Amiga Plus 1995 #2

home *** CD-ROM | disk | FTP | other *** search

/ Amiga Plus 1995 #2 / Amiga Plus CD - 1995 - No. 2.iso / internet / faq / englisch / rec.woodworking < prev next >

Wrap

Text File | 1995-04-11 | 31.1 KB | 747 lines

Archive-name: woodworking/faq/faq Last-modified: 12/30/94 Copyright (c) 1994 by James J. Roche. All rights reserved. I have been reading and archiving rec.woodworking since its inception as net.rec.wood back in 1984. Below are some of the topics that seem to come up frequently. If you have any constructive comments please let me know. If there is something you would like to see added please pass it on to me. TABLE OF CONTENTS: 1). Should I buy a table saw or a radial arm saw? 2). Which type of dado blade should I buy, the dial (wobble type) or the stacking (chipper type)? 3). How do I cut the perfect dado if both types of dado blades have shortcomings? 4). Should I buy a Sears blurfl? 5). Should I buy a Taiwanese clone blurfl? 6). How do I remove paint? 7). Should I use a hot melt glue gun for my next project? 8). Where can I get plans for the New Yankee Workshop projects? 9). What is the best woodworking magazine? 10). What is a board foot? 11). What is the correct way to handle the glue squeeze out problem? 12). What books should I purchase to learn about various aspects of woodworking? 13). How do I finish toys so that they are non-toxic? 14). What size drill bit do I use for a wood screw? 15). How do I finish the edge of plywood? 16). Which saw blade should I buy? 17). Where are the archives for rec.woodworking? 18). Where can I find cradle plans? 19). Where can I find futon plans? 20). Where can I get information about particle board? 21). What are some of the common woodworking terms/abbreviations? 22). How do I finish a cutting board? 23). What is snipe and how do I eliminate it? 24). How is lumber graded? 1). Should I buy a table saw or a radial arm saw? Table saws work best for ripping. Radial arm saws work best for crosscutting, but are limited by their arm's length. Both saws will perform both tasks. The radial arm is more adaptable for non-sawing tasks. For instance, overhead routing, surface planing, and drum sanding attachments are available for some radial arm saws. You can buy a disk sanding attachment for use on most table saws. Ripping on the radial arm saw is difficult because it is necessary to push the lumber under the motor housing. This problem can be minimized by use of pushsticks and holddown wheels. Maximum rip width is normally limited by the length of the arm. Building a secondary rip fence on the other side of the table from the column will enable you to rip wider pieces, but the off-cut piece width is then limited. Radial arm saws are more prone to overheating during rips in thick wood since the teeth stay in the cut longer, unless you cut substantially into the table top and even then there is no place for the sawdust to exit. Crosscutting on the table saw is difficult because it is tough to keep a board much longer than 4 ft square to the blade. This problem can be minimized by building a good sliding panel cutter. Some table saws have built-in sliding tables, and aftermarket sliding table attachments are available for most saws. A couple of saws have sliding arbors, enabling them to work as inverted radial arm saws. The arbors typically don't slide as far as the length of many radial arms (for a review of 2 of these saws, see the April 1992 issue of FWW). Both saws are capable of accurate work. The radial arm saw, with its cantilevered arm attached to a cantilevered column, is typically less rigid than the table saw, which usually have their arbor trunions bolted to the table in a wide pattern. Worn arm bearing in radial arm saws can also contribute to wander in the cut. In table saws, play of the miter gauge bar will adversely affect accuracy. Both table saws and radial arm saws need to be aligned to work optimally. There are more aligning tasks to be performed on a radial arm saw than on a table saw. Radial arm saws typically require realignment more frequently than table saw, perhaps because of the stresses put on the cantilevered assemblies. Radial arm saws don't need as much space around them as table saws for performing equivalent tasks. On the radial arm saw, boards are