How to use a 230mm diamond blade on a 9 inch grinder
Updated: 21 October 2026
The line is marked and the disc is still in the box. How to use a 230mm diamond blade is the sequence before the rim touches masonry: inspect the disc, fit it under a 230 mm guard, match the arrow, stay under the speed mark, and keep silica dust under control. Which disc to buy sits on the [230mm diamond cutting disc comparison](/hub/sanders/230mm-diamond-cutting-disc). The Products Compared editorial team used the saved amazon.co.uk listings and public HSE and FEPA notes on 19 October 2026. We did not run a cut. A qualifying Amazon purchase can earn a commission at no extra cost to you.
The line is marked and the disc is still in the box.
The line is marked and the disc is still in the box. How to use a 230mm diamond blade is the sequence before the rim touches masonry: inspect the disc, fit it under a 230 mm guard, match the arrow, stay under the speed mark, and keep silica dust under control. Which disc to buy sits on the 230mm diamond cutting disc comparison. The Products Compared editorial team used the saved amazon.co.uk listings and public HSE and FEPA notes on 19 October 2026. We did not run a cut. A qualifying Amazon purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Bore | Max speed | EN 13236 | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Bosch Bosch EXPERT diamond cutting disc | 22.23 mm | Not stated | Not stated | 9.6 | about £84.43 | View offer |
| Best value |  TopsTools TopsTools TTDS230 | 22.23 mm | Not stated | Not stated | 9.2 | about £8.99 | View offer |
 Blue Spot Blue Spot 19549 twin pack | 22.23 mm | 6,600 rpm | Stated | 9.0 | about £15.10 | View offer |
On this page
Before you fit the disc
FEPA says you should inspect a diamond saw before you fit it. A dropped disc is a stop even when it looks straight. Bore and rim checks are on the 230mm diamond cutting disc buying guide.
The machine has to be a 230 mm grinder with the guard made for that diameter. A 115 mm or 125 mm grinder is the wrong machine for every disc in this set. Bosch part 2608602397 is titled for small grinders, but Bosch UK lists it as 230 mm. Trust the diameter on the disc.
Read the speed marks while the grinder is unplugged. Tech Traders prints 6,650 rpm and Blue Spot prints 6,600 rpm. Most other rows leave the maximum blank, so stay under the lower figure you can actually read. Do not exceed the marked speed, and keep the guard on.
Mounting on the spindle
The hole is 22.23 mm. Listings that print 22.2 mm, including S&R and Tech Traders, describe that same fit. M14 is the spindle thread, not the hole. If the disc rattles, take it off. Do not pack the hole with a washer the box does not contain. Use the flanges that came with the grinder, clean of old slurry, and the same size on each face of the core. Tighten the nut until it is firm, then stop.
The arrow points the same way as the spindle turns. If you cannot find an arrow, do not guess from the shape of the teeth. Run the grinder for a few seconds with no cut, stood so a failure throws away from you. Any wobble on that test run means the disc comes off and stays off.
Letting the diamond cut
Support the workpiece so the offcut cannot drop and close the kerf. Keep both hands on the grinder and let the diamonds work. Forcing the disc, or twisting it in the slot, side-loads a rim built to cut in its own plane. These listings do not state one depth of cut. On thick concrete, a series of passes beats one plunge toward the flange. If the steel core starts to colour from heat, that disc is finished.
On a patio corner, a short relief cut before the long run gives the waste a place to break. Slab support is on diamond blade for paving slabs. Stop when a segment cracks, a piece of rim is missing, or the disc wobbles after a knock. Structural concrete and any site where you cannot keep people out of the line of the cut are the point to put the grinder down.
Dust, water, and the point you stop
Concrete, brick, mortar, and stone release respirable crystalline silica. HSE’s workplace exposure limit, in CIS54, is 0.1 mg/m³ over 8 hours. The controls named for grinding are water, or an M-class or H-class extractor, plus respiratory protection at APF 20. Keep slurry wet. Dry sweeping puts the dust back into the air.
A wet-or-dry line, including on DeWalt DT40260, does not make a closed room acceptable. Unplug the grinder before you change the disc. A cracked segment means that disc is finished.
Common questions
Which way does the arrow point?
The arrow on the disc points in the direction the spindle turns. Match it to the rotation mark on the guard before you finish tightening the nut. On the Bosch PRO listing, a reviewer thought the teeth looked backwards and then said that look is normal when the arrow is followed. Fitted the other way, the disc can snatch and the bond wears faster. If there is no arrow, do not infer direction from the segment shape.
Do I need water on a segmented disc?
Many segmented discs here are sold for wet or dry use, and DeWalt DT40260 says so in the bullets. A dry cut is still a silica cut. HSE’s controls are water, or an M-class or H-class extractor, and respiratory protection at APF 20. On a patio, wet the line and keep the slurry wet. Indoors, a dry cut with no extraction is the job to hand over.
Can I take the guard off to see the line?
The guard stays on for the whole cut. HSE’s HSG17 treats guarding as part of using the wheel, and a 230 mm disc needs the guard made for that diameter. Removing it to watch a pencil line puts your hands and face where a segment can fly. Mark the line so you can follow it with the guard in place.
What if the disc wobbles after a drop?
Take it off and do not refit it. FEPA tells you to inspect a diamond saw before fitting, and a drop can crack a segment or bend the core when the wobble still looks small. The same stop applies if the test run wobbles before you touch the material. Replace the disc. A burst wheel is a point to stop the job.
How deep should one pass be?
None of these listings states a single depth of cut, so there is no figure to treat as a specification. Let the diamond cut, and take more than one pass on thick concrete rather than plunging toward the flange. Twisting the disc to deepen the slot loads the rim sideways. If the steel core turns blue, that disc is finished.
Related pages
Sources
Sources taken from the research digest. Listings were checked on 19.10.2026.
- HSE — Scabbling or grinding (retrieved 19.10.2026)
- HSE — CIS54 Respirable crystalline silica (retrieved 19.10.2026)
- HSE — CN6 Cutting paving and kerbs (retrieved 19.10.2026)
- HSE — CN2 Chasing with hand-held tools (retrieved 19.10.2026)
- HSE — HSG17 Safety in the use of abrasive wheels (retrieved 19.10.2026)
- FEPA — Diamond saws on angle grinders (retrieved 19.10.2026)
- Norton UK — Segmented versus continuous diamond blades (retrieved 19.10.2026)
- Bosch Professional UK — 2608602397 turbo disc (retrieved 19.10.2026)