Hygrometer

[Greg Newell]

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Dale,
         Thanks for chiming in!!! Nice to hear your take on these things 
and things about your own setup. Comments interspersed below, k?

At 11:01 AM 8/31/2002, you wrote:
>In a message dated 8/30/2002 4:38:21 PM Pacific Daylight Time, 
>gnewell@ameritech.net writes:
>
>
>>Subj:Re: Hygrometer
>>Date:8/30/2002 4:38:21 PM Pacific Daylight Time
>>From:<mailto:gnewell@ameritech.net>gnewell@ameritech.net
>>Reply-to:<mailto:pianotech@ptg.org>pianotech@ptg.org
>>To:<mailto:pianotech@ptg.org>pianotech@ptg.org
>>Sent from the Internet
>>
>>              Greg
>
>
>                     I know this question wasn't directed at me but let me 
> share an answer with you.
>                In my setup I have a hot box I can store a few panels in. 
> On the door is a window and behind it is the radio shack temp and R.H 
> gauge. In side is a series of damp chasers and a small fan on the floor. 
> On the outside of the door I have a chart the tracks E.M.C. in 
> relationship to R.H. ie   90 degrees f. nets  5% emc in spruce. This is a 
> chart out of I believe the governments wood book

This sound like what I'm hoping to do. Since you have a glass panel in this 
you probably have it mounted on a wall right? I may have to go with the 
ceiling if I stay in my present location. No more space on the walls! Is 
your box vented in any way?

>    Any way if I want to be sure the board is suffienctly dry in modestly 
> humid weather I let it cook for three  days unless its been sitting in 
> the shop at 30% or less anyway. The fan circulating helps of course to 
> enenly dry all areas of the panel.
>      The same result will happen under a blanket with a space heater too. 
> Nothing wrong with the way Ron does it and his other point about the rib 
> set being the most critical factor should be pondered as much as this 
> current question on emc.

I was afraid my post would sound as though I was criticizing Ron's method. 
I really meant only to ask questions. I don't know enough to be critical 
yet. Only enough to be dangerous!!!

>      If your shop is humid without controls you'll want to rib the panel 
> in hour or so and don't answer the phone. If Rh is lower in the shop 
> that's different. My feeling is it takes a couple hours for the spruce to 
> take on insuffiecnt moisture to significantly change the outcome of your 
> rib crowned project.

I was afraid of that. I assume you use a go be deck? If not how do you get 
all the ribs on in that short amount of time. If your ribs are fanned do 
your clamps not run in to each other?

>      Remember the conditions which many soundboard were pressed up in the 
> Piano factories on the East coast were archaic at best. The zero EMC in 
> the winter and 80% with high temps in the summer. In your worst day in 
> your shop you'll all do better than that.
>    It sounds like there is a search for parameters in this discussion 
> which is important and when found will keep us from having undue  anxiety 
> in the board making process.

Parameters all ironed out? Sound like a lot to ask for but we can hope!!!

>    Best____Dale Erwin
>

Thanks Dale!

Greg

>>Ron,
>>         If I correctly understand what you are doing with your 
>> sophisticated :-) setup, you are looking for a change not necessarily a 
>> specific number from your meter. Correct? Do you feel that you can 
>> adequately state the moisture content of the wood from an instrument 
>> designed to measure the air simply because it is against the wood and 
>> trapped under a blanket? What would happen to the measurements if you 
>> introduced , say, a 6" air pocket around the hygrometer instead of 
>> having the blanket on top of the meter? Do you think that the readings 
>> would be different? the environment you create with the space heater 
>> under the piano is not necessarily the same environment above the board 
>> . Would you agree? If you measured the MC under and over the board they 
>> would surely be different, right? Could it be possible that some degree 
>> of instability is possible because of this? I know the board is 
>> relatively thin but without air circulating ! around the top could there 
>> be potential problems with uneven rates of contraction of wood fibers? 
>> Would this cause future problems with cracks or is this all semantics 
>> and nothing to worry about. Thanks for your indulgence of my random thoughts!
>>
>>Greg
>

Greg Newell
mailto:gnewell@ameritech.net
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