Rib grain orientation

[Erwinspiano@aol.com]

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In a message dated 12/7/2002 5:58:15 AM Pacific Standard Time, 
sec@overspianos.com.au writes:

> Subj: Re: Rib grain orientation 
>  Date: 12/7/2002 5:58:15 AM Pacific Standard Time
>  From: <A HREF="mailto:sec@overspianos.com.au">sec@overspianos.com.au</A>
>  Reply-to: <A HREF="mailto:pianotech@ptg.org">pianotech@ptg.org</A>
>  To: <A HREF="mailto:pianotech@ptg.org">pianotech@ptg.org</A>
>  Sent from the Internet 
> 
>          Ron

                Honestly I wonder if it matters. I cut up some tight grain& 
dense old sugar pine stock from material gutted from a old pipe organ. Some 
of the pieces took on a beautiful tight arc appropriate for some tight radius 
treble ribs. The material is stiff and predisposed to this orientation 
already. It sounds like a good match ehh? I used some already. No worrys.
     If there was a slight stiffness difference it could be made up in rib 
thickness. No big deal. Ask some one in our engineering dept. if the wood 
strength formulas change for this slight change in orientation. (that would 
be you). I doubt  if it requieres a different calculation.
  Why would it be benificial to change the grain orientation to have the ray 
run the other way.I don't follow this.
    Regards
          Dale

> 
> Hi all,
>  
> 
> I have been wondering about the merit (one which seems to be a long 
> standing tradition) in orienting the rib grain such that the growth rings 
> run vertically, to set the medullary rays parallel to the sound board 
> panel.
>  
> 
> Now I can understand the logic behind this with the CC guys, since they are 
> likely to achieve a higher crown when the panel re-hydrates. However, in 
> the case of rib crowned construction, wouldn't it be advantageous to set 
> the grain in the rib such that the growth rings are horizontal and the 
> medullary rays perpendicular to the sound board panel? I am contemplating 
> setting the rib grain this way for piano no. 004 (both 004 and 005 are now 
> sold before completion, which is quite a relief).
>  
> 
> Dale, Del and Ron N., and any others who may be using RC construction. What 
> are your thoughts on this matter?
>  
> 
> By the way, we decided to build the cut-off as a laminated curve (I can't 
> remember if I've mentioned this previously on the list, since I had 
> originally planned to make it from scarfed material). We increased the 
> cut-off rail section size to 50 mm wide by 35 mm deep, using 17 laminates 
> of 2.9 mm thickness. I will try bending it with 4 mm laminates for piano 
> 006. When cutting and drum sanding the laminates at 3 mm it is quite 
> wasteful of wood. I'll get some photos of the buck and cut-off scanned and 
> onto the website soon.
>  
> 
> Ron O.
> -- 
> 


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