measuringtoolswooden-furniturewoodworking
I am working on a bookshelf which, due to the way I am building it, requires some of the pieces to be exactly measured to within 1/64th over 4-5 foot lengths. Obviously no yardstick is so accurate.
What techniques can be recommended for making such an accurate measurement?
I have access to machinist's tools, such as a complete set of gage blocks and machinist's squares and rules, however the rules I have are at most 16 inches long.
The material is white oak.
Find a stick the same length as your arm. Hold your arm out straight and level with the stick pointing straight up (90° to your outstretched arm). Walk forward/backward until the tip of the stick coincides with the top of the tree. Your feet are now at approximately the same distance from the tree as it is high. (For a more precise approximation, back up by the additional distance of the height of your arm above the ground.) The relationship is true only if the tree is significantly taller than you are, and the ground is relatively level. Time-tested logger method. Simple.
Forget it!!!! Trying to measure an untrue room for prefabrication of parts is nearly impossible. Your carpenter will have to come in, establish a center line in both axis and divide the differences on the edges. This application is no different than doing a suspended ceiling, and must be done on site. There will be a bit of adjustment in all directions, I'm sure.
Best Answer
Get yourself a good quality folding measuring stick like that pictured below. These have a slide out bar that allows for exact inside measurement transfers to be made.
One useful technique for marking in a precise manner is to use a sharp blade to make a cut mark instead of using a pencil. The cut is much finer than a pencil line.
Another useful technique if making multiple pieces the same length is to cut one length from some scrap wood and use it as a template length. Again use the blade to make a short cut mark for the length. Use of scrap piece helps to ensure you always use the same piece for measuring as opposed to picking up the 2nd or 3rd piece for the next measurement.