Article: Rudolph "Rudy" Lopez Demonstrates For CMW February 21, 2015
February 26, 2015 08:00, submitted by Tina Collison (author: Bob Gunther, photos by Brian Johnson)
Rudolph "Rudy" Lopez Demonstrates for CMW February 21, 2015
Rudy began his relationship with wood over 37 years ago. With an education in drafting and design, the transition into woodturning has been a seamless flow into another creative endeavor. Learn more about Rudy Lopez on his website.
His ability to explain woodturning techniques in a simple, understandable manner has allowed him to share his skills and enthusiasm for woodturning. He has taught at the John C. Campbell Folk School and Arrowmont School of Arts and Crafts. He demonstrated at the 2013 NC Woodturning Symposium and he was very instrumental in the organization and production of the AAW Symposium in 2013 in Tampa, Florida. Rudy was also designated at an Emerging Artist at the 2012 AAW Symposium in San Jose, CA.
Rudy began his demo with a slide show showing examples of his work. He stressed that two factors are essential for good results in any turned project: sharp tools and good bevel control. Some of the pieces shown were winged vessels out of straight logs or limbs and vessels made of crotch wood. His square-to-round pieces were also shown. Both the Winged Crotch Bowl and the Square-to-Round Vase will be the topics of today’s demo. Rudy has provided handouts for each project.
The Winged Crotch Bowl was Rudy’s first project of the session; he used a piece of oak crotch with spalting. A drill had been used to remove the bark and cambium layers for insertion of the drive center. Cutting crotch blanks can be done two ways: either with the band saw or the chain saw. Both methods have their inherent dangers and need to be treated with caution.
The bottom of the crotch blank was placed at the tailstock and the bark side at the headstock. Rudy used a 4-prong, 1 ½ inch diameter spur drive. He placed the spur drive into the wood so that all 4 of the prongs were at a 45 degree angle to the grain. This provided a greater holding ability of the drive. By having the piece between centers one can adjust the position of the piece to better balance it and achieve possible design features. Once between centers the tailstock and the headstock, if it is moveable, are checked to be sure they are tight.
First the bottom of the piece (tailstock side) was trued up using a side grind bowl gouge with a 60 degree bevel and a secondary bevel. Rudy keeps five of the gouges, all the same, available so that he can go from one to another without sharpening. His other gouge has a 40 degree bevel. To true the bottom he used a pull cut and not a bevel rubbing cut. Lathe speed was started out slow for safety reasons. Then it was increased. A face shield was used. Only small cuts are taken with the tip portion of the tool when smoothing or truing up. A tenon was formed on the bottom surface so that the piece could be chuck mounted. Rudy prefers a dovetail tenon. The bottom was further shaped out using the pull cut toward the wing tips. The tenon was trued up with a parting tool. The portion next to the tenon was made flat (at right angle to the tenon) so that the jaws would sit flat on the piece and give a more secure tenon fit in the jaws. A push cut was then used to further thin the wings from outward toward the bowl area in the center. This gives a better finish than does the pull cut. The finished piece will sit on the six wing tips of the three wings.
Rudy used a negative rake scraper to further refine the surface of the bottom of the piece. It was not used for wood removal but for cleaning up of the surface. The cutting edge of the scraper was slightly rounded so that the bottom and top tips did not make contact with the wood. The negative rake angle makes getting a catch unlikely. This completed the bottom surface of the bowl. It was removed from between centers and placed in the jaws of a talon chuck and the tailstock was brought up.
Rudy then began shaping the top of the piece using a pull cut. By using a light over the lathe and looking at the piece from various angles one can see the bowl image and the wing thickness. He slowly thinned the wing areas out to the tips. To shape or thin the wings one wants the lathe speed to be as fast as possible but still safe. Push cuts were used to further thin the wings and produce a better surface finish. The wings need to be done in steps from outward to inward. This maintains the support of the more central wood mass. Rudy then changed to a 40 degree bevel bowl gouge to cut the transition area where the wings enter the side of the bowl section. A push cut was used to achieve final wing thickness. The remainder of the upper bowl portion was turned and the diameter of the bowl determined. The shape of the upper portion of the bowl needs to flow in a pleasing curve through the wings and into the lower bowl portion. This left only the bowl to be hollowed and completed the morning session.
Rudy continued with the Winged Crotch Bowl he began in the morning session. The central bowl area was hollowed in steps so that the wood would not warp too quickly. He used his swept back bowl gouge to hollow from outward to the center of the bowl. The edge or rim of the bowl was left the same thickness as the wing edges. It is important to have consistent wall thickness to help prevent cracking. Bowl wall thickness was done in stages from the top or rim inward to keep support in the bottom areas. Rudy used a laser set up to measure bottom thickness.
The piece was then removed from the jaws and placed on a jam chuck made of rubber called the “No nose Reverse Chucky” (from Rubber Chucky – enter Rudy10 to get a 10 percent discount) and the tailstock was brought up. The tenon on the base of the piece was turned away. Because of warping the cuts were not to a uniform depth. The negative rake scraper was used to further clean up the bottom and to make the center nub as small as possible.
The piece was removed from the jam chuck. A Japanese saw was used to cut off the nub. The interior of the bowl was sanded by a sanding mandrel held in the headstock on a Morse taper and the piece handheld. This completed the natural edge crotch winged bowl.
Next Rudy began the second of his two demo projects – the Square-to-Round Vase. The handout for this project is also available on his website at http://www.rudolphlopez.com. Basically a square column of wood is cut so that it has four sides. It is wider at the top than the bottom. It is placed between centers. The base part of the vase is at the tailstock and the top at the prong drive center.
First the base was trued up and flattened. Care was taken not to clip off the corners. Then a cove was turned as a practice cut for when the vase portion of the piece was turned. The base portion was then rounded removing the above turned cove and a tenon made. It is important that the tenon be parallel to the lathe and the surface for the chuck to rest against is flat.
The piece was placed in the jaws and the tailstock brought up. The top was flattened and the four corners made sharp and crisp. The upper cove shaped was turned. This left four rounded areas and four flat areas (thus the square-to-round vase shape). The tailstock was removed and the vase hollowed. Before hollowing the vessel was drilled using a one inch diameter metal drill with a #2 Morse taper. The drill bit had been modified to form a rounded area at the bottom of the hole and not leave a nub or a deeper point hole. Hollowing was begun using a spindle gouge that had a doorknob shaped handle and not the usual long handle. This gives Rudy much better control when turning beads and coves. This widened the hole into the vase.
Then a negative rake scraper was used to clean up the rim area. He then hollowed a small amount demonstrating how a bowl gouge can very carefully be used rolled over on its side in a scraping fashion to hollow. Then he demonstrated the Rolly Munro Hollower and explained why he feels this tool is much easier, more efficient and safer to use for end grain hollowing. This tool is used only for end grain hollowing and is presented on center to the wood. When measuring wall thickness do so only on the flat sides of the vase. The negative rake scraper was then used to clean up the interior walls.
The remainder of the outside of the vase was then shaped using the gouge after which the base was turned and a negative rake scraper used to clean it up. Then the pedestal and bottom were completed. Some sanding was done. The vase was removed from the chuck and placed on a jam chuck called the Reverse Chucky made by Rubber Chucky. It is adjustable so that different depth vessels can be chucked.
The base was turned, undercut, parted off and sanded. To sand the four flat sides of the vase a platform was placed on the tool rest post. A sanding disc was placed in the headstock and the four sides sanded flat removing any of the band saw marks left when the vase was cut out. This completed the square-to-round vase. It also completed a fast-paced and informative demo.
Submitted by Bob Gunther, Photos by Brian Johnson