Sadly,
@thestelster is mostly right about that
@Chip Maker &
@Darren. If I had to use 123 blocks, I might as well keep using calipers. They are plenty good enough for most things at that size scale. I do have both 1 and 2 inch precision micrometers for the bottom end of the size scale. I'm really only after the bigger ones.
I agree with
@Darren about the need for trusted 123 blocks. Most of mine are pretty good as matched pairs but not great as an absolute reference. Especially not the 3" dimension. My 246 blocks are worse. All of them have their use but I don't think I'd trust them to calibrate a 5" micrometer.
My experience doesn't support a set and forget approach. I calibrate my current micrometers whenever I need to do precision work. They almost always need minor adjustment. I don't know why though. It has never bothered me all that much. Maybe it should. I was taught to always calibrate before any measurement session that matters. So I guess I just figured Calibration creep was part of the deal.
There is no doubt that gauge blocks would work just fine. However, they would soon get scratched with that much use. I only use gauge blocks to check the references I use for regular calibration measurements. I am prolly too anal about that but it's how I am. Despite the intended humour, Stel has me nailed pretty good.
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