Let me tell you about the worst sound in home renovation. It’s not the scream of a circular saw kicking back. It’s the crunch of a cheap carbide hole saw biting into a $12 porcelain tile and instantly turning it into a spiderweb of cracks.
I’ve heard that sound more times than I want to admit. I’ve watched a fully laid shower wall lose a tile because I got impatient and pushed too hard. I’ve burned through six hole saws on a single bathroom remodel and spent more on replacements than I did on the tile itself. If you’ve ever tried to drill a clean hole for a shower valve, a faucet stub-out, or a toilet flange in porcelain, you already know the pain.
Porcelain is not ceramic. It’s denser, harder, and it does not forgive mistakes. Glass is worse. Granite laughs at you. So when I saw this 18-piece diamond hole saw kit with a suction cup guide for $29.99, I had two thoughts: that’s cheap, and cheap usually means I’ll be buying another one in three weeks.
I was wrong. Mostly.
Why regular hole saws ruin your tile
Before I get into what this kit does right, let me explain the actual problem so you know why diamond matters.
A standard bi-metal or carbide hole saw doesn’t cut tile. It grinds it. The teeth grab, the heat builds, and porcelain — which is basically fired clay under insane pressure — either chips at the edge or cracks straight through the body. You can sometimes get away with it on soft ceramic backsplash tile. You will never get away with it on floor-grade porcelain.
Diamond hole saws work differently. There are no teeth. The cutting edge is a thin rim of abrasive diamond grit, usually brazed onto a steel tube. It doesn’t bite. It sands its way through. That’s the whole game, and that’s why a $6 set from the bargain bin isn’t going to work — the grit flakes off after two holes.
This kit gives you eighteen of those tubes, ranging from 6 mm up to 50 mm. That spread covers almost everything a normal person drills: faucet supply lines, shower arms, toilet bolts, drain pipes, soap dispenser holes, and the occasional Euro-style shower valve body.
The suction cup guide is the real story here
Most diamond hole saws are just a tube with a shank. You hold them with your hand, you tilt them, you pray. The bit walks across the slick tile face before it bites, and the first thirty seconds are pure anxiety.
This kit includes a double suction cup guide. It’s a plastic bracket with two rubber cups that lock onto the tile surface, and a slot in the middle that holds the hole saw at a perfect 90 degrees.
I didn’t think much of it until I used it. Then I realized it solves the single biggest cause of ruined tiles: the wandering start.
You lock the cups down, you drop the bit into the guide, you start the drill at low speed. The bit sits dead perpendicular. No tilt, no walk, no chipped edge. The cups held fine on polished porcelain and even on a textured matte floor tile. They didn’t hold as well on a rough slate-look surface, which is worth knowing. On very textured stone, the suction is weak and you’re back to freehand.
If you pick one up through the links here, I might get a small cut — doesn’t cost you extra and it helps keep the lights on.
Cutting dry vs wet — and why you should care
The listing says dry/wet. Let me translate that into what actually happens in your garage.
Dry cutting works. Especially on small holes. I drilled a dozen 8 mm holes for shelf anchors dry, no water, no problem, and the bits still cut fine afterward. But dry cutting generates heat fast, and heat kills diamond grit. On anything bigger than about 20 mm — think shower valve or drain holes — you need water. Not a flood. A trickle.
My method: a spray bottle of water, a couple squirts into the cut every ten seconds or so. The bit stays cool, the dust turns into a gray slurry instead of airborne silica (which you do not want to breathe), and the cut goes twice as fast. The guide has a small opening that lets you squirt water right at the contact point without pulling the bit out.
Here’s the thing nobody tells you about wet cutting: it’s messy. Slurry runs down the wall. Put a towel down, tape a plastic sheet, do whatever you have to. The tradeoff is a hole that looks like it was drilled at the factory.
Speed and pressure — the two mistakes everyone makes
If you buy this kit and run your drill at full speed and lean into it, you’ll kill it in one tile. That’s not a knock on the product. That’s how diamond works.
