Pneumatic Soundboard Press

[Farrell]

I've been gluing my ribs onto the panel at 6% MC. Six percent MC equilibrium occurs at about 30% RH. I keep my shop at about 48% RH, but if I run my AC unit hard I can get the RH down to about 35% to 38% RH. I have measured the rate of MC change in a panel of spruce several times and find that it only varies a few tenths of a percent over the course of a day.

However, if you are drying the panel down to 4% or 5% MC and/or you are working in a garage without climate control in Homerville, GA in July - I'd have to do a bunch of calculations to tell you exactly how long it would take to get into trouble - but suffice to say that your soundboard panel would likely turn into a soggy potatoe chip before you could finish whistling Dixie.

Having several clamps - or one for each rib radii, if using several different radii - will allow you to move faster. If I recall correctly, my first soundboard took me about 10 or 12 hours to glue the ribs on using five clamps. I'm sure I will be doing this much more efficiently in the future, but if I have irrevocably screwed up my first board - well, that would have been rather disappointing.

The bottom line is that it is necessary to have good humidity control and to be able to work reasonably quickly. The best thing to do in an individual shop is to dry a chunk of wood down to the desired MC and then take it out into the shop environment where rib glue up would occur and measure the rate at which the MC increases. That way you will know. IMHO, this is a much better approach than scratching one's head wondering why this pianos sounds dead when the last piano was so nice and lively.

Also, I made clamps stackable. I can store my six clamps (I still haven't figured out why I made the sixth - wanna buy a clamp?) in a stack about three feet tall with a footprint of six feet by about 18 inches. I'm gonna make my rib clamps (see Ron, I got in now - clamps, not presses!) such that I can stack them on top of my rib-to-panel clamps.

Terry Farrell 
  
----- Original Message ----- 
From: "David Love" <davidlovepianos@earthlink.net>
To: "Pianotech" <pianotech@ptg.org>
Sent: Friday, August 08, 2003 11:40 PM
Subject: Re: Pneumatic Soundboard Press
> 
> Could you elaborate on that.  
> 
> David Love
 
> > [Original Message]
> > From: Farrell <mfarrel2@tampabay.rr.com>
> > To: Pianotech <pianotech@ptg.org>
> > Date: 8/8/2003 8:06:51 PM
> > Subject: Re: Pneumatic Soundboard Press
> >
> > One other thing to mention if going with one clamp. As the length of time
> for rib glue-up increases, the importance of adequate shop humidity control
> increases. Depending on what MC you are gluing your ribs onto your panel
> at, this could become a problem real fast.
> >
> > Terry Farrell