Thanks Sid, that's exactly what I needed to know. Cheers,
Tony King Sent from my iPhone On 26/05/2012, at 9:55 AM, "smwood" <smw...@md.metrocast.net> wrote: > Orientation does matter. For a given same cross section of the same type > lumber, the horizontal layering in a beam is about 15 percent stronger > according to a Forest Service handbook that I read about 25 years ago when I > was contemplating the same construction on my KR-2 spars. > The basic reason why is: Putting the layer lamination vertical will induce > shear stress in each piece of lumber when it is loaded ( pulling g's, hard > landings, turbulence, etc.). That is in addition to the compression or > tension load that the spar pieces would be handling. This tends to break > the grain along the length of the lumber. The glue (epoxy) that you will be > using is much stronger than the resin bonds that the tree has put between > each individual wood fiber. So, the horizontal layering can handle the > shear stress much better. > And the thinner the layers for the same built-up cross section, the stronger > will be the finished product. There is a limit regarding how much epoxy > gets added versus the volume of timber in order to keep the weight to > strength ratio in bounds. > > Sid Wood > Tri-gear KR-2 N6242 > Mechanicsville, MD, USA > smw...@md.metrocast.net > > ------------------------------ > > I'm about to start laminating the timber to form my centre section > spars from pieces that are 19mm (3/4") thick. Is the orientation of > the laminations significant? I'm not sure why but all the laminated > timber beams I've seen have the lamination layer horizontal. I can do > this but in this case I'd waste less wood if the laminations were > vertical. Does it matter? > > Cheers, > > Tony King > > > > ------------------------------ > > > > > _______________________________________ > Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. > To UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html