always oriented the same way whether you are ripping or crosscutting, so you need space to the left and right of the blade, and only as wide as the widest board you're cutting. On the table saws, boards are oriented at right angles depending on whether you're ripping or crosscutting. Thus, you need space in front and in back for ripping, and to the left and right as well for crosscutting. It seems to be easier to engineer and manufacture a table saw than a radial arm saw, which has more moving parts that must withstand large forces without deflection or play. It can therefore be argued that if you're on a budget, a cheap table saw may work better for you than a cheap radial arm saw. Some people say the radial arm saw is more dangerous because the blade is exposed above the work surface, and because the blade's location varies as the cut progresses. Angled crosscutting is particularly dangerous since the blade is now cutting where one normally holds the work. The spin direction of the blade tends to lift the work off of the table when ripping, and can pull the carriage into the work (resulting in binding of the saw or serious injury to a careless operator) in the crosscut position. So-called "safety-blades" have a shoulder in front of each tooth, thus limiting the amount of pull generated and reducing these tendencies. Some people say the table saw is more dangerous because you can't see where the blade is like you can with the radial arm saw. On the other hand, the blade is always in the same spot on the table. The spin action of the table saw's blade tends to keep the work down on the table, but it can also throw the work, and off-cuts, back at the operator. Both machines are very dangerous and should be treated with much respect. As with all tool buying decisions, you should consider your intended applications, both now and in the future. The general consensus is that if you're building things like jungle gyms, house additions, or trim work (moldings), a radial arm saw may be best. If you're building things like fine furniture or cabinets, a table saw may be more a more appropriate choice. A number of people have reported that the addition of a motorized miter box to a table saw is a satisfying combination. Taunton Press publishes a softcover book titled "Fine Woodworking on The Small Workshop." It contains a number of articles on designing and buying equipment for small shops, but is geared to furnituremaking. The majority of the recommendations are for getting a table saw first, with one writer claiming a bandsaw is the first tool to buy. 2). Which type of dado blade should I buy, the dial (wobble type) or the stacking (chipper type)? The wobble type is very simple to use with infinite settings between approximately 1/4 inch and 13/16 inch. It does not produce true right angle cuts because of the design. The chipper type doesn't have the same infinite setting for width. You can achieve nearly infinite settings by adding shims with thicknesses of 1/32, 1/64, 1/128, etc. It will cut a square bottom on the dado, but it will also leave 2 grooves on the edges of the dado. The reason for this is that the blades are slightly larger than the chippers. The larger blades are to reduce the splintering. The blades can be reground to be equal to the size of the chippers at the possible cost of increased splintering. Some say the grooves are a benefit because they provide relief for gluing joints. Many people claim that the wobble type is easier to set up. The August 1991 Fine Woodworking further studies the features of the various types of dado blades. 3). How do I cut the perfect dado if both types of dado blades have shortcomings? Your best bet would be to cut it with a router. 4). Should I buy a Sears blurfl? Most people agree that the Sears stationary power tools sold today aren't the same quality as the Sears tools sold 20 years ago. It can be argued that if you can't afford to buy a Delta, then you should be looking at one of the Taiwanese clones rather than looking at Sears. 5). Should I buy a Taiwanese clone blurfl? It depends on how much money you have. If you can afford the Delta blurfl you should probably get it. Buyers should be wary that not all Taiwanese clones are quality machines. The general consensus is that Grizzly has good quality control. It should be noted that some of Delta tools are now being made in Taiwan. One would hope that Delta quality control is better than some of the cheaper imports. 