Wire wheels, cut-off and flap discs on grinders

Reviewed Oct 8, 2026 by Site editor.

Most grinder jobs depend on putting the right wheel, brush or disc on the right tool and mounting it properly. These discussions follow that order: picking wire brushes and flap discs, getting cut-off discs to clamp, freeing a stuck nut, and cleaning a clogged bench-grinder wheel.

They are community discussions, most of them 15 to 20 years old or more, so read them for the reasoning rather than as current buying advice, and treat named products as examples. Grinders, wire brushes and discs can injure badly: unplug the grinder before changing or freeing an accessory, keep the guard on, wear eye and face protection, never run a wheel, brush or disc faster than the speed marked on it, and follow the instructions from the tool and accessory makers.

  1. 1. A wire wheel that rubs the grinder or will not centre visited done

    using a wire wheel brush with an angle grinder

    A flat wire wheel on a 4.5-inch angle grinder rubs the body and vibrates when spaced out. Replies say it is probably a bench-grinder wheel, that a brush should never be spaced out along the arbor, and recommend a threaded-hub brush. One warns a bench brush may fail at angle-grinder speed; another says 4-inch knot brushes are rated at 15,000 rpm or more and that the speed stamped on a brush is what counts.

  2. 2. Cup wire brushes: knotted or straight, steel or stainless? visited done

    Cup Wire brushes -- twisted vs non twisted

    For de-rusting with a cup brush on an angle grinder, most replies that compare the two prefer knotted brushes as stiffer and longer-lasting; one says straight wire gives a finer finish and suggests stainless for non-ferrous work. Several describe broken wires lodging in hands and a chest, and urge a shield, body protection, eye protection above all, and checking the brush's rated speed.

  3. 3. Flap discs that stop cutting mill scale visited done

    Getting More First Minutes Out of A Flap Disc

    A fresh flap disc strips rust and mill scale quickly, then soon barely touches the scale. Replies suggest a cleaning fleece disc instead, with a warning that many sold online are not rated fast enough for a 4.5-inch grinder, and an orbital air sander with coarse pads. Part of the thread is an off-topic argument.

  4. 4. Thin cut-off discs that spin loose under the nut visited done

    Loose Cutoof Discs in DeWalt DW400 angle grinder

    A thin cut-off disc on a 4.5-inch DeWalt grinder will not clamp even with the nut fully tight. Replies say that on several grinders the nut or outer flange is made to be turned over for thin discs, and point to purpose-made adapters and backing flanges, including one DeWalt sold for diamond wheels. Home-made shims are also suggested; nobody in the thread reports trying them.

  5. 5. Freeing a stuck flange nut visited done

    Dewalt Angle Grinder stuck nut?

    A nut over a thin cutting wheel will not come off. Replies say grinder spindles normally have right-hand threads, and one suggests gripping the disc along with the wrench. As a last resort one suggests breaking out the disc to relieve the pressure; another, only for a disc being thrown away, clamping it in a vise. One reply suggests greasing the threads on reassembly.

  6. 6. Cleaning a bench-grinder wheel clogged with aluminium visited done

    grinding wheel clogged with aluminum

    A stock bench-grinder wheel is loaded with aluminium. Replies agree it can be re-dressed but differ on how: a star dresser held on a solid rest, which an experienced reply calls the best choice for this job though wasteful of wheel; a dressing stick; a diamond dresser for touch-ups. One reply relays a claim that a metal-loaded wheel is more likely to burst, and another says aluminium belongs on a silicon carbide wheel.

Progress is kept only in this browser.