Holes a twist bit cannot make
A twist bit makes a 10 mm hole. These make the ones you actually need.
Every cable gland, every panel grommet, every lock barrel and every conduit entry wants a round hole somewhere between 16 and 30 mm. Twist bits do not go there, and a step drill walks on thin steel. A toothed cutter with a pilot bit through the middle does: the pilot finds the centre punch and holds it, and the ring of teeth takes out the rest.
Read this first: the maker publishes no hardness, no speed and no thickness limit.
For a metal cutter those are the three numbers that matter, and this maker gives none of them. No HRC hardness, no recommended RPM per size, and no maximum material thickness. We are not going to invent them. Its own spec sheet says one thing about the steel — “High Speed Steel” — and no grade behind it, so treat these as uncoated HSS: not bi-metal, not cobalt, not carbide.
On the 68 mm figure. That is the overall length of the assembled cutter, pilot bit and shank. It is not cutting depth. The maker does not publish cutting depth, so do not plan a deep cut around it.
What that makes them good for. Sheet and plate you can get a pilot through, aluminium, plastic, plywood and board. Slow speed, steady pressure, and cutting fluid on steel. They are workshop cutters, not a replacement for a mag drill on structural steel.
16 – 30 mm
Five sizes: 16, 18.5, 20, 25 and 30 mm
Pilot and arbor on each
Not a set of cups waiting for a mandrel
Ejector spring
Pushes the slug out instead of trapping it
Or take both
Uncoated and coated together — ten cutters
What you get
Five sizes, and every one of them is a complete cutter
Sixteen, eighteen and a half, twenty, twenty-five, thirty
The five diameters that cover nearly every round hole in a panel: cable glands, grommets, switch bodies, conduit entries, lock barrels.
All five are the same overall length, 68 mm assembled, so swapping sizes does not change how far the cutter stands out of the chuck.
Each one arrives complete, not as a cup
Cutter blade, arbor, centre pilot drill, ejector spring, grub screw and its own hex key. The pilot finds your centre punch and holds the cutter there while the teeth start; the spring pushes the slug back out when you are through.
Five assemblies, five hex keys — so there is always one in the drawer when the grub screw needs a nip.
Uncoated, coated, or one set of each
Same five sizes either way, same accessories, same hex keys. The gold set carries a titanium coating; the silver one is bare high-speed steel.
The maker puts no number on how much the coating buys you, so neither do we. The honest rule of thumb: coated if you cut steel often, uncoated if it is mostly aluminium, plastic and board.
Materials
What it cuts
The maker names steel, stainless, aluminium, plastic and wood. Here is the same list with the part it leaves out — how thin, and what to do differently.
Steel sheet
The job it is built for — panels, boxes, trunking
Stainless
Slow, firm pressure and cutting fluid, or it work-hardens
Aluminium, copper, brass
Softer than steel; keep the chips clear
Tube and pipe
Clamp it — a round section spins the moment it bites
PVC and plastic
Let the teeth cut; pushing melts the edge
Plywood and board
Clean on the top face, backing board under the exit
What it will not cut. Hardened or case-hardened steel, spring steel, anything heat-treated — a plain HSS tooth is not harder than those and will round off on the first hole. Nor masonry, tile or glass. And nothing thick: this is a shallow cup with a pilot, not a mag-drill cutter, and the maker publishes no thickness limit for it.
Specification
Straight answers
Every figure here is the maker’s own. Where it publishes nothing, we say so instead of filling the gap.
