Hi Max, You are correct about grain running from one end to the other however if you remember that a tree grows with concentric rings as each year growth lays down another ring of cambium then you cut through it lengthways you can see from the end that the grain is arranged more or less in arcs.
So, if you cut a trunk in half right down the middle then place both flat sides down the grain rings are in the same direction. If you then cut each half again taking off an inch you now have two inch thinck boards and if you set one with the original face down and the other with the original face up then any cupping will occur in opposite directions. The grain still runs lengthwise. This cupping problem becomes more an issue as boards come out of the log nearer the outer edges. Clear as mud right? Hope this helps. Dale Leavens, Cochrane Ontario Canada [EMAIL PROTECTED] Skype DaleLeavens Come and meet Aurora, Nakita and Nanook at our polar bear habitat. ----- Original Message ----- From: Max Robinson To: [email protected] Sent: Thursday, August 02, 2007 9:40 PM Subject: Re: [BlindHandyMan] Expansion and Shrinking in Woodworking Projects Ray's message contained this sentence. When gluing up a few boards to make a table top, not only should the grain of each of the boards be in the same direction and boards be matched so that consecutive boards have similar colors, but the end grains should be in opposite directions. In other words, when one board is laid with the end grain (indicative of cupping) facing up, the next board should be facing down, then up, and so on. This will help "balance out" any cupping that may occur. I don't understand this. I thought grain ran from one end of the board to the other. Have I missed something? Evidently. Regards. Max. K 4 O D S. Email: [EMAIL PROTECTED] Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Music site: http://www.maxsmusicplace.com To subscribe to the fun with tubes group send an email to, [EMAIL PROTECTED] ----- Original Message ----- From: "Ray Boyce" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Saturday, August 04, 2007 10:14 PM Subject: [BlindHandyMan] Expansion and Shrinking in Woodworking Projects > Allowing for Expansion & Shrinking > Trees are comprised mostly of water. Any Boy Scout who has ever tried to > light a campfire with freshly-cut wood knows that such green wood is far > too > wet > to burn. This is because a tree's cellular structure is designed to allow > sap (which is mostly water) to flow throughout the tree. Some wood > varieties > literally drip with moisture when they are cut. > Freshly-cut wood is simply not conducive to woodworking, as it must be > dried > considerably. This is why lumber manufacturers will either store lumber > for > air-drying of bake it in ovens, called kiln-drying. > > Ideal stock for woodworking should be at a state of equilibrium with the > environment in which the finished project will reside. There are a few > considerations > to keep in mind here: > 1. Wood will either take humidity from or return humidity to the air. In > some climates, certain times of the year are much more humid than other > times. > The Upper Midwest of the U.S. is a perfect example: while summers are > quite > humid, winter air can be very dry, enough so that people will use > humidifiers > in the winter to put moisture into the air. This difference in seasonal > humidity is why doors and dresser drawers will stick in the summer time > but > move > freely in the winter. > > 2. A piece of furniture which is at a state of equilibrium with it's > environment when it is manufactured in a humid place like Miami will > undergo > an eventual > "culture shock" if it is moved to a dry location like Phoenix. Eventually, > the wood will give a lot of moisture to the air in an attempt to equalize > with > its environment. If the woodworker doesn't plan accordingly when building > the piece, cracking is a very real possibility. > How Does Wood Expand?: Knowing that wood will naturally attempt to > equalize > with the humidity in it's environment, a woodworker must know how the wood > will > expand. Movement in a piece of stock will occur across the grain, as > opposed > to along the grain. That is to say, a 1x6 that is four feet long will > almost > always stay four feet long. However, depending on the moisture content of > the stock and the air (and the variety of wood used), the width and > thickness > (to a lesser extent) may vary considerably. > Tips for Dealing With Expansion: When building a carcass for a cabinet, > each > of the four sides of the box should have the grain oriented in the same > direction. > As such, all four sides should grow relatively equally (particularly if > all > four come from the same piece of original stock). This, however, can cause > issues when drawers are used in the cabinet, making the drawers difficult > to > open & close. This is why most cabinet carcasses are built using plywood, > which isn't affected by humidity nearly as much as dimensional lumber. > When gluing up a few boards to make a table top, not only should the grain > of each of the boards be in the same direction and boards be matched so > that > consecutive boards have similar colors, but the end grains should be in > opposite directions. In other words, when one board is laid with the end > grain > (indicative of cupping) facing up, the next board should be facing down, > then up, and so on. This will help "balance out" any cupping that may > occur. > When orienting such a top on a structure such as a desk, it should be laid > so that the end-grains of the boards are on the two short sides of the > table. > To connect it the the top to the structure, screw the front side of the > desk > so that no movement can occur, but on the opposite (back) side, screws > should > be affixed in slots to allow the boards to widen or narrow. Failure to > account for such movement may eventually lead to cracking (shrinkage) or > excessive > cupping (expansion) in the table top. > > > > To listen to the show archives go to link > http://acbradio.org/handyman.html > or > ftp://ftp.acbradio.org/acbradio-archives/handyman/ > > The Pod Cast address for the Blind Handy Man Show is. > http://www.acbradio.org/news/xml/podcast.php?pgm=saturday > > Visit The Blind Handy Man Files Page To Review Contributions From Various > List Members At The Following address: > http://www.jaws-users.com/handyman/ > > Visit the archives page at the following address > http://www.mail-archive.com/[email protected]/ > > If you would like to join the Blind Computing list, then visit the > following address for more information: > http://jaws-users.com/mailman/listinfo/blind-computing_jaws-users.com > > For a complete list of email commands pertaining to the Blind Handy Man > list just send a blank message to: > [EMAIL PROTECTED] > Yahoo! Groups Links > > > > > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.476 / Virus Database: 269.11.2/933 - Release Date: 8/2/2007 > 2:22 PM > [Non-text portions of this message have been removed]
