Pietenpol-List: wood grain
Posted: Wed Sep 26, 2001 8:44 am
Original Posted By: mboynton(at)excite.com
I think I have a handle on grain orientation so I'll give it a try. If Idon't, someone please correct me so I'll be right in the future.The analogy about a stack of straws is correct. A piece of wood resistscompression the most from the End Grain. If you imagine how the wood was inthe tree, it's strongest in it's resistance to gravity. So if you wanted tofabricate spacer blocks, it would be best to orient them so that the grainlines are parallel to the compression force.When determining what orientation is strongest for a long stick when it'sbent, it's the growth rings which are critical. A stick of wood with asquare cross-section can be viewed as a laminiated member using really badglue. The growth ring is the really bad glue. It's somewhat like a leafspring. It's very springy (or weak) when bent up or down but nearimpossible to bend it from the sides (in this illustration, the leafs areoriented horizontal as they are on a car). When working with wood, it is upto the design or designer on what is more important: the ability to easilybend around a curve or the ability to resist a bending force and this willdetermine the orientation of the growth rings.Robert HainesMurphysboro, Illinois*******Group,Sorry if this seems to be too much attention to detail, but the grainorientation thing has puzzled me for some time.In which grain orientation is wood most resistant to compression forces -when the grain is vertical to the force, that is, the grain lines are inline with (parallel to) the force when viewed from the end of the piece (notfrom the face of it), or when the grain lines are horizontal(perpendicular)to the force; and to help my feeble brain understand, why isit so?Thanks,Mark Boynton********________________________________________________________________________________Date: Wed, 26 Sep 2001 08:37:12 -0700 (PDT)
I think I have a handle on grain orientation so I'll give it a try. If Idon't, someone please correct me so I'll be right in the future.The analogy about a stack of straws is correct. A piece of wood resistscompression the most from the End Grain. If you imagine how the wood was inthe tree, it's strongest in it's resistance to gravity. So if you wanted tofabricate spacer blocks, it would be best to orient them so that the grainlines are parallel to the compression force.When determining what orientation is strongest for a long stick when it'sbent, it's the growth rings which are critical. A stick of wood with asquare cross-section can be viewed as a laminiated member using really badglue. The growth ring is the really bad glue. It's somewhat like a leafspring. It's very springy (or weak) when bent up or down but nearimpossible to bend it from the sides (in this illustration, the leafs areoriented horizontal as they are on a car). When working with wood, it is upto the design or designer on what is more important: the ability to easilybend around a curve or the ability to resist a bending force and this willdetermine the orientation of the growth rings.Robert HainesMurphysboro, Illinois*******Group,Sorry if this seems to be too much attention to detail, but the grainorientation thing has puzzled me for some time.In which grain orientation is wood most resistant to compression forces -when the grain is vertical to the force, that is, the grain lines are inline with (parallel to) the force when viewed from the end of the piece (notfrom the face of it), or when the grain lines are horizontal(perpendicular)to the force; and to help my feeble brain understand, why isit so?Thanks,Mark Boynton********________________________________________________________________________________Date: Wed, 26 Sep 2001 08:37:12 -0700 (PDT)