Article: Dale Larson Demonstrates For CMW August 15, 2015
September 06, 2015 08:36, submitted by Tina Collison (author: Bob Gunther, photos by Brian Johnson)
Dale Larson Demonstrates for CMW August 15, 2015
Dale Larson has been turning for over 35 years. He comes to us from Gresham, Oregon. He primarily turns bowls from local hardwoods such as Pacific Madrone and Big Leaf Maple. His work is both functional and beautiful and is admired by both collectors and woodworkers. His work can be found in private collections all over the world.
He often demonstrates his bowl and sphere turning at the American Association of Woodturners (AAW) Symposiums in the USA and the Ripon Symposium in England. He also teaches and publishes articles in several woodworking and woodturning journals including the “American Woodturner.” He has taught at the John C. Campbell Folk School three times.
Dale is a founding member of the Portland Area Cascade Woodturners and has been an active member of the AAW for over 25 years. He is currently on the Board of the AAW. He served as president of the AAW 2013 – 2014. He last demonstrated for CMW in March 2011.
Dale began his demo with a slide show. He showed a large, standing walnut tree that had multiple large crotch areas. The branches were removed and then the large crotch pieces cut. Finally the trunk portion was felled. A front-end loader was used to fill two trucks with the large sections. Crotch portions were cut and split. When forming the crotch sections the piths were marked and then the crotch split. It turned out that there were no cracks, bark inclusions or other defects in any of the pieces. Multiple blanks were cut and they were sealed with Seal Tite. This ended the slide show.
Next Dale went to the white board and showed how to cut up a tree into blanks and what grain patterns would show in the blank. For oak he uses only quarter-sawn areas of the log. He then showed how he cuts burls from a tree and the bowl orientation in the blanks. After burls, crotch pieces are the most valuable. Dale showed how to orient cuts to achieve the most useful and effective crotch pieces. The feather area of a crotch is placed in the bottom of a piece. When cutting the crotch piece use a rip cut and not an end-grain cut.
Dale then turned to bowl turning: Safe bowl speed: rpm x diameter = 6,000 – 9,000 – not higher. Turn as slow as possible. If it comes off the lathe it hurts less if it’s going slower.
A green poplar bowl blank (12”) was placed between centers. A lathe speed of about 600 rpm was used. The piece was roughed with a bowl gouge. The tool was supported by Dale’s hip. It was roughed from the tailstock toward the headstock. The headstock side was cut toward the tailstock to prevent chipping. The top edge of the piece was rounded to prevent cracking. The bottom of the piece was flattened to prepare for the tenon formation. The tenon was shaped for the stronghold chuck - #3 jaws were used. The general bowl shape was then formed with the piece still between centers. Don’t push the tool too fast through the wood. Let the tool do the cutting so that tear-out is minimized.
The piece was removed from between centers and placed on the stronghold chuck. It was then hollowed using a bowl gouge. It was roughed to about 1 1/8” wall thickness (an 11” bowl). Dale would then date the piece and note where the tree came from. The end grain would be waxed with a cheap paste wax and then stacked on stickers so that wet wood would not touch wet wood, which helps prevent molding. After a few days Dale looks for any evidence of cracking. If cracking is found it means that the wood is drying too fast. Cracks are superglued, then dry shavings are placed in the bowl and the bowl is put in a bag. The chips are changed periodically and dry chips replace wet ones. If any mold forms the wood is sprayed with Clorox.
Dale uses a lot of Madrone burl. He boils the blanks for about 2 hours prior to the above drying process. Somehow this boiling process stabilizes the wood so that cracking is minimized.
Kiln drying can also be used over a 3 – 4 week period using a converted old refrigerator. Other drying techniques include using the microwave or soaking the wood in alcohol. Vacuum kilns can also be used. This method dries the wood from the inside out.
