<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> <body bgcolor="#FFFFFF">   Sarah Fox wrote: <blockquote TYPE=CITE><style></style> Hi Terry, OK, here's a more user-friendly method for you that will give you the correct position of the rib anywhere along its length.  (You can also use this method to plot out points on a template.  Compute numerous points and connect the dots.  :-) Clamp any part of the rib against a flat surface, concave side up (soundboard side down).  With this arrangement, let: h = the height of the rib above the flat surface r = radius of the rib d = the distance along the rib you are measuring, with respect to the clamp point.  For instance, if you clamp in at the middle of a 4 ft rib and measure at the end, d would be 2.  Of course this is approximate.  More accurately, d would be the distance from the clamp point to the position on the flat surface, directly underlying the measurement point.  (Think right triangles.) Then: h = r - Sqrt ( r^2 - d^2) </blockquote> Which is exactly what I wrote in my last post, exept I didnt specify that you could measure anywhere along the rib... figuring that was kind of self explanitory.. :) ""You could also do this simply by   r - Sqrt( r ^2 - (0.5L)^2)   L being the length of the rib. ""   What I thought was neat about all the replies... is that we came out with two basic approaches... solving for crownheight, and solving for radius. So you can check either way you set up your rib jig. If you want a 60 foot radius.. then use the above... if you want to use a certain crownheight and want to be sure what radius you are imposing.. then use the formula Ron N put out. Cheers RicB   -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway <A HREF="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A> <A HREF="http://home.broadpark.no/~rbrekne/ricmain.html">http://home.broadpark.no/~rbrekne/ricmain.html</A> <A HREF="http://www.hf.uib.no/grieg/personer/cv_RB.html">http://www.hf.uib.no/grieg/personer/cv_RB.html</A>   </body> </html>