6). How do I remove paint? There are many ways to strip paint from wood. Paint can be removed by scraping and/or sanding. Paint can be removed by using chemical paint removers. Paint can be removed by using heat. Paint can be removed by sandblasting. Paint can be removed by a new product known as Peel-Away. Rumor has it that oven cleaner also works. If you know of another way to remove paint please feel free to pass the information along. 7). Should I use a hot melt glue gun for my next project? The general consensus is that hot melt glue is not adequate for woodworking projects. However, hot melt glue guns can have a place in the shop. Many people like to use them for tacking items together such as when building forms or jigs. 8) Where can I get plans for the New Yankee Workshop projects? Plans for any of Norm's projects can be ordered for $7.50 from (project name) New Yankee Workshop P.O. Box 645 Bedford, MA 01730 Videos, which include a copy of the plans, cost $24.95 plus shipping and handling, from 800-272-0280. Both the address and phone number are given at the end of each show. Most of the projects from the first two seasons are in the two New Yankee Workshop books. For the workbench, one important dimension is *not* given in the book, though it can, I think, be calculated. 9) What is the best woodworking magazine? There are many good woodworking magazines. Two that are frequently recommended in this group are Fine Woodworking and Woodsmith. Fine Woodworking is a bit on the artsy side and more for the experienced woodworker. It does not get into the small details of a project. Woodsmith provides much more details for projects. Woodsmith is well suited for both the amateur and experienced woodworker. 10) What is a board foot? A board foot is a common unit used in the measurement of wood. It is equal to 1 foot length x 1 foot width x 1 inch thick. It should be noted that the thickness is nominal thickness. After drying and surfacing the usual thickness of a 1 inch board is 13/16. A board 10 feet long x 1 foot wide x 2 inches thick would be equal to 20 board feet. 11) What is the correct way to handle the glue squeeze out problem? Use the right amount of glue. The (obvious) danger is a glue starved joint. Wipe off the excess glue immediately with a damp sponge or paper towel. This method gets mixed reviews. Some claim the water-glue mixture will soak into the wood and show up when the piece is finished. Others say that this is not a problem. The effectiveness of this method probably depends on the type of wood and finish that are used. Allow the glue to harden somewhat (1/2 - 2 hrs) and then chisel/scrape it off. Some recommend removing the glue after it begins to film over. Either finish the pieces ahead of time or apply paste wax. This should prevent the glue from sticking. The problem with this is removing the paste wax prior to finishing. Use a plastic drinking straw cut at 45 degrees to scoop the glue out of the inside corner. As the straw fills up, it can be trimmed to provide a fresh surface. 12) What books should I purchase to learn about various aspects of woodworking? Thanks to Ken Smith (kensmith@cs.Buffalo.EDU) for providing the ISBN numbers along with a couple of additions to the list. GENERAL WOODWORKING Cabinetmaking and Millwork - John L. Feirer ISBN 0-02-675950-0 New Yankee Workshop - Norm Abram ISBN 0-316-00454-5 Classics From The New Yankee Workshop - Norm Abram ISBN 0-316-00455-3 Mostly Shaker - Norm Abram ISBN 0-316-00473-1 Encyclopedia of Furniture Making - Ernest Joyce ISBN 0-8069-6441-3 FINISHING The Woodfinishing Book - Michael Dresdner ISBN 1-56158-037-6 INTRODUCTORY WOODWORKING Basic Woodworking - Sunset Books ISBN 0-376-0-1628-0 JOINERY Tage Frid Teaches Woodworking: Joinery Tools and Techniques - Tage Frid ISBN 0-918804-03-5 Tage Frid Teaches Woodworking: Shaping, Veneering, Finishing - Tage Frid ISBN 0-918804-11-6 (out of print though) Tage Frid Teaches Woodworking: Furniture Projects - Tage Frid ISBN 0-918804-40-X TOOLS Router Jigs and Techniques - Patrick Spielman ISBN 0-8069-6694-7 200 Original Shop Aids & Jigs for Woodworkers -Rosario Capotosto WOOD