help a beginner measure mc in wood with confidence

[Ron Nossaman]

> <I think you are correct and I was suspicious about the dried block - it 
> will never take up moisture like the un-dried blocks so even at 190 deg 
> f for 24 hrs something damaging must be happening to the wood.

As I understand it, oven drying a block is a one time thing. 
The block either comes from, or is stored with the wood you're 
monitoring, so it starts at an MC similar to the main batch. 
Weighing, oven drying, and again weighing one sacrificial 
block will fairly closely determine it's MC before drying, and 
by association, the MC of the rest of the batch. Each block is 
only used once.


>     So you don't have to measure MC directly (wood moisture meters do
>     not work reliably at MC of about 6% and below - so don't bother
>     buying a moisture meter). 

I agree. A moisture meter will be of little to no use to you.


>There are a number of ways to do this, I use a direct
>     and very simple method - it's got a complex name - don't let it
>     scare you  - ready? - "Direct
>     Linear Measurement" - i.e., put a tape measure across the panel and
>     measure it.

Another is to build a direct reading MC gage with a strip of 
spruce and a cheap dial indicator. Even if you don't bother to 
try to calibrate it to any specific MC, it can still be used 
as an indicator of dimensional change with Terry's approach 
without having to haul the panel out to measure it.


>     < Do you have the sling hygrometer? What brand and where did you get ?

Got one, but it's hard to swing in a 6" wide box. <G>


>     I suppose that after the board is ribbed, this same movement can be
>     measured as available crown with similar associations with changing
>     environment?

MC changes can be observed this way, but not measured, and not 
after the piano is strung. Crown in a strung piano doesn't 
usually vary much at all with MC changes.
Ron N
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