The usable depth is roughly the disc radius minus the guard and flange — around 25 to 30 mm (0.98 to 1.18 in) on a new 115 mm (4.53 in) disc. As the disc wears down, that figure drops, and a well-used disc may reach barely half of it.
Cutting deeper than the disc allows means tilting it in the cut, which is how discs bind and shatter.
The questions welders ask
How should I cut something thicker?
From both sides, marking the line right round first so the two cuts meet. Or with a larger machine, a band saw or a chop saw. What does not work is forcing a small disc deeper than its geometry allows by leaning the grinder over.
Last reviewed 2026-08-14