Understanding Wood - R. Bruce Hoadley ISBN 0-918804-05-1 13) How do I finish toys so that they are non-toxic? a. Behlens Salad Bowl Finish. This product has been approved by the FDA for use on objects that will come in contact with food. It produces a nice, semi-gloss finish. (Apparently the can no longer states the FDA approval, but product is still safe for food contact after appropriate drying time - 12/30/94). b. Any vegetable oil. Could become rancid after a period of time. c. Walnut oil. It reacts with the air and hardens into a true finish. It works particularly well when the oil is heated and the item is dipped into the warm oil. Available at health food or large grocery stores. Don't buy the gourmet stuff! d. Mineral oil or vaseline. e. Water-based polyurethanes. These are new products which are very different from the more familiar oil-based polyurethanes. They are totally non-toxic, dry quickly, and have no strong odors when applying. f. Pure Tung Oil. It has no driers or solvents. It is essentially just a vegetable oil but produces a nice finish that won't go rancid. Use only Tung Oil that is "pure". g. Rumor has it that shellac is also safe once it dries. I have been unable to verify this. h. Watco claims its oils are suitable for food or baby use if they've been allowed to dry for 30 days or more. They claim that it takes this time for full polymerization. i. Paint. Some paints claim to be non-toxic when dry. h. Leave items unfinished. If you are unsure about any finish you plan to use, contact the manufacturer and request the information. You can also request an MSDS (Materials Safety Data Sheet). 14) What size drill bit do I use for a wood screw? Screw Gage Shank Shank Pilot Pilot Number Hole Size Soft Wd Hard Wd 0 1/16 .060 1/64 1/32 1 5/64 .073 1/32 1/32 2 3/32 .086 1/32 3/64 3 7/64 .099 3/64 1/16 4 7/64 .112 3/64 1/16 5 1/8 .125 1/16 5/64 6 9/64 .138 1/16 5/64 7 5/32 .151 1/16 3/32 8 11/64 .164 5/64 3/32 9 3/16 .177 5/64 7/64 10 3/16 .190 3/32 7/64 11 13/64 3/32 1/8 12 7/32 .216 7/64 1/8 14 1/4 .242 7/64 9/64 16 17/64 .268 9/64 5/32 18 19/64 .294 9/64 3/16 20 21/64 .320 11/64 13/64 15) How do I finish the edge of plywood? a) Wood tape. It comes in 2 forms, one that can be ironed on, and one that can be contact cemented on. The tape is approximately 1 inch wide, and can be trimmed with a plane, router, or knife. b) Glue strips of wood, either purchased or cut from lumber. 16). Which saw blade should I buy? There is an excellent article on evaluating carbide tipped sawblades in issue #72 of Fine Homebuilding (March 1992). To summarize the article: An expensive blade will typically last longer than a cheap blade and the cost difference is made up by the number of extra sharpenings available from the investment. A blade that has been tensioned will run truer and cost more than a blade that hasn't been tensioned. Carbide blades will last up to 60 times longer than steel blades. 17). Where are the archives for rec.woodworking? There are 3 archives that I know about. The first is ftp.cs.purdue.edu in /pub/sjc/woodworking. Currently it contains a list of Woodsmith plans. The second is <ftp://ftp.cs.rochester.edu/pub/archives/rec.woodworking>. Currently it contains summaries of past discussions of tools, some safety related notes, and some of the FAQ postings. Below is the current list of files available for ftp from cs.rochester.edu: 15496 Sep 28 14:48 address 128083 Oct 7 11:36 bandsaw 51637 Sep 28 15:21 biscuit_joiners 6125 Oct 28 09:13 crib_safety 42264 Oct 1 09:05 dust_collect 106944 Sep 29 09:29 jointer 15746 Sep 28 16:03 miter_saw 16610 Oct 5 13:39 motors 52704 Sep 29 10:51 planer 44905 Oct 1 14:15 radial_saw 140134 Oct 6 13:01 routers 54977 Feb 19 11:19 ryobi.bt3000 48837 Oct 27 10:35 sander_belt 42432 Oct 27 10:39 sander_misc 47661 Oct 27 10:40 sander_random-orbit 7975 Feb 5 12:44 sawzall 34745 Oct 1 09:23 scrollsaw 27066 Nov 12 11:27 shop_heat 26377 Oct 28 09:17 toy_safety The third is petroglyph.cl.msu.edu (or 35.8.3.50). FTP: /pub/woodwork/images/furniture URL (World Wide Web client): Use your favorite WWW client to open the URL: http://petroglyph.cl.msu.edu/~tigger/WoodWorkPhoto.html For example using Mosaic, you could type: Mosaic http://petroglyph.cl.msu.edu/~tigger/WoodWorkPhoto.html 18). Where can I find cradle plans? 