You want low RPM — somewhere around 800 to 1,500 is plenty for a corded drill on the low setting. Let the grit do the work. Pressure should feel like you’re resting your hand on the drill, not pushing. If you see sparks, you’re doing it wrong. If the bit is smoking, you’re doing it wrong. If it’s taking a while, that’s normal — a 35 mm hole through porcelain takes three to five minutes, and that’s a good cut.
I ran the 50 mm bit through a piece of 3/8 inch porcelain floor tile as a test. About six minutes, steady water, no chipping on the exit side. The hole was clean enough to seat a drain flange with no sealant gap.
Where it struggles
Let’s be honest about the weak spots, because there are a couple.
First, the shanks. They’re round, not hex. On a keyless chuck that’s fine. On a drill with a worn chuck, a round shank can slip under load. I had one slip on the 40 mm bit when I got impatient. My fault, but a hex shank would have forgiven it.
Second, the smaller bits — the 6 and 8 mm ones — are thin-walled. They cut beautifully, but they’re not going to survive being dropped on concrete or used as a pilot for a bigger bit. Treat them like the precision tools they are.
Third, the case. It’s a molded plastic tray that holds everything in labeled slots, which is genuinely useful, but the latch feels like it’ll be the first thing to break. Mine has held up for four months of regular use, so maybe I’m wrong.
Fourth, the suction cups lose grip on dusty or wet surfaces. Wipe the tile first. That’s a two-second fix, but if you skip it, you’ll be chasing the guide across the wall.
What 18 pieces actually gets you
Here’s the size breakdown, roughly, and what each range is for:
The 6-12 mm bits handle pilot holes, shelf pins, small supply lines, and glass tile. The 14-25 mm range is your faucet and shower arm territory. The 30-40 mm bits are for shower valve bodies and larger stub-outs. The 50 mm is your drain and toilet flange work.
That’s not a random spread. That’s a kit designed by someone who’s actually tiled a bathroom. I’ve used maybe nine of the eighteen bits so far, and every one I’ve reached for has been the right size for the job. That’s rare in cheap multi-piece sets, which usually pad the count with junk sizes you’ll never touch.
While I was laying out the shower wall, it reminded me of the quirks I ran into with the 5Pcs/Box 4 in Diamond Saw Blade, Super Thin Porcelain Blade — same lesson, different tool: let the diamond cut, don’t force it. If you’re doing a full tile job, not just drilling holes, that blade is the other half of the equation.
And if you’re cutting full 600 mm floor tiles for the same project, the 24 inch Double Guide Rails Manual Tile Cutting Machine Wide Aluminum Bottom Plate Ceramic Porcelain Floor Tile Cutter Heavy Duty 600mm/60cm R2818T060 is worth a look — you don’t want to be freehanding those with an angle grinder.
The price math nobody talks about
Eighteen diamond bits for thirty bucks works out to about $1.66 per bit. A single branded diamond hole saw at the big box store runs $15 to $30 for one size.
Now, these are not pro-grade bits. A $40 diamond core bit from a tile supply house will outlast this entire kit. If you drill tile every day for a living, buy the pro bits. But if you’re a homeowner doing one or two bathrooms, or a contractor who needs a full range on the truck without dropping $500, this is a stupid-good value.
The 4.2 star rating out of 391 reviews tracks with my experience. Most of the complaints I’ve seen are from people running the drill too fast or too dry — which is user error, not a product defect. The rest are about the suction cups, which is fair.
Who this is actually for
If you’re drilling one hole in a ceramic backsplash, you can get away with a cheap $8 bit and a lot of patience. But if you’re doing a bathroom remodel, running new plumbing, or working with porcelain or glass, this kit pays for itself the first time it saves a tile.
Given that a single cracked floor tile can mean tearing up a section of the floor to replace it, the $29.99 is basically insurance. That’s the honest reason I keep it in the truck.
One tip before you buy: get a spray bottle and a diamond-grit dressing stone at the same time. A few passes on the dressing stone when a bit starts feeling slow brings the edge back. I’ve revived bits three or four times this way, and they’re still cutting.
The kit isn’t perfect. It’s not pro-grade. But it does the job, it does it clean, and it costs less than the tile you’d waste learning the hard way.
Check the current price on the 18 PCS Diamond Hole Saw Kit here.