"Larry W" wrote:

I've seen the technique described elsewhere, but this was the first
google result on searching for "how to draw an arc of large radius"

Look at step 1 on this site:

http://www.instructables.com/id/How-...-Large-Curves/
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That will work, but it's hard work.

Check out a PDF File "Fig 5-42" over on apbw.

Lew