1. Garrett Wade $9.95 for plans for a "rocking cradle item number 14A03.SA in their 1993 tools catalog 2. The Woodworkers' Store $4.95 for plans for a "four post cradle" item number 40360 in their 1991-2 catalog 3. The August 1990 issue of Fine Woodworking has an article about making a cradle. 4. Bartley offers a cradle kit for $199. If it's up to the quality of their other kits, this should be good. 5. Woodsmith issue #48 - cradle with frame and panel ends with arched-top panels. 19). Where can I find futon plans? 1. TODAYS WOODWORKER JULY/AUG 1989, VOL 1 NO. 4 Queen size futon folded in half length wise. Very attractive Futon sofa bed frame for queen size futon (possibly Swedish modern). Unfolds to make bed, breaks down for moving. Elegant design with lots of mortise and tenon joinery. 2. WOODWORKER'S JOURNAL NOV/DEC 1992 VOL 16 NO. 6 "Standard" futon frame for standard 2 fold futon. Classic bi fold futon frame for queen size futon. The plans claim to be (and appear to be) appropriate for "even beginning woodworkers". 3. Fine Woodworking July/August '89 NO. 77 4. Specialty Furniture Designs (800-892-4026) Design "WSN-15" $14.95 Catalog $2.00 Attractive (modern) Sofa like futon frame fro singe fold futon (futon folds once (the long way)). Plans for both twin (39 x 75) and full (54 x 75). Plans are a large single sheet of blue print like drawings with associated text, construction looks reasonable and pictures of the finished project look good, but the plans are a bit intimidating 5. Popular Woodworking SEP 1992, issue #68 "Knock-Down Couch" Attractive Mission / Craftsman like design for a sturdy, knock-down couch. The plans are not specifically for futons but could be easily adapted to a single fold futon (might not need to be adapted). 6. Today's Woodworker, Volume 26, Page 8 Contemporary Futon Sofa Bed 7. The Family Handyman Volume 6/94, Page 72 Double Bed Futon Sofa 20). Where can I get information about particle board? The following was provided by Stavros Macrakis (macrakis@osf.org) and was added to the FAQ with his permission. ********************************************************************* For technical information on particleboard (PB), the National Particleboard Association puts out some very nice free pamphlets, which I summarize below. Although they are basically addressed to industrial users, they cover particleboard joint techniques quite well for the rest of us. Some of the facts about joints are very surprising. I've tried to summarize the essential information below, but you can also order copies from: NPA, 18928 Premiere Court, Gaithersburg, MD 20879. Specifier's Guide to PB and MDF Abstract There are 15 ANSI grades of particleboard, with diverse properties. For instance, face screwing strength varies from 90-450 lb, stiffness from 80,000-500,000 psi. Recommendations are given for matching grade to use. Dowel Holding Strength of PB and MDF Abstract Dowels joints are one of the cost common adhesive-based furniture assembly joints. Dowelling is a simple, inexpensive, and reliable means of making butt and miter joints. Joint strength is largely determined by the holding power of the dowels. Use good quality dowels, diameter <= 0.5x the stock thickness. The longer the dowel, the greater the strength. Holes should be 0.005" oversized for edges, same as dowel on faces. Use 60%+ solids content PVA adhesive, applying glue to both dowel and hole wall, with slight squeeze-out. Adhesive-based Corner Joints for PB and MDF Abstract The thicker the panel, the stronger the joint. Simple butt joints' strength is limited by delamination; glue blocks or edge banding help. Dowel joints are standard, and work well; they should be glued only at the dowels, NOT between edge and face (!). Four dowels for 18" are standard. Biscuits have equivalent strength, but are easier to align at assembly. The strength of a well-made simple miter joint without reinforcement (dowels, etc.) is generally comparable to that of dowelled butt joints (!); dowels add little strength, but splines and biscuits do. Rabbets 1/3-1/2 the depth of the panel make strong joints, but tend to split. Dados are better, but less attractive. Rabbet and dado butt corner joints (= dado and tenon = dado box corner) combine a dado on one panel and a rabbet on the other. Dowelled butt