Sizes
Five cutters: 16 mm (0.62 in), 18.5 mm (0.72 in), 20 mm (0.78 in), 25 mm (0.98 in) and 30 mm (1.18 in)
Overall length
68 mm (2.67 in) for every size, assembled. This is length, not cutting depth — the maker does not publish cutting depth
Steel
High-speed steel. The maker gives no grade, so we quote none. Not bi-metal, not cobalt, not carbide
Finish
Two finishes, three ways to buy: uncoated HSS (silver), titanium-coated (gold), or one set of each. The maker publishes no figure for how much longer the coating lasts, so we do not claim one
What one cutter is
Cutter blade, arbor, centre pilot drill, ejector spring, grub screw and hex key. Five complete assemblies, five hex keys
If you take both
Two complete sets — ten cutters, ten pilot drills, ten arbors and ten hex keys. The supplier does not sell it as a bundle, so it is both sets ordered together and may arrive as two parcels
Shank
Round shank with a flat, held by the grub screw. Fits a standard three-jaw chuck
Materials
The maker names steel, stainless, aluminium, plastic and wood. Copper and brass are softer than those steels, so they cut the same way. Tube and pipe work too, as long as you can clamp it
Not published
Hardness (HRC), recommended RPM and maximum material thickness. The maker gives none of the three. For a metal cutter those are the numbers that matter, and we will not make them up
Not included
Cutting fluid, and the drill in the photographs
Questions people ask
Before you order
What do I get if I pick both?
Two complete sets — one uncoated and one titanium-coated — so ten cutters, ten pilot drills, ten arbors and ten hex keys. The supplier does not sell it as a bundle, so it is simply both sets ordered together and it may arrive as two parcels. It is priced below the two bought separately — the saving is the difference against the crossed-out price above.
What is the difference between the two finishes?
The silver set is bare high-speed steel. The gold set is the same cutter with a titanium coating, which in general runs a little cooler and holds an edge longer. This maker publishes no figure for it, so we are not going to tell you it lasts three times as long. If you want the usual answer: coated is worth it if you cut steel often, uncoated is fine for aluminium, plastic and wood.
How thick a material will they go through?
The maker does not say, and we are not going to guess on a cutting tool. What we can tell you is what it is: an uncoated HSS cup with a pilot. That is a sheet-and-plate tool — electrical boxes, panels, trunking, conduit plates, plywood and board. If you are drilling structural steel, buy a bi-metal or carbide cutter from a brand that prints the number.
Do I need a separate arbor?
No. Each of the five arrives as a complete assembly — cutter, arbor, pilot drill, ejector spring and grub screw — and there is a hex key for each one. You are not buying a set of cups that then needs a mandrel.
What is the spring for?
It pushes the slug out. Without it the disc you have just cut sits inside the cup and you spend the next minute poking it out with a screwdriver.
What speed should I run them at?
The maker gives no RPM. General practice for HSS is slow and steady — the bigger the cutter, the slower — with firm pressure and cutting fluid on steel. Running one fast and dry is the usual way to ruin the teeth on the first hole.
Will they cut stainless?
The maker lists stainless among the materials. Uncoated HSS on stainless is hard work: slow speed, real pressure, and fluid, or it work-hardens and stops cutting. The coated set is the better pick if stainless is why you are buying.
Will it go through tube or pipe?
Yes, and it is one of the jobs these are good at — a cable entry into a square post, a drain in a tube. Two things change: clamp the tube, because a round section wants to spin the moment the teeth bite, and expect the cutter to grab as it breaks through the far wall. Go slower than you would on flat sheet.
Can I use them in a hand drill?
Yes, and that is what the photographs show. A corded drill or a decent cordless on its lowest speed. Hold it square — the pilot keeps it centred but it will not keep it straight for you.
Are the pilot bits replaceable?
Yes. The pilot sits in the arbor and is held by the grub screw, which is what the hex key is for. The pilot is the part that usually gives up first.
Shipping & returns
Delivery in 7–15 business days from the time you order — that window already includes the 1–2 business days we take to process. Tracking is emailed as soon as the carrier scans the parcel. Shipping & Delivery.
30-day returns. Items must be unused and in their original packaging. Email support@nexuratool.com to start a return.
Nexura Tools
Tools for repair, maintenance and the jobs in between — chosen for specs we can verify.
