Article: Stuart Mortimer Demonstration For CMW September 28, 2013
October 02, 2013 16:17, submitted by Tina Collison (author: Bob Gunther, photos by Tina Collison)
CMW Demonstrator Stuart Mortimer, September 28, 2013
Stuart Mortimer was born in Scotland and lives in Hampshire, England where he has his home and a large, well-equipped workshop. There he teaches, demonstrates, has workshops and hosts woodturning clubs.
In 1969 Stuart got his first lathe and from that point on he was hooked on turning. Like most turners he turned at school and built on that beginning, learning to cut properly along the way. He soon found he had a flair for turning and after retiring he entered and won several national competitions. He began to write for the “Practical Woodworking” magazine and from that point on he was on “the circuit.” He turned professional in 1992 and has enjoyed teaching and demonstrating throughout the U.K., Europe, Scandinavia, and the USA. In 1995 he wrote a definitive work on turning twists by hand entitled “Techniques of Spiral Work” published in England by Stobart Davies, Ltd. (ISBN 0-85442-063-0)
Stuart holds the Authenticated World Record for the largest bowl turned from one piece of wood. This was turned at the American Woodworker show in Philadelphia and Detroit in 1997. In that endeavor he was assisted by his friend Steve Blenk from Seattle. Stuart is on the Register of the Worshipful Company of Turners and is a member of the Association of Woodturners of Great Britain and the AAW.
Many of Stuart’s pieces are sculptured and demonstrate twists and open weave patterns of varying complexities. Some are extremely ornate. He uses many hardwoods and burls either by themselves or in combination. He last demonstrated for CMW on June 17, 2006 and also did a one-day hands-on class.
Stuart began his demo with an introduction to twist layout and formation. He used a 2x2x12” piece of poplar that was placed between centers using a chuck and a live center. He turned at a very high speed. The piece was shaped into a cylinder using the skew that had had the heel softened. The piece was left square for about 2 ½ inches at the headstock end. This provides a handle to hand turn the piece when cutting the twist and a flat surface to make notes pertaining to the type of twist formed on the piece. This is especially important when first doing twists so that one can keep track of what one is making and has made in the past. Twists can be confusing so it is a great reference for future twist work.
The tailstock was removed and a hole drilled about half way into the 2” cylinder. Stuart did not use a drill bit. First he formed a countersink using a skew. Then the hole was drilled with a spindle gouge. It was drilled in increments of about ½ inch so that wood could be continually cleaned out of the hole. The diameter of the hole was about ½ inch. The tailstock was brought back into place and the piece was trued up. Next, with the lathe running, vertical lines were inscribed on the piece. The first ones were made at about 2” increments (diameter of the piece). These were then halved and then halved again. This created ½” spaces the length of the piece. Every 4th line was highlighted beginning at the headstock end. Then four horizontal lines were drawn at 90 degree increments horizontally the length of the piece. The lines were numbered 1 to 4 at each end. A left hand (double) twist was laid out. Lines 1 and 3 were connected. Also, Lines 2 and 4 were connected with 4 spaces between each. A small saw was used to cut the pitch lines. Then an old, specially ground gouge that had previously belonged to Dennis White was used to hand cut along the pitch lines while the lathe was rotated by hand. This represented the older, traditional way to do the cuts.
Stuart then showed the use of the microplane to widen and refine the twist. A Foredom tool with a pointed rasp was used. This was even easier and quicker. To make the process even faster the Arbortech with the 4 inch triple carbide cutters was used. This tool is very effective but can be quite dangerous. Be certain that it does not have a plastic guard over the blade. The guard needs to be metal. There is a smaller, 2” version that may be somewhat safer to use and is considerably lighter in weight. Before using the Arbortech for twists, practice using it to make cuts on flat boards. One needs a handle that has the on/off switch exactly where the thumb rests so the machine can be used safely and efficiently. Arbortech is not the only brand – there are Bosch, Hitachi, and possibly others.
The Arbortech was used to open the twist and to deepen it. The corners of the double twist were removed with a palm plane. Stuart planes three times on each edge. The palm plane has a captive blade so that only the edge of the plane runs along the bottom of the twist. The corners can also be removed with the Arbortech, the microplane and the Foredom. Stuart then sanded the twist using a stick wrapped with sandpaper. The stick was shaped to roughly match the contour of the twist. Finally, Stuart sanded with the lathe running slowly. A ribbon of cloth backed sandpaper was used. This could be done with the lathe running forward and in reverse.
Stuart then used the small hand saw to cut lines in the base of the already formed twists. This opened the twists. This can also be done with the Arbortech. This formed the open double twist. The rough areas created when the twist was opened can be cleaned up using a skew as a chisel. Then Vitex sandpaper was used to sand the twist. The Vitex is a tough cloth back paper that comes in many grits and can be torn to the desired width ribbons.
Different twists can be made by increasing the number of horizontal lines on your initial layout: i.e.: 8 etc. This completed the twist layout and formation of the demonstration.
Twisted Stem Goblet:
Stuart placed a 3x3x12 inch piece of cherry between centers. It was rounded with the bowl gouge. A tenon was formed on the tailstock end and the piece placed in the jaws of the Stronghold chuck. The tailstock was brought up. The piece was trued up. About 3 inches were parted off from the tailstock end because the piece was longer than necessary. When parting the lathe speed is slowly reduced as the parting process is nearly completed. Stuart parts off using what is basically a half skew.
