Last meeting
Guests this month included: Sam Crews, who makes furniture; Rich Eposto, a retired carpenter; and Chongor Pinte, who's a beginning woodworker. Welcome to all!
Announcements: Jay Perrine, Program Chair, discussed upcoming meetings. Don't forget to bring your Jigs and Fixtures for the October Meeting. President Linda Salter asked for volunteers to man the booth at the Woodworking Show on November 2nd to the 4th. Arnie Champagne announced the show of the School of the Redwoods graduates' work at the Highlight Gallery in Mendecino, Sept 7 - 9. James Krenov will be speaking. Work will be shown from former students from around the country. The display will be for one month, but reserve a room early if you want to hear Krenov or attend the opening. Jim Voos announced woodworking classes starting at Laney College in Oakland next Thursday, August 23. Jay van Arsdale has a couple classes and there are Saturday and evening classes. Jeff Preston mentioned that he just completed a great welding class at the College of San Mateo. This skill can be of help for furniture making in mixed media. Outreach Chair Bill Henzel reminded everyone of the Toy Making Workshop this Saturday, August 18, at Per Madsen's shop. He handed out directions.
SHOW & TELL
Bob Hulgan displayed a long-term project: a reproduction of a very petite 19th century Morris rocking chair. It has taken him three years to make. He photographed and measured the original. He purposely made it slightly small to fit his wife. He made his own brass hinges and added the brass rod and hook at the back. He fumed the oak and turned the spindles for the sides. Bob discussed the problems he had to solve to complete the project. Once the upholstery is finished it will be a very nice little chair.
Arnold Champagne passed around parts of some letterboxes he's making. They are to hold writing instruments, paper and the like. One uses maple with a mahogany frame; another has a curved top design. He laminated this curved shape using a pressed board mold shaped by a router. It will have marquetry in the center. Very elegant boxes.
One of Sig Rich's favorite woods is Mesquite. Since he participated in an Elder-Hostel experience in Kingsville, Texas recently, he went to the U of T campus library there and looked up Mesquite wood. He passed around a copy of a booklet he found on cutting, drying and fabricating Mesquite wood into flooring, etc. Published in 1983 it is filled with useful information about the characteristics of this wood. It is out of print, but our speaker this evening said that a copy is also available at the Wood library at the Forest Products Lab at Richmond where he works.
On a similar note, Doug Ryan pointed out that the July 2001 issue of Wood and Wood Products magazine has an article on "pre-compression wood". He passed around a copy of the article and some of his experimental ram hardware he made. He also passed around some wood pieces he tried compressing with mixed results. It was very interesting.
Paul Reif displayed a poster made of photos from Yeung Chan's Woodworking Techniques class he took at the College of the Redwoods. He also showed some wood boxes he's making of a very simple design. The bottoms utilize some of the Finn ply material that Per Madsen gave us when we visited his shop. They are set into a groove in the side. The sides are made of Port Orford Cedar or Lacewood, and the tops slide in a groove routed into the sides. The ends of the sides are mitered. He places a small hole in the top to form a finger pull for opening these simple, elegant boxes.
Linda Salter described her latest segmented bowl she had made. She couldn't bring it because it just sold – congratulations!
MAIN PRESENTATION
John R. Shelly, Ph.D. is a Cooperative Extension Advisor in Forest Products and Biomass Utilization at U.C. Berkeley's Richmond Field Station, otherwise known as the "Forest Products Lab." He gave a great material science talk on wood. We went back to school – and this is a good thing!
Dr. Shelly looks at wood from the perspective of a wood science technologist, who studies how wood performs. His lecture covered many, many details of the anatomical structure of wood and its physical properties. How trees grow, and how wood behaves when we cut, dry and use it. It would be very difficult to write all of the topics that he discussed, as there were lots of graphs, charts and drawings. One really needed to be there. For example, he discussed at length how water flows through the tree, the difference between radial and tangential shrinkage, and how to predict the amount of each.
