Anybody running a 6" brushless cordless grinder for structural jobs (paddle switch with kickback brake, guard on, tethered at height) — what battery size and discs are giving you the best runtime? I’m getting about 10 bevels on 3/8" plate per 8.0Ah pack using a 60-grit flap disc with a quick-change nut, but I want to squeeze more without compromising safety or cooking the tool.
I’ve gotten more runtime by switching to a 36–40 grit ceramic flap (Norton Blaze R980P: https://www.nortonabrasives.com/us/en/products/abrasives/coated-abrasives/flap-discs/blaze-r980p) and a HO 12.0Ah; on 3/8" I see about 14–16 bevels if I keep pressure light so rpm stays up — don’t gorilla it. Sticking with 8.0Ah, rough with a 6" ceramic fiber disc on a hard pad, then finish with your 60-grit flap; two quick passes beat one long roast. Are you on the 21700 High Output packs?
But swapping the quick‑change nut for the stock flange/locknut bumped me from “about 10 bevels” to 12–13 on 3/8" with a 60‑grit flap on an 8.0Ah, and the grinder ran cooler with less chatter… It’s slower for wheel changes at height, but with the guard on and a tether it’s been worth the extra runtime — would you ditch the quick‑change just for bevel runs?
Dropping to a 5" wheel on the same 6" grinder cut the load and bumped me from about 10 to about 14 bevels on 3/8 with an 8.0Ah high‑output (21700) pack — like shifting down a gear; swap to the 5" guard if you’ve got it. @samantha41’s flange tip pairs well with this and the head runs cooler. Are your packs the HO style or the older cells?
Swapping the flap for a 6" ceramic fibre disc on a hard backing pad (3M Cubitron II 982C: https://www.3m.com/3M/en_US/p/d/b00016630/) gave me about 15–18 bevels per 8.0Ah HO, since it bites faster with lighter pressure and runs cooler; just keep about 12–15° and don’t lean on it. Only caveat: watch sharp edges so you don’t chip the disc. You open to fibre at height?
@victoria61’s point about easing the load checks out — I pick up 2–3 more bevels per 8.0Ah in cold weather by keeping the pack warm in an insulated pouch between swaps; if it’s hot, park the spare in the shade so it doesn’t heat soak. Cold where you’re working?
I’ve had better luck switching to a conical (T29) 40‑grit ceramic flap and holding about 10–12°; it cuts quicker so the grinder isn’t pinned wide‑open as long, and I squeeze a couple extra out of the same pack… It’s a bit grabby at edges, so ease off near the end — like swapping to a sharper knife, you don’t have to lean on it; @taylor89’s point about easing the load lines up with this approach.
I’d ditch the “quick-change nut” and run the OEM low-profile flange; on my 6" brushless paddle/brake I consistently get 2–3 more bevels before swapping an 8.0Ah with a 60‑grit flap on 3/8" because it runs truer and I don’t have to lean as hard. If your grinder has a speed dial, back it off one click from max to tame the current spikes — still cuts fine if you keep the pressure light. Is the nut coming off hot, or is the backing hub the one cooking?