There are only three cuts in woodturning – straight, concave, and convex. All three of these cuts are utilized in turning the cherry goblet. First Stuart formed the top or cup of the goblet on the exterior. Then he opened the goblet. First he determined the wall thickness. A hole was drilled with the spindle gouge to the desired depth of the goblet. It was hollowed using the side of the gouge at the 9:15 and 11:00 o’clock positions. To make final cuts in the interior of the goblet pressure was applied to the outside wall using a folded paper towel. Stuart’s hollowing gouges have a shallow flute and a rounded bevel. There are no wings and no hollow grind so that catches are eliminated. There are 3 of these tools in the set. They are called Stuart Mortimer Hollowing Tools and are available from Hamlet and Craft Supplies, USA. The goblet was sanded from the bottom up using multiple grits. Abranet was used to produce the final surface. It was then sprayed with lacquer and quickly buffed with wax. This completed the top of the goblet.
Stuart then turned to the twisted stem. He used a special rounded tailstock head on the One-Way live center to support the piece. It is padded with paper towel. The base of the goblet was shaped and sanded. The base of the goblet was shaped leaving enough wood at the base to permit it to be parted off when completed. A bead was formed at the top of the stem at the base of the cup portion and another at the bottom. The area of the stem was then reduced in diameter.
Stuart partially parted off the base so that that area was made weaker than the stem. This was done so that if a break did occur it would be at the base and the goblet would still be intact. A spindle gouge was used to from fillets on the top and bottom beads. The stem portion was further shaped with a slight taper – narrower at the top. A small cove was formed at each end of the stem. The base was further weakened and made concave. The twist was done forming a triple twist. This was done simply by eye-balling and using a small handled Italian rasp (Corradishop.com). There were a coarse and a fine version. The twist was cut and then the second and third twists were done. A chain saw file was used to soften the edges. Vitex paper was used to sand the twist grooves. The twist was polished with a cloth ribbon. The goblet was completely parted off. This completed the triple ribbon twist goblet and the morning session.
Open Hollow Form:
Stuart began the session with a 6x6x12” piece of green sycamore between centers. A spigot was formed on the tailstock end using a bowl gouge and the piece was placed in the jaws. It was rounded into a cylinder. Stuart showed how to form a half sphere at the tailstock end by repeatedly turning off the corners until the sphere shape evolved. He formed the piece into an egg shape utilizing a little over half the length of the cylinder. He used a pull cut to define the shape.
He then marked the piece with vertical lines at ½ inch intervals. The top two spaces were not used in the laying out process. Four spaces were marked off, then 5 and then the remainder to the bottom. He then drew 4 indexing lines at 90 degrees. He divided the 4 into 12 then drew the pitch lines. At the bottom he drew the pitch lines halfway between the horizontal lines. At the top the pitch lines were nearly parallel to the lathe bed.
Stuart then used the Arbortech to start the bine cuts at the top of the vessel and then the full cuts toward the base. (NOTE:The bine is the hollow form wood remaining and the interbine is the space that is left after the wood is cut away with the Arbortech. In other words, the bines and interbines alternate around the hollow form - wood, space, wood, space, etc.) He extended the cuts into the base area. The interbine spaces were cut 3/8 inch deep. Every third one was then cut as deep as the cutter would go. The tailstock was removed and the hollowing begun using his hollowing tools. However, before hollowing a light cut was made on the exterior to balance the piece. As the hollowing progressed the shavings began to come out between the bines where the spaces were cut deeper. He then used a light placed inside the piece to show wall thickness. He continued the push/pull cut when hollowing, always cutting with the left side of the gouge.
The tailstock was brought up and the egg shaped was further defined at the base. A bead was formed at the top and the base. A black line was drawn at the upper and lower ends of the binds. The Arbortech then opened the spaces between the bines and made them all the same thickness. A palm plane was used to round the edges of each bine. Vitex sandpaper was used to sand the inside of the bines. A spigot was formed on the base so that a decorative base could be made at a later date and fitted to the piece. It was parted off. Once parted several holes were drilled into the bottom of the spigot. Tape was paced around the spigot and CA glue placed in the holes. Tape was folded over the holes. This stabilized the spigot and prevented cracking as the piece dried out. This completed the open hollow form vessel.
Closed Thin-walled Hollow Form:
A second piece of 6x6x12” green sycamore was placed between centers and a spigot turned on the tailstock end. It was placed in the chuck and roughed into a cylinder. The 4” diameter of the remaining piece was reduced to about 4” and turned into an egg shape. A depth hole was drilled and the piece hollowed. The deeper areas were hollowed first. When hollowing was completed the shavings were evacuated. A light was placed inside the piece to check wall thickness. The inside was sprayed with lacquer which helped force the water to the exterior of the piece. This permitted sanding.
The light was then placed in the tailstock and inserted into the vessel so that it could be lighted while turning. The outside wall was further turned and more and more light penetrated through the wall as the thickness decreased. Once the final wall thickness was achieved the piece was sanded. A spigot was formed at the base and then parted off. Holes were drilled in the spigot as done earlier and CA glue applied. It was wrapped with tape. This completed the thin-walled hollow form.
The final portion of Stuart’s demo consisted of turning a pigtail twist. A 2x2x12”dry poplar piece was placed between centers using a chuck. It was roughed into a taper with the narrow end at the tailstock. The Arbortech was used to create the twist. A rasp was used to further define the shape. The lathe was turned on and a tear drop shape formed over the twist. This produced the pigtail form.
This completed a very interesting and fast paced demo. A DVD will be available in the club library in November 2013.
Submitted by Bob Gunther