Did you know that there are four groups of chemicals in wood? Cellulose (sugar) makes up about 40-50%. Hemicellulose, that is long chains other than sugar, composes 25 – 30%. Lignin, a "glue molecule" that helps bond cells and gives wood its strength, accounts for 15 – 20%. And finally Extractives, a variety of materials that can be "extracted out" with water or alcohol, make up less than 5% but give decay resistance and specific color to the wood. John explained the role of each of these chemicals in the life of the tree, and what effects they can have on the lumber we're using to build projects with.
He diagrammed the internal cell structure of typical hard and softwoods, showing how water passes through the cells in the living tree and then when we try to dry it. He discussed the various types of cells within the tree and what their functions are. For example, the "ray cells", those flattened bands of tissue extended horizontally in a radial plane in the tree, store sugar (the food). So if they are filled they don't conduct water much. On the subject of drying: "Freshly cut softwoods have high moisture in the sapwood. Measured on a weight basis of volume it can be up to 150%, versus the heartwood which is usually only has about 40% (moisture content)." When drying wood, the outer, sapwood will give up its moisture relatively quickly, but then things may go awry. For example the "pits" may close off as drying takes place, which will make it difficult for the water to get out of the heartwood.
So John reminded us that when drying wood, always sticker it evenly in straight lines, in order to transfer the weight all the way to the bottom and not overload individual pieces of drying wood as they will bend. Sticker the top of the top layer too, then add weight to the top board to keep the wood near the top of the pile from cupping or twisting up. The wood is relaxing as it dries. The cells slip when under a load over time. As you can imagine each board dries from the surface first, so the "shell" or outer portion of the board shrinks. This shell can become like a rubber band tightening around the outside leading to stresses and drying defects. So dry your wood SLOWLY.
This led to a discussion of "case-hardening" and other defects found in dried lumber. Did you know that in wood dried to a moisture content of 10%, when measured at the shell only, the interior moisture level may still be as high as 30%? The difference between the amount of moisture in the shell and the inside can be as high as 20%! This will obviously cause stress problems that will appear as you try to machine the wood. One solution is to cut your wood oversize, then set it aside and wait for it to dry to the "equalization moisture content" of your particular locality. The national average for drying furniture lumber is usually 6% moisture content, but such measurements are taken only at the surface or shell area. Moisture equalization in the Bay Area occurs at 10 to 12%. So kiln drying wood to a point lower than this sets the stage for internal stresses to occur.
For further reading he suggested R. Bruce Hoadley's books "Understanding Wood – A Craftsman's Guide to Wood Technology" and "Identifying Wood – Accurate Results with Simple Tools". Taunton Press has recently published updated editions of one or both. He also recommended the recently published "Woods of the World" by the International Wood Collection Society.
We thank Dr. Shelly for his very informative presentation. We will all be much more careful about choosing wood for our next project armed with this knowledge of how wood behaves.
By Craig Mineweaser - Secretary
TOY WORKSHOP
The Toy work shop was held at Per Madsen's shop called Rackit in San Francisco on August 18th. Here is Bill Henzel's report.
The participants were Arnold Champagne, Bill Henzel, Paul Reid, Greg Rice and Jim Voos. We made large tinker toys. These toys consisted of wooden blocks of varied shapes which connect to other blocks with different length dowels. We sanded all of our wood before cutting on Per's large panel sander. This eliminated the need for sanding after cutting and drilling. Paul and I cut cubes, triangles and other geometrical shapes on the table saw and chop saw. Jim became an expert on rounding all edges on a small table saw setup for this purpose. After all the edges were rounded, Greg drilled numerous 0.5 inch diameter holes and finally somewhere in the far recess of the shop, Arnold rounded over the ends of countless dowels on a large Grizzly belt sander. Per keep all his tools running smoothly for us and assisted us with his special jigs.
We took our traditional restaurant lunch break at a Thai barbecue place. Good food, friends and woodworking made for perfect day. We want to thank Per for his outstanding hospitality and the use of his wonderful shop. We are looking forward to donating these toys to needy children at Christmas.