AJB Temple
Finely figured
To the OP. From experience, a large scraper made to the exact radius is very difficult to use as you can't keep the burr in contact evenly and it is unwieldy.
I know this because years ago, when I was making guitars as a sideline, I made a couple of arch tops and I wanted a smooth concave undersurface. I made a scraper to fit half the required profile exactly (from an old saw as it happens). It didn't work well for the above reasons.
Years later I did a violin making course in Cremona for a few weeks. Brilliant fun, but you do need to speak the lingo or have a helper (wife in my case) who is fluent. Anyway there was a really old guy in the workshop making cellos and he was using a minuscule curved scraper, with a lot of elbow grease it seemed, to get really quite wide arches perfectly formed across a wide curve. I've copied his approach ever since.
I know this because years ago, when I was making guitars as a sideline, I made a couple of arch tops and I wanted a smooth concave undersurface. I made a scraper to fit half the required profile exactly (from an old saw as it happens). It didn't work well for the above reasons.
Years later I did a violin making course in Cremona for a few weeks. Brilliant fun, but you do need to speak the lingo or have a helper (wife in my case) who is fluent. Anyway there was a really old guy in the workshop making cellos and he was using a minuscule curved scraper, with a lot of elbow grease it seemed, to get really quite wide arches perfectly formed across a wide curve. I've copied his approach ever since.