Destructive removal of a single-speed freewheel

The freewheel on my single-speed bike needed replacing. It closely resembles this one:

The two dimples are supposed to give a purchase-point for removing the outer casing, which has a reverse thread – it is screwed on very firmly indeed by the action of the chain when pedalling. Special tools are available for this but for the average DIY bike mechanic represent overkill, since this is a procedure one is only likely to need every few years, if that.

Various videos on YouTube show a punch being inserted into one of the dimples and then hammered. The dimples on my freewheel were too shallow for this: the punch kept slipping out. I was on the point of taking the whole wheel to a bike shop when I remembered that I own an angle grinder with a metal-cutting disc.

I removed the axle (which needed doing anyway, as I intended to service the hub) and, wearing an old jacket I don’t care about, laid the wheel on my workbench and braced it against the wall with my body, in such a position that the dimples were horizontally aligned. The brace is easier if you leave the (inflated) tyre on. Next, with the disc perpendicular to the wall, I cut a radial groove in the casing, just wide and deep enough to take the blade of an old and sturdy screwdriver. This groove served exactly the same purpose as the dimples in the videos: some energetic whacks with a 16 ounce hammer turned the casing clockwise until it could be unscrewed by hand.

Then I removed the cog and whatnot, leaving just the body of the freewheel still attached. This unscrews anti-clockwise in the usual fashion. I used my bench vice to grip it and tried turning the wheel, but the vice does not have serrated jaws as it is designed for woodworking and the freewheel body slipped. Instead I used a pipe wrench: this also needed quite a bit of force, but soon enough the freewheel body came loose and could be unscrewed the rest of the way by hand.

I am putting this out there because nowhere else have I seen the use of an angle grinder recommended. Of course, this will be no good if you just want to clean and lubricate your freewheel, but they are cheap enough to buy if you find non-destructive removal impossible.