joints are stronger (!). Dovetails are excellent, but require precise and time-consuming machining. Molded polyurethane joints (plastic splines) are as strong as or stronger than dowel joints. Metal Fasteners for PB and MDF Abstract Screws, nails, and staples are widely used. Screws are strongest. The type of screw affects strength by only +-10% (!), but PB screws are less likely to break. Screw diameter affects strength little, but screw length directly affects it. Screw diameter should not exceed 20% of stock thickness. High internal bond strength PB holds screws better. Edge screws have half the strength of face screws. Use full-length pilot holes; shorter holes do not increase strength. Ideal tightening is 3/4 turn past flush on the face; 3/8 past flush on the edge. Applying glue in the hole can increase strength as much as 45%. Staples are used for attaching fabric, etc., and to hold glued joints. Nails split panels, so should be >3" from a corner, and >6" apart. Ring shank nails hold better, plastic coated best. Drive them at an angle. Mechanically-based Corner joints for PB and MDF Abstract Most bolt and cam joints are 20-50% weaker than dowelled joints. Screw joints are comparable. Plastic corner block units can be much stronger in outward bending, but only comparably strong in inward. Even when they are equally strong, mechanically-based joints are often less rigid. These systems are most useful for ready-to-assemble manufactured kit furniture. Particle Shelf Systems (Builder's Bulletin #1) (not seen) All the above are free. They also sell: Particleboard from Start to Finish $12.50 Abstract (theirs, I haven't seen this) Ten chapters (120pp) of useful information for users of PB. Includes information on material handling and storage, sanding, machining and tooling, laminating, wet finishing, edge treatments, assembly and fastening, construction products, shelving and formaldehyde. MDF from Start to Finish $7.50 Similar abstract, 42 pp. ********************************************************************* 21). What are some of the common woodworking terms/abbreviations? HVLP - high volume/low pressure RAS - radial arm saw ROS - random orbital sander S2S - smooth 2 sides - surfaced 2 sides 22). How do I finish a cutting board? See the answer to question 13. 23). What is snipe and how do I eliminate it? End snipe occurs when the wood looses contact with the rear roller and allow it to rise slightly from the bed of the planer. Snipe can also happen on the beginning of the board as well. Snipe can be minimized or eliminated by providing support along the full length of the board on both the infeed and outfeed sides of the planer. Another way to minimize snipe is to do all of the planing before cutting pieces to length. This way the only snipe loss in confined to the end of 1 piece of wood. 24). How is lumber graded? The following was provided by David R. Mount (dmount@bigcat.missouri.edu) and added to the FAQ with his permission. ********************************************************************* The "Encyclopedia of Wood" from Sterling publishing is a good source of this information, a synopsis of which I'll provide here. As I recall (don't have it in front of me) Bruce Hoadley's book "Understanding Wood" has a comparable treatment. I'll give a brief summary of dimensions and grading as follows: Softwood Construction Lumber Most softwoods (though certainly not all) that are made into finished boards are intended to be construction lumber. This material is generally sold according to it's "nominal" dimension, typically 1 by something or 2 by something. Mininum thickness for planed, dry 1-by material is 3/4"; dry means average moisture content of 12%, maximum of 15%. Minimum thickness for 2 by material (planed and dry) is 1-1/2". For wet or "green" lumber (this includes formerly dry material that has been allowed to take up water and has not re-dried) minimum surfaced thickness is 25/32" and 1-9/16" for 1-by and 2-by material, respectively. For widths, the rules are the same for both 1-by and 2-by material. For widths up through 7 inches, the minimum dry, planed width is 1/2" less than the nominal dimension. So, dry 1x6 and 2x6 material should both be 5-1/2" wide. For widths of 8" and above, the width should be 3/4" less than the stated dimension (e.g., 1x10 should be 9-1/4" wide). Grading softwoods is complex (though not as bad as hardwoods) and it depends on the use (boards versus structural lumber), and the type and distribution of defects (tight knots, loose knots, spike knots, wane, shake, etc.). There are several different grading authorities, but the board grades most common in the U.S. are (in decreasing order of "quality") finish or select, #1 (common), #2 (common), #3 (common), and #4 (common). Structural lumber generally uses different terminology including such things as #1, #2, and #3 structural, superior, stud, utility, and several others. Ask your lumber dealer to explain the system by which their lumber is graded; there is a lot of variation from dealer to dealer. The "Encyclopedia of Wood" has pictures of the board grades; Hoadley's book may also, I don't recall. Hardwoods Standard thicknesses for hardwood lumber are as follows (in inches): Nominal (green) Dressed (dry and planed) Thickness Thickness ------------------------------------------------- 2/4 5/16 4/4 13/16 5/4 1-1/16 6/4 1-5/16 8/4 1-3/4 Notice that 2/4 lumber is officially listed as only 5/16" planed. In practice, hardwood stores I've been to generally sell material they call "2/4" that is actually surfaced to either 1/2" or 7/16". I don't know why. In my experience, the thicker sizes are typically sold as I've listed above. Hardwoods are generally sold as random widths, unlike construction lumber that has width controlled as tightly as thickness. In general, according to the Encyclopedia of Wood, dry hardwood is sold as the next highest inch down to 3/8" shy of the nominal dimension for less than 8 inches and 1/2" shy for greater than 8 inches. In other words, a 6" wide board may be as narrow as 5-5/8", a 10" board as narrow as 9-1/2". In practice, hardwood dealers vary in how they figure width into the board foot calculation; some go to the nearest inch, some to the nearest half inch, some to the exact dimension. Don't be shy to ask a dealer how he/she makes the calculation; you have a right to know. Grading hardwoods is *really* complex. Grades are determined by number, width, and length of clear (free of knots and other defects) cuttings that could be obtained from the board, which is in turn determined by the number and location of defects, primarily knots. The top three grades are "firsts", "seconds", and "select(s)". Hardwood dealers typically sell these grades together as "firsts and seconds" (known as FAS) or "select and better" (SAB). In short, if all the defects were cut out of these boards, they should yield between 83.3% and 100% of pieces with at least one clear face. The specific grading rules are much more complex, but this is the general idea. Note that there has been a movement to relax the requirements somewhat for black walnut. I also believe that many dealers sell wood as "FAS" that actually contains some select material; it's not a big deal usually, unless you need big wide long clear boards and are buying sight unseen. After these top three grades follows #1 common and #2 common. These grades allow a lower percentage of the board to yield clear cuttings (BTW, "cuttings" means smaller boards) and allows the cuttings to be narrower and shorter than in the better grades. #1 common should yield 66.6% to 100% clear cuttings (depending on the board size) while #2 common will yield 50% to 66.6%. A couple notes about #1 and #2 common boards. First, they are often not displayed right out front by a hardwood dealer; if you are interested in lower grades, ask about them. #1 and #2 boards can sometimes be a better buy; they are generally 20 to 70% cheaper than FAS boards so the cost per square inch of clear lumber may be lower if obtained from lower grade boards. Of course, this requires that you can use smaller pieces; you also have to figure in the cost of your time to cut around the knots. On the other hand, in more casual pieces I often leave some knots in the finished piece if they won't cause structural problems. Some of the most beautiful figure occurs near knots. Each person will weigh these variables differently. ********************************************************************* -- Jim Roche roche@cs.rochester.edu University of Rochester Computer Science Department Rochester, NY 14627