Michael Mocho is a self-employed woodworker / turner from Albuquerque, New Mexico with over 28 years of experience. He teaches in the Fine Woodworking Program at the Santa Fe Community College, and recently completed the International Turning Exchange residency with the Woodturning Center in Philadelphia this summer. He has demonstrated at the AAW National Symposium and many local chapters, and also teaches at craft schools including Arrowmont and the John C. Campbell Folk School. His work is in many public and private collections as well as juried and invitational exhibitions.

Morning Session:

Michael's demonstration began with a slide show of his diverse technical background; which includes furniture, architectural millwork, contract prototype work, musical instrument construction & restoration, and a variety of decorative boxes and other containers. He enjoys turning small boxes of contrasting hardwoods and uses textural techniques to add visual interest.

Michael demonstrated the techniques he uses to create a small "spire box" made up of 12 turned parts fit together. He used a large roughing gouge and very high rpm to turn a 2" x 2" x 12" square of hard maple to a cylinder. He described the dynamics of the proper stance that is necessary for an effective cut and good surface quality. A 1/2" wide parting tool was used to create three 4" blanks- each with a short tenon on one end to fit the chuck jaws so that there was always a shoulder of wood bearing on the top of the jaws for greater support. The smaller size of this tenon also prevents the holding jaws from sticking out past the diameter of the chuck body where they could strike a hand.

A discussion of the factors that contribute effective use of the skew was presented. Support of the cutting edge comes from three sources: the tool rest, your grip on the tool, and the surface of the wood where the bevel is rubbing. The tool rest was raised about 1/4" above centerline for a shearing cut, and set just slightly below center for V-cuts and end-grain. He uses a particular grip in which the left index finger goes under the tool rest and the left thumb contacts the top of the tool rest to create a stop on the left side of the tool. The wrist and the left shoulder are kept low, and the remaining fingers wrap around the shank of the skew, which is used like a knife with a light cut and little pressure. This prevents burning the wood and gives a very smooth surface ready for detailing.

He then used a blunt-ground spindle gouge to form the hollow on the underside of the box, then chattered the center of the hollow using a 1/4" round-nosed scraper held below center and with the toolrest set away from the wood so as to encourage the vibration of the tool. Although small diameter pieces require higher RPM for smooth cuts, the lathe is slowed below 800 RPM in order to produce the chattered surface. Details were added by using the tip of a small skew held flat on the tool rest as a scraper. Taking a few seconds to hone a micro-bur on the edge with a single stroke of the diamond plate produced a very smooth surface on the maple. A round nosed scraper was then used to further refine the interior of the base using a shearing cut in which the tool was tilted on edge to about 45 degrees and pulled from the center towards the edge along the centerline.

Michael then demonstrated the use of a shop-made jig made to fit the toolrest base and hold a 1/4" punch parallel to the bed and on the lathe axis. This simple tool was used to emboss a pattern in the base of the piece at indexed intervals. The punch was struck against the wood to create a mark and returned with a small spring. The wood was rotated by hand to the next indexed stop and the process repeated to create a pattern. A variety of leather punches can be modified to fit the holder.

The piece was then reversed in the chuck, and the interior drilled out with a sharp carbide Forstner bit held in the tailstock chuck. First a small divot was created at center for the tip of the drill bit to start in, which helps prevent the bit from wandering off center. The RPM is lowered to around 600 and the hole is drilled slowly in stages to prevent the chips from choking the bit into the piece. A dab of beeswax on the bit for lubrication makes for a smoother hole, a cooler cut, and an easier withdrawal. The interior of the bored hole was then polished with sandpaper wrapped around a slotted dowel rod of the appropriate size. A small disc of the same wood was turned to fit the hole exactly and then dropped into the bottom to cover the mark made by the point of the Forstner bit. This basically completed the base or bottom of the box. Final box shape can be altered with the bandsaw, disc, or drum sander, and grain orientation is always an important design consideration.

The top of the box was then begun. A small plug was turned to a very slight taper to fit the sanded bore. The end-grain area was then textured with the rotating spiral tool. The first attempt was not acceptable and was repeated. The plug was refined with a few detail lines and parted off, reversed and held by friction in a scrap that had been bored with the same sized Forstner bit as the base. A 3/16" hole was drilled into the plug and spiral texture was added around it. This completed the plug to be placed into the top of the base.

