June 2010

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Last Meeting

The meeting was called to order by President Frank Ramsay at 7 PM. Guests introduced themselves as Doug Ryan, Dave Reese, and Lloyd LeDrew.

Frank announced that the Board has decided to disband the library, as there seems to be very little usage of the materials. The librarian, Mike Cooper, will be bringing one box of materials to each of the future meetings to sell to the membership until they are all gone.

Fred Reicher, the Membership Chair, passed out membership cards to those that had not yet received them.

Ed Marinaro was introduced as the Shows Chairman as a result of Board action earlier in the day. He will be forming a Shows Committee to investigate possibilities for a BAWA sponsored show of members' work.

Woodcraft has given us $70 worth of $10 gift cards as a result of rebates form BAWA member purchases. Frank offered them to the members at face value in order to convert them into cash for the Club treasury.

The Rebuilding Together event was very successful with some people staying until 8:30 PM in order to finish up all the tasks.

Jamie gave a short pitch about the 2x4 contest at the next meeting.

Stan reported that the raffle is about half way to the needed $100 in order to select a winner for the zebrawood.

Per Madsen introduced Yeung Chan as the scheduled speaker. Yeung took pains to correct an error in the resume provided in the last newsletter. He has never taught at the North Bennett School, but has delivered guest lectures there. Yeung talked about a project he has designed to build a replica of a Ming dynasty stool using the same mortise and tenon joinery as in the original, but using machines to make the joints rather than cutting them all with hand tools as would have been done 500 years ago. Yeung joked that the Chinese craftsmen would have loved to use the machines but did not have them then. He then went through each step of the construction process including the construction of the special jigs and fixtures that he developed. The chair will be the subject of a class he will be giving at the College of the Redwoods.

The seat of the chair is a frame and panel construction made of solid wood and the legs are round and installed onto the seat via mortise and tenon joinery. Special attention needs to be paid to be sure that the tenons in the seat frame do not impinge on the tenons for the legs. The seat is 1 ½ inches thick and the frame is made up of 4 pieces mitered at 45 degrees and held together with blind mortises and tenons. Yeung uses a horizontal mortising machine for all the mortises and emphasized the precision and ease of making the joint this way as opposed to a router where you would need to do hand chiseling to square off the mortise or round the tenon afterwards. He also emphasized the need to use a mechanical pencil with either 0.3 or 0.5 mm lead in order to have consistently thin and narrow marking lines. As a rule of thumb, he suggests that the tenon width be less than half of the frame width, closer to 1/3 of the width. He uses the table saw to cut the tongue and groove to join the pieces for the seat panels. He uses the router to cut the sliding dovetail for the seat support using a veneer shim at one end to the router fence so that the tail is tapered so that when the pin slides into place the joint tightens up. The legs begin as rectilinear stock and are formed into a cylindrical shape using a special cradle jig for the table saw. First the tenons in the end of the leg are made while the piece is still rectangular. Since the legs are splayed out at a 1.5-degree angle the tenons need to be perpendicular to this direction which is first cut on the end of the leg using the table saw. Yeung designed a very clever router jig that uses a straight bit to cut the tenons perpendicular to each other, with a shorter one under the place where the seat tenon is present. One needs to be careful to mark each leg to be sure to get the tenons correct. The slots for the aprons are then cut into each leg using a straight bit in the router. Next, the mortises are cut for the round stretchers between the legs. The piece of leg stock is then set into the table saw cradle jig and the 4 corners are cut off to form the crossection of a regular octagon. The cradle makes this job safe and quick. The edges of the octagon are then rounded off using a roundover bit in a table-mounted router followed by hand sanding to make a cylinder.

Stretchers: These are round rails joined to the round legs via mortise and tenons. The tenons must join to the round leg at a 1.5-degree angle. This can be assured by first making a template for the stretcher using 1/4" plywood to mock up the width of the tenon (3/8") and the curve of the leg. Use a 1-½ degree wedge to cut the tenon in the bandsaw using a fine tooth blade.

Aprons: Bandsaw the apron's shape oversize and trim to exact size using a template and a bearing guided router bit on a router table.

Yeung said that the stool has not been glued and in typical Yeung workmanship one can sit on it without the pieces being glued. The joints are that tight.

It was clear from the amazement of all present that this will be a considerable challenge for Yeung's students to complete in the time allotted. Yeung boasted that he was lucky and did not make any mistakes in doing this project though I am sure his students will not be so fortunate. On the other hand, Yeung is also a master at fixing mistakes so maybe they will be OK after all.

Yeung also said he will be teaching his 2-week summer class on Toolmaking and Machine Joining for furniture making at College of the Redwoods from June 21-July 2. The main project will be the construction of the Ming Dynasty replica stool described at the May meeting. BAWA members are cordially invited to drop in during class hours, 8:30AM to 5:30 PM, weekdays, to talk to students and observe their activities in the shop. A link to the class website is at www.crfinefurniture.com/1pages/sitelinks/sumclschan.html The College of the Redwoods is a 4-1/2 hour drive from SF at 440 Alger Street, Fort Bragg, CA 95437, (707)964-7056.

Show and Tell: Stan brought in some African artifacts. One was a tiger carving made from mkoma wood. It is supposed to be an African palm and Stan surmises that it is a Swahili word but none at the meeting recognized it. He also showed a carved wooden walking stick, which had been given to him as a gift as well as a beautiful carved picture, which had broken in shipping. Lloyd LeDrew presented a good tip for cutting tight fitting bridle joints by using the saw kerf cut into the cross piece as part of a spacer for the template to cut the bridle groove. Another member showed an app for the iPhone, which is a board-foot calculator and offered to let members act as beta testers for it.

Tech Talk: Yeung took the stage again to provide advice on how to fix mistakes that occur during a project to avoid having to make the part over again from scratch. The first problem was having a corner tear out. Yeung suggests planing the torn corner flat and cutting a piece from the project offcuts with similar grain and figure. The piece should be oversize and after it is glued in place it should be planed and sanded flat. The second problem was a case where a router might tear a chunk out of the piece. Yeung suggests using a sharp knife to smooth out the gouged surface and then cut a matching piece from an offcut. Again the exterior dimensions should be slightly oversize. The piece is again glued and clamped in place and then planed flat. He then talked about fixing loose mortises using a tapered block of the same wood. A hole drilled in the wrong place can be fixed by using a tapered plug cutter to cut a plug from an offcut with similar grain. This can be done even more cleverly by using a plug with a knot in it so the hole looks like a real wood defect! If you make a mistake on a mortise and tenon joint you can always replace it with a loose tenon. The joint will be just as strong as the original would have been. To avoid messing up in the first place you should always test your setups with scrap before working on the real piece. When using the router and shaper always work slowly with multiple shallow cuts. On the penultimate cut leave only about 1/32" for the final clean up cut and it will be smooth with little tearout. If a dovetail is too loose this can be fixed by tapping in a thin wedge. To avoid tearout on wood with difficult figure use a scraper plane with a long body to smooth it.


To end the meeting Stan drew three tickets for the door prizes. After the meeting adjourned, many members remained behind to talk with Yeung about the details of his excellent presentations.



Steve Rosenblum