But the digital readout caliper costs as much as the Cheap-o micrometer and you don't need the allen wrenches or to do any subtraction to figure out what the reading actually is.
I one already owns a digital readout micrometer then sure, go for it.
I have to say Dave, it's easier to read an inside micrometer than use your method. But neither are rocket science...
It's really not a safety issue. It's a serviceability issue. If the disk gets thin it is more apt to warp. If the disk warps you should replace the pads and disk together because the pads have taken the shape of the old disk surface. So the "idea" here is that it's a false economy to try to squeak more mileage out of a worn brake disk when you are already changing the pads.
My experience is: mos disks that warp do so long before they are worn to the spec. I seldom warp disks late in their life. It seems if the disk is a good one it stays true even after wearing beyond spec. Pads are relatively cheap. I just slap a new set of pads on regardless of if the disk (rotor) is worn or not.
Oh I can read a micrometer - and don't have to ask advice on how to measure disc thickness. Others, however, are different. And if you've never heard of some having difficulty in reading a micrometer you need to get out more...
It has far more uses than a micrometer. Not as accurate for the things you really need a micrometer for, of course, but a far more useful tool in general. You'd need several micrometers to cover the range of one.
Have you tried my method? It's not compulsory to use it - merely a alternative for the average DIYer who may not have a micrometer but does have a vernier calliper. And in the UK you'll get a vernier caliper in any DIY shed - but not a micrometer.
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