<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=US-ASCII">
<META content="MSHTML 6.00.2900.2802" name=GENERATOR></HEAD>
<BODY id=role_body style="FONT-SIZE: 10pt; COLOR: #000000; FONT-FAMILY: =
Arial"
bottomMargin=7 leftMargin=7 topMargin=7 rightMargin=7><FONT id=rol=
e_document
face=Arial color=#000000 size=2>
<DIV>
<DIV> Ron</DIV>
<DIV> By the way you sent this thru last week & I didn't have time=
to
say it was very well described & if one takes time to really anaylisze t=
he
dynamics of this rib design the vibrational effiecncy of this=
shape rib seems ... transparent. </DIV>
<DIV> The way you described it made it crystal clear i=
n my
thought process & I hope others. I catch on quick after a lo=
ng
time!</DIV>
<DIV> What about using the same approach with a solid rib.&n=
bsp;
The only difference in our procedure as to shape has been no=
t
using as much of a straight taper at the rib end. </DIV>
<DIV> Vibrational waves emanating at the bridge &
radiating outward is all s.o.p. thought and this rib design whether it be
laminated or not seems to aid the idea of the soundboards center as the star=
ting
point for vibration & also showing the most movement. </DIV>
<DIV> </DIV>
<DIV> Dale</DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid"><=
FONT
style="BACKGROUND-COLOR: transparent" face=Arial color=#000000
size=2><BR>> Are we say the same thing in a different
language? i.e.. A one inch <BR>> square rib until the=
taper begins?. Then it becomes ...tapered?<BR>>
Dale<BR><BR>Almost. Crowned top, flat bottom, taper feathering. I cut 'em
<BR>to depth on a table saw, so the thickest part is in the <BR>middle. I =
make
no attempt to keep the section depth constant <BR>through the center, and
would prefer not to even if I could <BR>easily do it. They're a taper of o=
ne
sort or another from the <BR>center point to just inside where they meet t=
he
rim. I want <BR>them to bend as uniformly as possible, like a bow, so stre=
ss
<BR>is evenly distributed and vibration response is from the whole <BR>rib=
(and membrane) at once. At least, that's the intent.<BR><BR>Make a 1/3-1/3=
-1/3
taper-straight-taper test rib, and another <BR>of the same dimensions with=
conventional tapering. Support the <BR>ends and load the center. The taper=
feathered rib forms a nice <BR>smooth continuous arc, or if it was constan=
t
radius crowned to <BR>begin with, it deflects to a nearly straight line un=
der
the <BR>right load. The conventionally feathered rib shows a tight <BR>ben=
d in
the feathered sections, a relatively straight run, and <BR>a relatively ti=
ght
bend in the center where the load is. The <BR>tight bends are the high str=
ess
areas. while the relatively <BR>straight sections aren't responding like t=
hey
could. The <BR>conventional rib shape just wasn't very well designed as a
<BR>load bearing member, which is why I use the shape I do. It <BR>does wh=
at I
think I want it to do.<BR><BR>If I had an easy way to do it, I'd probably
crown the bottom <BR>of the rib too, but the taper is easy and quick with =
a
router <BR>jig, even though it buries me in chips, and works pretty
well.<BR><BR>Ron
N<BR>_______________________________________________</FONT></BLOCKQUOTE></DI=
V>
<DIV></DIV>
<DIV> </DIV></FONT></BODY></HTML>