1. Bosch 10-Piece INOX Cutting Discs — the everyday cut
This is the pack that stays on the grinder most of the time. A cutting disc is a thin bonded wheel — abrasive grit held together with resin — and at 1mm thick it slices through steel rod, bolts, angle iron and mesh with a narrow, fast cut instead of grinding its way through. Ten in a resealable tin means you’re not paying single-disc prices every time one wears down, and they do wear down — that’s normal for a consumable.
These are the INOX grade, the iron-free version made for stainless and steel. Iron-free matters on stainless: a disc that sheds iron particles leaves specks that rust later and stain the surface, so an INOX disc keeps a clean, mark-free cut. Joel reaches for these for almost anything metal in the shed. Matt’s one note is that a thin disc is for cutting and cutting only — lay it flat to grind an edge and it can snatch or shatter, which is the flap disc’s job below. For slicing metal, on the standard 22.23mm bore so it drops onto any 125mm grinder, this is the one to buy first.
2. TOPEX Zirconia Flap Disc 10-Pack — grinding and finishing
Where a cutting disc slices, a flap disc grinds and smooths. It’s built from overlapping flaps of abrasive cloth arranged like a fan around the disc, so instead of one hard grinding face you get a cushioned surface that renews itself — as the top flaps wear away, fresh grit underneath keeps working. That makes it the disc for knocking back a weld, stripping rust or old paint, deburring a cut edge — smoothing the sharp burr off a fresh cut — or blending a repair flush.
These are zirconia — zirconia alumina is a tougher, sharper grit than the cheap aluminium-oxide flaps, so it lasts longer on steel before the grit dulls and stops cutting. Ten in a pack is the value play: flap discs are consumables like everything here, and buying them by the boxful beats paying single-disc money mid-job. The catch is that a pack is a single grit, so it sets you up for one job: coarse stock removal, or fine finishing. Matt keeps a coarse pack for heavy stock removal; Joel points out that most DIY finishing lands in the middle and one medium grit does the lot. Either way it grinds and finishes — it won’t give you the clean parting cut the thin disc does, so keep the cutter on hand for that.
3. Bosch Multi-Material Diamond Disc — for concrete and masonry
The cutting and flap discs above are made for metal. Point a bonded metal disc at concrete or a paver and it wears to nothing before the cut’s done. (Cutting concrete or masonry also throws crystalline silica — wear a P2 mask for it.) A diamond disc is a steel blade with industrial diamond grit bonded to its rim, and that rim grinds through hard, brittle materials that would eat a bonded disc: concrete, brick, pavers and cement sheet.
It’s sold as a single disc, and it costs more per unit, but a diamond disc outlasts a stack of bonded ones on masonry — the diamond edge keeps cutting long after abrasive grit would have worn away. This one has a multi-material rim rated for concrete and masonry, so it’s the do-most option for a DIYer who cuts the odd tile or trims a paver more than a tiler after a dedicated porcelain blade. Matt would add a proper tile blade if you’re doing a whole bathroom; Joel’s take is that for the occasional hard-material cut, one multi-material disc in the drawer saves buying three specialised ones. Cutting masonry throws a lot of fine dust, far more than metal, so this is the disc you never run without a mask and eye protection. It fits the same 22.23mm bore as the others.
Bore, size and the X-LOCK catch
The thing that trips people up buying discs is fitment, and it comes down to two numbers and one catch. First, disc size: 115mm and 125mm (4.5” and 5”) are the common DIY grinder sizes, and a 125mm disc needs a 125mm grinder — never fit a disc larger than the grinder and guard are rated for. All three here are 125mm.
Second, the bore — the centre hole that sits on the grinder’s spindle. The standard is 22.23mm (you’ll see it written 22.2mm or 7/8”), and every disc here uses it, so they seat on any standard 115mm or 125mm grinder with the normal flange and nut.
The catch is X-LOCK. That’s Bosch’s own keyhole-shaped mount — the disc clicks straight on with no spanner, but it only fits X-LOCK grinders, and a standard 22.23mm disc won’t lock into an X-LOCK tool either. If your grinder has a plain threaded spindle and a two-pin flange nut, you want standard-bore discs like these three; if it’s an X-LOCK tool, buy X-LOCK discs. Not sure which your grinder takes, or still shopping for the grinder itself? Our angle grinder guide and DIY grinder comparison sort that out.
Don’t go looking for a warranty on any of these. An abrasive or diamond disc is a wear item, priced and sold to be used up, so a guarantee on one makes about as much sense as one on a drill bit. The exception is a dud out of the box: a disc that turns up cracked, or flies apart on its first pass, hasn’t given fair wear at all. That’s a fault, and the ACCC’s guidance on consumer guarantees sets out when a faulty product may entitle you to a repair, replacement or refund — so hang on to the receipt. Whatever you fit, keep the guard on: a disc letting go at full speed is the whole reason it’s bolted there.
The verdict
You’re cutting metal, which is most shed jobs: the Bosch INOX 10-pack. Thin, fast and clean on steel and stainless, and cheap enough per disc that wearing them out doesn’t sting — the one to buy first.
You’re grinding back welds, rust or rough edges: the TOPEX zirconia flap pack. It smooths and blends where a cutting disc can’t, and the ten-pack means you’re not rationing them mid-job.
You’re cutting concrete, brick or pavers: the Bosch multi-material diamond disc. The only one here that touches masonry, and it outlasts a pile of bonded discs doing it.
Most sheds want the first two on the shelf and the diamond disc in the drawer for when a hard-material job turns up. Match the disc to the material, keep the guard on, and a 125mm grinder will handle cutting, grinding and masonry without you buying a second tool.
