Brian Welch wrote:

>
> But it seems to me that the intended use was "enlarging holes in sheet
> materials" as Paul suggested in his original post.

I think I've found the answer, or a good approximation.

The answer is context -

In the modern era, cheap
and widely available twist bits make holes that are parallel
and accurate to size, at least for most purposes.

Only "high precision" work needs a (modern) reamer.

But the old blackmiths drill, with a diamond
shaped tip did NOT cut accurately to size,
did NOT cut parallel, and changed size with
every sharpening!

Hence a need to ream almost every hole.

  BugBear

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