Woodworker's Journal 1984-8-6, страница 21
board surface. This method is not as economical as plainsawing, since it results in more waste. As mentioned earlier, however, with some species of wood, especially oak, the pronounced medullary rays that quartersawing brings out, make for unusually attrac- uppeRrt*LF(5E use. IS PLAIN LDWfcK. HALF op UJ& IS (ptiHSTLREtl AAJD SftliJfJ Fl6 Z +40W A LOfe ftcurr Tt> PRODUCE PLAIM AW&fpU^WTCRSsAWM tive figuring on the board surface. If there is an advantage to quarter-sawing lumber, it is that there is iess shrinkage across the face of the board and therefore less of a tendency toward cupping. Wood Shrinkage and Warping Though wood has its advantages over steel and other materials such as plastics, it is not nearly as stable in terms of dimension. Immediately after a tree is cut, the wood will begin to lose moisture into the atmosphere. Consequently, the wood shrinks. Conversely, even kiln-dried boards will expand slightly when they are subjected to an atmosphere of increased humidity. This is why in summer, when there is higher humidity, drawers stick and doors won't open. In winter, especially in homes using hot air or wood heat, boards can shrink and occasionally even crack. Chairs may get wobbly, panels may rattle in their frames, and pegs may loosen in their holes. There are three basic types of shrinkage, radial, tangential and longitudinal. Radial shrinkage reduces the thickness of the annual rings. With plain-sawn lumber radial shrinkage will affect the board thickness, as seen in Fig. 3A. With quartersawn wood radial shrinkage affects the width of the board (3B). How great can radial shrinkage be? For a freshly cut piece of white oak, if it is dried to 0% MC, the percentage of shrinkage will be about 4'/i%. For a piece of white pine, shrinkage will be about one half of that, or 2%. SHEJMKA&E CvOtErrH) 1 1 iMRiWKAfcE. (TWiCKME-SS) A Shrinkage gf R^VNJSAW^ S£WRD ITVii&iTlAL. ■ shrinkage ■ K^PiAL. -(WIDTH) ' (TUlCXAJESS) Fl£> 3 DECREE tPPSHRItOKA&E I6> StiA-iTJE T& KfW SftfiD iscur TO3M THE UH£i The type of shrinkage that a woodworker must be most aware of, however, is tangential shrinkage. This affects the length of the circumference of the rings. The classic illustration of this is a thin disc cut as a cross section of a log. A saw cut is then made from the outside to the center of the disc, and the disc is left standing upright in the sun to dry. As the moisture begins to evaporate into the atmosphere, the saw cut begins to open up (Fig. 4). cut<s>f&jsop Before AF-tek A U>& 03J>5S-SECTION Tangential shrinkage also answers a question asked by many woodworkers: Why do boards cup opposite to the curvature of the rings? Tangential shrinkage is the most common problem with plainsawn lumber. It is of particular concern to woodworkers because it affects board width to a significant degree. How great is tangential shrinkage? For the same woods, oak and pine, reduced to zero MC, the percentages are 8.8% and 6.1% respectively. The third type of shrinkage is longitudinal, or along the length of the board. The percentage of longitudinal shrinkage is usually between . 1 % and (continued on next page) Woodworkers' Hardware ORDER FORM Qty- Total TH^jprO Birch Mug Peg -——CJ s ,22/ea._ Birch Shaker Peg s .25 ea.„__, Oak Shaker Peg Birch 6 Inch _Furniture Spindles s>o^a. $ .42 93. _ a 1/2 inch - 3 .51 « a. *S4 Galley Spindle si.50/10. 2 Inch .Wood 3/4* T/S" 1" 11/4" 1 1/2" Wheels T5r»ii£ $3.57/C_ S4.77/C_ fB^MiS S5.00/C_ sTsra^'C se,oi/c_ £T»?»4/C SII.OI/C_ ^ ________ a" $ia.oo/c_ tf1 ri Ax|e Peg Fits 1"lo2" Wh»»t Wood Cargo oil Drum "Wvaj. 10 $2.31/ io_ Milk Can Jireo;io SI.BO/IO_ Pickle Barrel as: s^^oo $i.3i/ui_ Screw Hole Buttons 3/fl" S1.74/C_ 1/2" SlTVM^C S1.77/C_ Dowel Pins 3/s"*2" S1.77/C_ wood 3/4" sTrs«iio s.90/10. Knobs S7.77/C. ,1" flriaop si.4o/io_ S2"T^WLi.C Si 2.04/C 1/4- sTwao $i.so/io_ si3.eo/c_ w 'Screws 1 3'4'JWaaO Sz.20.10_ Saw Tooth Hangers ij-C S4.75/C. Picture Hanger "Sriaa^c S4.i7/c_ ,Clock Movements w/Hands 073 sflrsoja. SS.4B/M. S29.70/f_ Lazy Susan Bearing 3' S ,69/e»._ S ,9S'98._ SI,73/M.. Brass Plated Candle Cup S3.oo/1 o S29.40/C, Coat and Hat Hook SzTt*/^. S1.87/ea._ Brass Wreath S~B~SO^JO S5.10 10_ Brass Anchor Slrso-LIQ S3.30 10. Brass Pit. Eagle S"T^«~J0 S2.16'10_ Escutcheon Pins _ Brass Pins lor Above .57/C„ #929 Butt Hinge SITW^LS S1.08/10_ ■f F1 24 Screw lor Above $2.4 0/c_ Clipboard Clips 3" $ .3 5/sa.__ 6" S 59'ea._ Plastic Shelf Pins S5.40/C ________ Hoi. £ a 100 CalHloa S 1.00 or l'«0 wllti C'dtr Total Ordar _ Q Minimum Order !■ S2S.OO WN RM.- b » Ta. _ Order Amount : Shipping : Shipping _ S35.00 (0 S49.99 S3.S0 Tq|b1 EncloBad ___ s so.oo to tee.as S4.S0 —---- Owe, S 100.00 S5.00 Qvna □«nHr Cars GUARANTEE! SH3NAIIJBE _ r !■I.' _ NAM? __ ADDRESS . STATE MEISEL HARDWARE SPECIALTIES P.Q Bo» 258 J . Wound. Minnesota 55364 • <612) 472-5S44 |
