger bit from wandering. For home DIY, a centre drill or two in small sizes is useful if you're doing precise metalwork, but it's not a baseline item for most people. A centre punch and a steady hand cover most situations.
Tap drill sizes — Daniel specifically asked about this.
When you're tapping threads into a hole, the hole diameter has to be slightly smaller than the thread's outer diameter, leaving enough material for the tap to cut into. The formula is roughly: tap drill diameter equals the thread diameter minus the pitch. For common metric threads: M3 uses a 2.5mm drill, M4 uses 3.3mm, M5 uses 4.2mm, M6 uses 5mm, M8 uses 6.8mm, M10 uses 8.5mm, and M12 uses 10.8mm for M8 is the one you'll use most often in DIY — it covers a huge range of bracket and hardware mounting.
8mm HSS bit is worth keeping specifically labeled for tapping.
Keep one or two 6.8mm bits separate from your general set and mark them clearly. The 5mm for M6 is also common. A small tap and die set with matching drill bits is a better buy than trying to assemble these individually.
Broken screw extractors — when do these earn their place?
If you're doing any amount of work with older fixtures, rusted screws, or you occasionally snap a screw head off, a set of screw extractors is worth having. They're essentially reverse-threaded bits that bite into a drilled hole in the broken screw and back it out. A small set covering 3mm to 8mm screw diameters will handle most household situations. They're a "better to have and not need" item — they cost very little and sit in the drawer until that one day when they save you an hour of creative cursing.
Let's talk about the common mistakes Daniel listed, because these are the things that turn a 20-minute job into a weekend repair.
Using hammer mode on tile — we covered that, but it bears repeating. It's the single most common drilling mistake and the consequences are immediate and expensive. Using a masonry bit on metal reinforcement — the carbide tip is brittle and designed for percussive crushing, not cutting. It'll chip or shatter. Running large bits too quickly — larger diameters need lower RPM. A 50mm hole saw at 3000 RPM is a recipe for burned wood, melted plastic, and a bit that's ruined before it finishes the first hole. The general rule: the larger the diameter, the slower the speed.
Drilling stainless without lubricant — we covered that. Using a blunt bit and compensating with pressure — that's the one that sneaks up on people.
Because it feels like the natural response. The bit isn't cutting, so you push harder. But pushing harder generates more heat, which dulls the bit faster, which makes you push harder. It's a death spiral. The fix is to stop, sharpen or replace the bit, and let the cutting edges do the work.
Buying an enormous set with dozens of near-duplicate sizes but no useful spares.
The classic 100-piece drill bit set for 60 shekels. You get 20 sizes of tiny bits you'll never use, one of each useful size, and the steel is so soft you can bend a 3mm bit with your fingers. You're better off with a smaller set of good bits and duplicates of the workhorse sizes.
Confusing shank size with cutting diameter — this catches people on hole saws and large bits.
The shank is the part that goes into the chuck. On many large bits, especially hole saws and some SDS bits, the shank diameter is different from the cutting diameter. A hole saw might cut a 50mm hole but have a 10mm shank. If your drill chuck only opens to 10mm, you need to check that the shank will fit. Most modern drills have a 13mm chuck, which handles most common shanks, but it's worth verifying.
Buying hole saws without compatible arbors — we covered that. And failing to check chuck capacity.
That's the one where someone buys a beautiful 16mm masonry bit and then discovers their drill has a 10mm chuck. SDS bits sidestep this entirely because they use the SDS chuck system, but for standard round-shank bits, check your drill's maximum capacity.
Let's build the inventory. Start with the compact version for occasional DIY.
For the occasional DIYer, here's what I'd put in the drawer. A 19-piece HSS twist bit set, 1mm to 10mm, from a reputable brand. One 4-to-20mm step drill bit. One countersink bit. A set of masonry bits: two 6mm, two 8mm, one 10mm, one 5mm, one 12mm. A set of spear-point tile bits: 4mm, 6mm, 8mm, 10mm. A small multi-material set for mystery walls — 4mm, 6mm, 8mm, 10mm. 8mm HSS bit for M8 tapping, labeled clearly. A set of drill stop collars. One deburring tool. That's a tight, functional kit that handles 90 percent of household drilling.