At this point Dale placed a dry bowl blank (Madrone) on the lathe using a faceplate. He trued up the outside and the inside (600 – 700 rpm). The same cuts were used as when the wet blank was roughed out. Wall thickness was not an issue at this point – he only wanted to make the piece round. The foot of the bowl needs to be the right size for the individual piece – most are 30 –35% of the diameter. A double foot is used because of the faceplate and the required screws (1/2”). Dale then refined the outside surface of the piece. He used his fingers to feel the surface. One can often feel what one is unable to see. Dale then oiled the outside of the bowl with walnut oil. He trued up the edge because he wanted it to be true before completing the final shape of the outside. This ended the morning session.
Dale continued working on the rim of the bowl. It was angled into the bowl. If the rim is left flat it will look “dead.” Mineral oil was applied to the edge and the surface finished using a planer blade whose edge had been blunted to about 45 degrees. Dale then returned to the outer bowl surface. Two large straight edge scrapers were used with burrs on them to finish the surface. These scraper blades had been made from large planer blades. They were held at a 45-degree angle to the wood. The oil had softened the wood so that a very smooth cut could be made. The wood was again oiled and then a cabinet scraper was used to refine the surface (outer) – NEVER the inside. Dale removed all tear-out using the scraper and always pulling it toward him. The cabinet scraper was used with the lathe on. The piece was again oiled then sanded. Dale uses Klingspor paper. Do not continue to use a piece of sandpaper if it gets hot – switch to a new piece. The heat can cause surface checks, especially on hardwoods. Dale started with aluminum oxide paper – 100 – 220 grit. During the sanding process oil can be reapplied as needed. Dale then switched to silicon carbide paper – 320 grit. The lathe was reversed during the use of this last grit. At this point any beads or grooves would be made – not after the completion of the hollowing. The outside was now complete.
Next Dale began the final hollowing. The upper 1/3 of the interior was turned first. Do not go all the way to the bottom because the support of the wood in the lower areas of the bowl is needed. The tool rest was above center for the first 2/3 of the hollowing, then below center for the remainder. Wall thickness was about 1” in the bottom. A half round scraper was used for the interior finishing cut. A negative rake scraper was used for the final cut. This completed the upper 1/3 of the interior. Dale then turned to a blunter angled gouge for the deeper portions of the bowl. Dale power sanded the interior and finished up with hand sanding and mineral oil with the lathe in both forward and reverse. Beeswax was applied using a cloth. The piece was removed from the lathe and the faceplate removed from the foot. The bowl was placed on step jaws that were made from Jumbo Cole Jaws and 2” thick hardwood. The foot was turned and the bottom was made concave. It was oiled and further scraped. Sanding followed with more oil application. This completed the utility bowl.
Dale then turned to sphere turning:
Step #1 – He placed a piece of Big Leaf Maple burl between centers and a cylinder trued up. The tailstock end was cleaned up. The length and diameter need to be the same. The center of the cylinder was marked. The tailstock end was rounded and then the headstock end. A bowl gouge was used.
Step #2 – A small cup chuck was placed on the tailstock and another on the headstock. The second turned sphere was placed between the cup centers and centered at equal distances from the tool rest. It was then turned round.
Step #3 – The piece was turned 90 degrees and replaced between the cup centers. It was trued up and turned. The shadow areas were removed. At this step both previously drawn lines (center) were parallel to the ways. A second sphere was made.
A jam chuck of green wood was turned. It was hollowed so that less than ½ of the sphere fit into the chuck. The sphere should not touch the bottom of the chuck. A hole was drilled through the chuck to accommodate an extractor to push the sphere out of the chuck.
To complete his demo, Dale used the Vicmarc Oval Turning chuck. It was mounted on the Oneway Llathe. There is no center on an oval shape. A green piece of roughly oval shaped wood was placed on the Talon chuck which was placed on the Oval chuck. All turning was done at the 9 o’clock position. The interior was not hollowed due to time restraints but when it would be done it too has to be exactly at the 9 o’clock position. If not, then wall thickness will not be uniform.
This completed a fast moving and educational demo. A DVD is available for rental in the CMW library.
Submitted by Bob Gunther
For additional information, Dale also provided his articles about "Green Turning Bowls" and "Turning A Sphere." Links to these files are provided at the upper right side of the article.