>Michael then showed an assortment of similarly turned parts with 3/16" holes that can be joined together on a dowel pin to create the decorative top. An easy way to assure a perfect fit is to turn dowels or tenons a bit oversize, and gradually reduce the diameter by force them through a metal drill index plate while spinning at about 600 RPM. The plate is held over the empty throat of the tailstock quill, which keeps it exactly perpendicular to the lathe axis. The crisp edges of the hole in the metal plate push a shaving down the wood to create the exact desired diameter. The attached shaving must be removed from the root of the tenon in order to form a perfect shoulder. This completed a most interesting morning session.

Afternoon Session:

Note - Michael feels that when you have a piece with a magnificent grain pattern you should not embellish with a lot of details or texture, which can sometimes clutter the form.

Michael began the afternoon session demonstrating chatter work techniques on a piece of hard maple spinning below 1000 RPM. Chattering occurs when either the tool is deflected or the work piece is deflected. By adjusting the tool rest so it was set back from the wood, and using a skew placed flat on the tool rest, the edge was draw up from below center with a bit of pressure allowing it to bounce and vibrate on the end grain. The most effective line of motion is at a 7:30 radial clock position. Holding the tool at different angles produced different patterns. Faster lathe speeds create fewer chatter marks, and slower speeds create patterns with more detail. Commercial chatter tools have the bounce of the tool built in by using a flexible spring steel cutter, but nearly any tool can be used to create a chattered surface. It all depends on the angle of presentation, the density of the material being textured, RPM, and the pressure applied against the wood. The farther the tool extends off the rest, the slower it will vibrate or chatter. Chatter must be applied to a smooth end-grain surface and can crush and mangle fibers if over done.

Spiraling was then demonstrated using a commercial tool made by Sorby. The tool is basically a rotating gear-shaped scraper in which each tooth cuts a groove that another tooth engages in. The angle at which the tool is held determines how many lines are cut into the surface- flatter angles produce fewer lines, and greater angles create spiral patterns with more lines. The tool can be used on both side and end grain, though tool rest height is critical for the cutting edge to be working exactly at center. Slower RPM is essential since the ridges of the spirals can be quite fragile and the teeth of the cutting gear will skip if too much pressure is used. When the spinning gear is held vertically it can also be used to emboss the surface of the wood. The tool is sharpened by holding it to a rotating scrap and honing the top of the spinning gear with a diamond plate.

Next Michael discussed the modifications made to his 1750 rpm grinder. He added a series of small diameter leather-covered honing wheels spaced along a shaft positioned above motor and driven via a pulley and short belt. They are used with rouge to polish turning and carving tools, though caution must be used to avoid over-dubbing the edges which changes the geometry of the contact bevel and thereby the cutting dynamics. He recommends using 60 or 80 grit aluminum oxide wheels to avoid burning HSS tools. When using a diamond wheel dresser, be sure to support it on the tool rest rather than free-hand to prevent the wheels from getting out of round. The 8-inch wheels are discarded when they wear down to about 6 1/2 inches. He prefers a foot switch to turn the grinder on so both hands can be used to hold small tools steady at the proper angle.

Michael then showed a box of shapes that he referred to as his three-dimensional "sketches" - small turned forms that have been altered by cutting into the turned cross section to create flats, hollows or openings into the interior. Most of the shaping is done using a variety of abrasive tools including disc sanders, drums of different diameters, and a shop-made belt sander with different shaped contact platens. The platen is a piece of wood sawn to the desired profile and covered with graphite impregnated canvas which allows the 4" x 24" sanding belt to slide over it without much friction. The belt is driven by a 2" rubber covered drum on a 1/2 hp 1725 rpm motor. He uses the machine with a 120 grit belt to cut into the turned forms at different angles- then refines the forms using finer grit belts, which have much more surface area than a sanding drum and also dissipate heat better.

This completed a very detailed and informative demonstration. Michael touched on many points. Hopefully I have incorporated as many as possible into this article. For a full understanding and appreciation of this demonstration an edited tape and DVD will be available in October 2004.

Bob Gunther

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