The deep inventory for frequent projects?
Add a cobalt bit set, 3mm to 8mm, for stainless and hard steel. A brad-point wood set, 3mm to 10mm, with duplicates at 5mm, 6mm, and 8mm. An SDS-plus bit set, 5mm to 12mm, with extra 6mm and 8mm bits. A hole saw kit with arbor, covering 20mm, 25mm, 35mm, 50mm, and 65mm. A spade bit set, 10mm to 32mm. A Forstner bit set, 15mm to 35mm, if you do any furniture work. A set of screw extractors. A centre drill or two for metalwork. And a cutting fluid or paste for metal drilling.
The ten items most likely to rescue a stalled job?
A sharp 6mm masonry bit, a sharp 8mm masonry bit, a 6mm multi-material bit for mystery walls, a 6.8mm HSS bit for tapping, a 4-to-20mm step drill, a set of tile bits, a 5mm HSS bit for pilot holes, a countersink bit, a drill stop collar, and a screw extractor set. Those ten things cover the moment when you're staring at a problem and the bit you need isn't in the kit.
Where to buy locally versus where AliExpress is fine?
Buy locally from a reputable manufacturer for anything that touches concrete — masonry bits, SDS bits, and tile bits. The carbide quality matters too much to gamble. Also buy HSS twist bits from a known brand locally — the steel quality is the difference between a bit that cuts and a bit that burns. AliExpress is reasonable for drill stop collars, deburring tools, screw extractors, and storage cases. These are low-precision items where material quality is less critical. Step drills from AliExpress are hit and miss — some are surprisingly good, others are butter-knife grade.
Inspection and replacement routine?
Before any significant project, check your most-used bits — the 6mm and 8mm masonry, the 5mm HSS, the step drill. Look at the cutting edges under good light. If the edge reflects light, it's dull — a sharp cutting edge doesn't catch the light. If the carbide tip on a masonry bit has chips or rounded corners, replace it. Replace HSS bits when they require noticeably more pressure to cut, or when they produce dust instead of chips in metal. For tile bits, replace when the cutting slows dramatically or the tip shows visible wear. A dull bit doesn't just work slowly — it damages workpieces and creates unsafe situations.
A dedicated drill bit case with labeled size slots is the gold standard. The key requirements: bits shouldn't touch each other — cutting edges banging together dull each other. Sizes should be clearly marked so you're not playing "which one is 6mm" by holding bits up to the light. The case should close securely so bits don't migrate between compartments. For SDS bits, a separate case or a dedicated rail works well. For hole saws, keep them with their arbor in a small dedicated box. The goal is that you can open the drawer, see immediately what you have, and grab the right bit in five seconds.
A bit without a known size is just a metal stick.
That's the inventory. The through-line here is that drilling consumables are not the place to save money at the expense of quality. A good bit costs a few shekels more and lasts ten times longer. The cheap bit fails at the worst possible moment and damages your work. Daniel's framing this as Tier 5 — the beginning of the tools and consumables phase — and it sets the tone for everything that follows.
The hole is the first draft, and you can't edit a bad hole.
You can fill it and start again, but that's a different kind of episode.
Now: Hilbert's daily fun fact.
Hilbert: In the high medieval period, scholars on São Tomé and Príncipe briefly embraced a theory that Aztec patolli scoring was determined not by the throw of beans but by the position of the moon relative to specific coastal rock formations — a model that collapsed when someone actually tried to play a game using it.
The moon was losing at patolli.
The moon always goes all-in on the first round.
One thought to leave with: the difference between a frustrating afternoon and a satisfying project often comes down to whether the right sharp bit was in the drawer when you needed it. Build the inventory before you need it. Thanks to our producer Hilbert Flumingtop. This has been My Weird Prompts. Email the show at show at my weird prompts dot com.
We'll be back with Tier 6 — cutting consumables. Stock up on bandages.
