Violin Forum/Message Board

[kubasa]

I know there are a few discussions out there on how the top plate arching height is affected by humidity but what I'm struggling with is wrapping my brain around how exactly this happens. What are the mechanics of this change as related to arching height? I know it should be very simple but something is not clicking in my brain to make sense out of this so any help would be much appreciated!

James

[Chet Bishop]

Remember that the wood is attempting to expand (or contract) in three dimensions, but unequally, as it absorbs (or loses) moisture.

To simplify the mental image, cut it to just one dimension of change: laterally--and think of a single cross-section, through the C-bouts. Now you have a line describing a lazy parabola. What happens if the line gets longer (due to increased humidity), but the ends are anchored?

It has to raise the height of the parabola.

And the opposite is true as it dries.

Don't know if that helps.
_________________
Chet Bishop
https://bluefiddles.com
https://fivestringfiddles.com

[kubasa]

Thanks Chet. It's a long story how I ended up thinking about this but to make a long story short, I found out that my basement is a lot more damp than I thought it was! My workshop is down there and I have a dehumidifier but apparently I need to turn it up because I had a lot of shifting when i brought my last instrument upstairs - about 1 mm worth!

Anyway, thanks for the explanation. I read through it slowly and it made perfect sense. Sometimes I dislike being a visual person but at times it has it's advantages!